Auto merge of #104417 - mejrs:mir_build, r=davidtwco

Migrate rustc_mir_build diagnostics

Rebases https://github.com/rust-lang/rust/pull/100854

~~The remaining issue is how to better resolve https://github.com/rust-lang/rust/commit/72bea68af4ee2a41c44998916f6a789163f12e7d~~

~~The diagnostic macros seems to generate a broken diagnostic, and I couldn't figure out how to manually format the fluent message, so I hardcoded the format string for now. I'd like pointers to a better fix for this.~~

Also, I'm not 100% sure I didn't mess up a rebase somewhere 🙂

r? `@davidtwco`

12 files changed, 1203 insertions, 302 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 4cf3f3ddedb..cce203ef728 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4069,6 +4069,7 @@ dependencies = [
  "rustc_hir",
  "rustc_index",
  "rustc_infer",
+ "rustc_macros",
  "rustc_middle",
  "rustc_serialize",
  "rustc_session",
diff --git a/compiler/rustc_error_messages/locales/en-US/mir_build.ftl b/compiler/rustc_error_messages/locales/en-US/mir_build.ftl
new file mode 100644
index 00000000000..60d3d3e69ab
--- /dev/null
+++ b/compiler/rustc_error_messages/locales/en-US/mir_build.ftl
@@ -0,0 +1,301 @@
+mir_build_unconditional_recursion = function cannot return without recursing
+    .label = cannot return without recursing
+    .help = a `loop` may express intention better if this is on purpose
+
+mir_build_unconditional_recursion_call_site_label = recursive call site
+
+mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe =
+    call to unsafe function `{$function}` is unsafe and requires unsafe block (error E0133)
+    .note = consult the function's documentation for information on how to avoid undefined behavior
+    .label = call to unsafe function
+
+mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe_nameless =
+    call to unsafe function is unsafe and requires unsafe block (error E0133)
+    .note = consult the function's documentation for information on how to avoid undefined behavior
+    .label = call to unsafe function
+
+mir_build_unsafe_op_in_unsafe_fn_inline_assembly_requires_unsafe =
+    use of inline assembly is unsafe and requires unsafe block (error E0133)
+    .note = inline assembly is entirely unchecked and can cause undefined behavior
+    .label = use of inline assembly
+
+mir_build_unsafe_op_in_unsafe_fn_initializing_type_with_requires_unsafe =
+    initializing type with `rustc_layout_scalar_valid_range` attr is unsafe and requires unsafe
+    block (error E0133)
+    .note = initializing a layout restricted type's field with a value outside the valid range is undefined behavior
+    .label = initializing type with `rustc_layout_scalar_valid_range` attr
+
+mir_build_unsafe_op_in_unsafe_fn_mutable_static_requires_unsafe =
+    use of mutable static is unsafe and requires unsafe block (error E0133)
+    .note = mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+    .label = use of mutable static
+
+mir_build_unsafe_op_in_unsafe_fn_extern_static_requires_unsafe =
+    use of extern static is unsafe and requires unsafe block (error E0133)
+    .note = extern statics are not controlled by the Rust type system: invalid data, aliasing violations or data races will cause undefined behavior
+    .label = use of extern static
+
+mir_build_unsafe_op_in_unsafe_fn_deref_raw_pointer_requires_unsafe =
+    dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+    .note = raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
+    .label = dereference of raw pointer
+
+mir_build_unsafe_op_in_unsafe_fn_union_field_requires_unsafe =
+    access to union field is unsafe and requires unsafe block (error E0133)
+    .note = the field may not be properly initialized: using uninitialized data will cause undefined behavior
+    .label = access to union field
+
+mir_build_unsafe_op_in_unsafe_fn_mutation_of_layout_constrained_field_requires_unsafe =
+    mutation of layout constrained field is unsafe and requires unsafe block (error E0133)
+    .note = mutating layout constrained fields cannot statically be checked for valid values
+    .label = mutation of layout constrained field
+
+mir_build_unsafe_op_in_unsafe_fn_borrow_of_layout_constrained_field_requires_unsafe =
+    borrow of layout constrained field with interior mutability is unsafe and requires unsafe block (error E0133)
+    .note = references to fields of layout constrained fields lose the constraints. Coupled with interior mutability, the field can be changed to invalid values
+    .label = borrow of layout constrained field with interior mutability
+
+mir_build_unsafe_op_in_unsafe_fn_call_to_fn_with_requires_unsafe =
+    call to function `{$function}` with `#[target_feature]` is unsafe and requires unsafe block (error E0133)
+    .note = can only be called if the required target features are available
+    .label = call to function with `#[target_feature]`
+
+mir_build_call_to_unsafe_fn_requires_unsafe =
+    call to unsafe function `{$function}` is unsafe and requires unsafe block
+    .note = consult the function's documentation for information on how to avoid undefined behavior
+    .label = call to unsafe function
+
+mir_build_call_to_unsafe_fn_requires_unsafe_nameless =
+    call to unsafe function is unsafe and requires unsafe block
+    .note = consult the function's documentation for information on how to avoid undefined behavior
+    .label = call to unsafe function
+
+mir_build_call_to_unsafe_fn_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    call to unsafe function `{$function}` is unsafe and requires unsafe function or block
+    .note = consult the function's documentation for information on how to avoid undefined behavior
+    .label = call to unsafe function
+
+mir_build_call_to_unsafe_fn_requires_unsafe_nameless_unsafe_op_in_unsafe_fn_allowed =
+    call to unsafe function is unsafe and requires unsafe function or block
+    .note = consult the function's documentation for information on how to avoid undefined behavior
+    .label = call to unsafe function
+
+mir_build_inline_assembly_requires_unsafe =
+    use of inline assembly is unsafe and requires unsafe block
+    .note = inline assembly is entirely unchecked and can cause undefined behavior
+    .label = use of inline assembly
+
+mir_build_inline_assembly_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    use of inline assembly is unsafe and requires unsafe function or block
+    .note = inline assembly is entirely unchecked and can cause undefined behavior
+    .label = use of inline assembly
+
+mir_build_initializing_type_with_requires_unsafe =
+    initializing type with `rustc_layout_scalar_valid_range` attr is unsafe and requires unsafe block
+    .note = initializing a layout restricted type's field with a value outside the valid range is undefined behavior
+    .label = initializing type with `rustc_layout_scalar_valid_range` attr
+
+mir_build_initializing_type_with_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    initializing type with `rustc_layout_scalar_valid_range` attr is unsafe and requires unsafe function or block
+    .note = initializing a layout restricted type's field with a value outside the valid range is undefined behavior
+    .label = initializing type with `rustc_layout_scalar_valid_range` attr
+
+mir_build_mutable_static_requires_unsafe =
+    use of mutable static is unsafe and requires unsafe block
+    .note = mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+    .label = use of mutable static
+
+mir_build_mutable_static_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    use of mutable static is unsafe and requires unsafe function or block
+    .note = mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+    .label = use of mutable static
+
+mir_build_extern_static_requires_unsafe =
+    use of extern static is unsafe and requires unsafe block
+    .note = extern statics are not controlled by the Rust type system: invalid data, aliasing violations or data races will cause undefined behavior
+    .label = use of extern static
+
+mir_build_extern_static_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    use of extern static is unsafe and requires unsafe function or block
+    .note = extern statics are not controlled by the Rust type system: invalid data, aliasing violations or data races will cause undefined behavior
+    .label = use of extern static
+
+mir_build_deref_raw_pointer_requires_unsafe =
+    dereference of raw pointer is unsafe and requires unsafe block
+    .note = raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
+    .label = dereference of raw pointer
+
+mir_build_deref_raw_pointer_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    dereference of raw pointer is unsafe and requires unsafe function or block
+    .note = raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
+    .label = dereference of raw pointer
+
+mir_build_union_field_requires_unsafe =
+    access to union field is unsafe and requires unsafe block
+    .note = the field may not be properly initialized: using uninitialized data will cause undefined behavior
+    .label = access to union field
+
+mir_build_union_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    access to union field is unsafe and requires unsafe function or block
+    .note = the field may not be properly initialized: using uninitialized data will cause undefined behavior
+    .label = access to union field
+
+mir_build_mutation_of_layout_constrained_field_requires_unsafe =
+    mutation of layout constrained field is unsafe and requires unsafe block
+    .note = mutating layout constrained fields cannot statically be checked for valid values
+    .label = mutation of layout constrained field
+
+mir_build_mutation_of_layout_constrained_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    mutation of layout constrained field is unsafe and requires unsafe function or block
+    .note = mutating layout constrained fields cannot statically be checked for valid values
+    .label = mutation of layout constrained field
+
+mir_build_borrow_of_layout_constrained_field_requires_unsafe =
+    borrow of layout constrained field with interior mutability is unsafe and requires unsafe block
+    .note = references to fields of layout constrained fields lose the constraints. Coupled with interior mutability, the field can be changed to invalid values
+    .label = borrow of layout constrained field with interior mutability
+
+mir_build_borrow_of_layout_constrained_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    borrow of layout constrained field with interior mutability is unsafe and requires unsafe function or block
+    .note = references to fields of layout constrained fields lose the constraints. Coupled with interior mutability, the field can be changed to invalid values
+    .label = borrow of layout constrained field with interior mutability
+
+mir_build_call_to_fn_with_requires_unsafe =
+    call to function `{$function}` with `#[target_feature]` is unsafe and requires unsafe block
+    .note = can only be called if the required target features are available
+    .label = call to function with `#[target_feature]`
+
+mir_build_call_to_fn_with_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
+    call to function `{$function}` with `#[target_feature]` is unsafe and requires unsafe function or block
+    .note = can only be called if the required target features are available
+    .label = call to function with `#[target_feature]`
+
+mir_build_unused_unsafe = unnecessary `unsafe` block
+    .label = unnecessary `unsafe` block
+
+mir_build_unused_unsafe_enclosing_block_label = because it's nested under this `unsafe` block
+mir_build_unused_unsafe_enclosing_fn_label = because it's nested under this `unsafe` fn
+
+mir_build_non_exhaustive_patterns_type_not_empty = non-exhaustive patterns: type `{$ty}` is non-empty
+    .def_note = `{$peeled_ty}` defined here
+    .type_note = the matched value is of type `{$ty}`
+    .non_exhaustive_type_note = the matched value is of type `{$ty}`, which is marked as non-exhaustive
+    .reference_note = references are always considered inhabited
+    .suggestion = ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown
+    .help = ensure that all possible cases are being handled by adding a match arm with a wildcard pattern
+
+mir_build_static_in_pattern = statics cannot be referenced in patterns
+
+mir_build_assoc_const_in_pattern = associated consts cannot be referenced in patterns
+
+mir_build_const_param_in_pattern = const parameters cannot be referenced in patterns
+
+mir_build_non_const_path = runtime values cannot be referenced in patterns
+
+mir_build_unreachable_pattern = unreachable pattern
+    .label = unreachable pattern
+    .catchall_label = matches any value
+
+mir_build_const_pattern_depends_on_generic_parameter =
+    constant pattern depends on a generic parameter
+
+mir_build_could_not_eval_const_pattern = could not evaluate constant pattern
+
+mir_build_lower_range_bound_must_be_less_than_or_equal_to_upper =
+    lower range bound must be less than or equal to upper
+    .label = lower bound larger than upper bound
+    .teach_note = When matching against a range, the compiler verifies that the range is non-empty. Range patterns include both end-points, so this is equivalent to requiring the start of the range to be less than or equal to the end of the range.
+
+mir_build_lower_range_bound_must_be_less_than_upper = lower range bound must be less than upper
+
+mir_build_leading_irrefutable_let_patterns = leading irrefutable {$count ->
+        [one] pattern
+        *[other] patterns
+    } in let chain
+    .note = {$count ->
+        [one] this pattern
+        *[other] these patterns
+    } will always match
+    .help = consider moving {$count ->
+        [one] it
+        *[other] them
+    } outside of the construct
+
+mir_build_trailing_irrefutable_let_patterns = trailing irrefutable {$count ->
+        [one] pattern
+        *[other] patterns
+    } in let chain
+    .note = {$count ->
+        [one] this pattern
+        *[other] these patterns
+    } will always match
+    .help = consider moving {$count ->
+        [one] it
+        *[other] them
+    } into the body
+
+mir_build_bindings_with_variant_name =
+    pattern binding `{$ident}` is named the same as one of the variants of the type `{$ty_path}`
+    .suggestion = to match on the variant, qualify the path
+
+mir_build_irrefutable_let_patterns_generic_let = irrefutable `let` {$count ->
+        [one] pattern
+        *[other] patterns
+    }
+    .note = {$count ->
+        [one] this pattern
+        *[other] these patterns
+    } will always match, so the `let` is useless
+    .help = consider removing `let`
+
+mir_build_irrefutable_let_patterns_if_let = irrefutable `if let` {$count ->
+        [one] pattern
+        *[other] patterns
+    }
+    .note = {$count ->
+        [one] this pattern
+        *[other] these patterns
+    } will always match, so the `if let` is useless
+    .help = consider replacing the `if let` with a `let`
+
+mir_build_irrefutable_let_patterns_if_let_guard = irrefutable `if let` guard {$count ->
+        [one] pattern
+        *[other] patterns
+    }
+    .note = {$count ->
+        [one] this pattern
+        *[other] these patterns
+    } will always match, so the guard is useless
+    .help = consider removing the guard and adding a `let` inside the match arm
+
+mir_build_irrefutable_let_patterns_let_else = irrefutable `let...else` {$count ->
+        [one] pattern
+        *[other] patterns
+    }
+    .note = {$count ->
+        [one] this pattern
+        *[other] these patterns
+    } will always match, so the `else` clause is useless
+    .help = consider removing the `else` clause
+
+mir_build_irrefutable_let_patterns_while_let = irrefutable `while let` {$count ->
+        [one] pattern
+        *[other] patterns
+    }
+    .note = {$count ->
+        [one] this pattern
+        *[other] these patterns
+    } will always match, so the loop will never exit
+    .help = consider instead using a `loop {"{"} ... {"}"}` with a `let` inside it
+
+mir_build_borrow_of_moved_value = borrow of moved value
+    .label = value moved into `{$name}` here
+    .occurs_because_label = move occurs because `{$name}` has type `{$ty}` which does not implement the `Copy` trait
+    .value_borrowed_label = value borrowed here after move
+    .suggestion = borrow this binding in the pattern to avoid moving the value
+
+mir_build_multiple_mut_borrows = cannot borrow value as mutable more than once at a time
+    .label = first mutable borrow, by `{$name}`, occurs here
+    .mutable_borrow = another mutable borrow, by `{$name_mut}`, occurs here
+    .immutable_borrow = also borrowed as immutable, by `{$name_immut}`, here
+    .moved = also moved into `{$name_moved}` here
diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 418ba3c74d7..25d0e736e59 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -57,6 +57,7 @@ fluent_messages! {
     lint => "../locales/en-US/lint.ftl",
     metadata => "../locales/en-US/metadata.ftl",
     middle => "../locales/en-US/middle.ftl",
+    mir_build => "../locales/en-US/mir_build.ftl",
     mir_dataflow => "../locales/en-US/mir_dataflow.ftl",
     monomorphize => "../locales/en-US/monomorphize.ftl",
     parse => "../locales/en-US/parse.ftl",
diff --git a/compiler/rustc_mir_build/Cargo.toml b/compiler/rustc_mir_build/Cargo.toml
index 2baa3bfcb64..4ad3343d303 100644
--- a/compiler/rustc_mir_build/Cargo.toml
+++ b/compiler/rustc_mir_build/Cargo.toml
@@ -17,6 +17,7 @@ rustc_index = { path = "../rustc_index" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_infer = { path = "../rustc_infer" }
+rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index 3bb1f51650a..99e96ff77ce 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -1,7 +1,7 @@
 use crate::build::ExprCategory;
+use crate::errors::*;
 use rustc_middle::thir::visit::{self, Visitor};
 
-use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_middle::mir::BorrowKind;
 use rustc_middle::thir::*;
@@ -12,7 +12,6 @@ use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
 
-use std::borrow::Cow;
 use std::ops::Bound;
 
 struct UnsafetyVisitor<'a, 'tcx> {
@@ -46,7 +45,9 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
             self.warn_unused_unsafe(
                 hir_id,
                 block_span,
-                Some((self.tcx.sess.source_map().guess_head_span(enclosing_span), "block")),
+                Some(UnusedUnsafeEnclosing::Block {
+                    span: self.tcx.sess.source_map().guess_head_span(enclosing_span),
+                }),
             );
             f(self);
         } else {
@@ -60,7 +61,9 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
                     hir_id,
                     span,
                     if self.unsafe_op_in_unsafe_fn_allowed() {
-                        self.body_unsafety.unsafe_fn_sig_span().map(|span| (span, "fn"))
+                        self.body_unsafety
+                            .unsafe_fn_sig_span()
+                            .map(|span| UnusedUnsafeEnclosing::Function { span })
                     } else {
                         None
                     },
@@ -83,30 +86,11 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
             }
             SafetyContext::UnsafeFn if unsafe_op_in_unsafe_fn_allowed => {}
             SafetyContext::UnsafeFn => {
-                let (description, note) = kind.description_and_note(self.tcx);
                 // unsafe_op_in_unsafe_fn is disallowed
-                self.tcx.struct_span_lint_hir(
-                    UNSAFE_OP_IN_UNSAFE_FN,
-                    self.hir_context,
-                    span,
-                    format!("{} is unsafe and requires unsafe block (error E0133)", description,),
-                    |lint| lint.span_label(span, kind.simple_description()).note(note),
-                )
+                kind.emit_unsafe_op_in_unsafe_fn_lint(self.tcx, self.hir_context, span);
             }
             SafetyContext::Safe => {
-                let (description, note) = kind.description_and_note(self.tcx);
-                let fn_sugg = if unsafe_op_in_unsafe_fn_allowed { " function or" } else { "" };
-                struct_span_err!(
-                    self.tcx.sess,
-                    span,
-                    E0133,
-                    "{} is unsafe and requires unsafe{} block",
-                    description,
-                    fn_sugg,
-                )
-                .span_label(span, kind.simple_description())
-                .note(note)
-                .emit();
+                kind.emit_requires_unsafe_err(self.tcx, span, unsafe_op_in_unsafe_fn_allowed);
             }
         }
     }
@@ -115,17 +99,15 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
         &self,
         hir_id: hir::HirId,
         block_span: Span,
-        enclosing_unsafe: Option<(Span, &'static str)>,
+        enclosing_unsafe: Option<UnusedUnsafeEnclosing>,
     ) {
         let block_span = self.tcx.sess.source_map().guess_head_span(block_span);
-        let msg = "unnecessary `unsafe` block";
-        self.tcx.struct_span_lint_hir(UNUSED_UNSAFE, hir_id, block_span, msg, |lint| {
-            lint.span_label(block_span, msg);
-            if let Some((span, kind)) = enclosing_unsafe {
-                lint.span_label(span, format!("because it's nested under this `unsafe` {}", kind));
-            }
-            lint
-        });
+        self.tcx.emit_spanned_lint(
+            UNUSED_UNSAFE,
+            hir_id,
+            block_span,
+            UnusedUnsafe { span: block_span, enclosing: enclosing_unsafe },
+        );
     }
 
     /// Whether the `unsafe_op_in_unsafe_fn` lint is `allow`ed at the current HIR node.
@@ -536,81 +518,189 @@ enum UnsafeOpKind {
 use UnsafeOpKind::*;
 
 impl UnsafeOpKind {
-    pub fn simple_description(&self) -> &'static str {
-        match self {
-            CallToUnsafeFunction(..) => "call to unsafe function",
-            UseOfInlineAssembly => "use of inline assembly",
-            InitializingTypeWith => "initializing type with `rustc_layout_scalar_valid_range` attr",
-            UseOfMutableStatic => "use of mutable static",
-            UseOfExternStatic => "use of extern static",
-            DerefOfRawPointer => "dereference of raw pointer",
-            AccessToUnionField => "access to union field",
-            MutationOfLayoutConstrainedField => "mutation of layout constrained field",
-            BorrowOfLayoutConstrainedField => {
-                "borrow of layout constrained field with interior mutability"
-            }
-            CallToFunctionWith(..) => "call to function with `#[target_feature]`",
-        }
-    }
-
-    pub fn description_and_note(&self, tcx: TyCtxt<'_>) -> (Cow<'static, str>, &'static str) {
+    pub fn emit_unsafe_op_in_unsafe_fn_lint(
+        &self,
+        tcx: TyCtxt<'_>,
+        hir_id: hir::HirId,
+        span: Span,
+    ) {
         match self {
-            CallToUnsafeFunction(did) => (
-                if let Some(did) = did {
-                    Cow::from(format!("call to unsafe function `{}`", tcx.def_path_str(*did)))
-                } else {
-                    Cow::Borrowed(self.simple_description())
+            CallToUnsafeFunction(did) if did.is_some() => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafe {
+                    span,
+                    function: &tcx.def_path_str(did.unwrap()),
                 },
-                "consult the function's documentation for information on how to avoid undefined \
-                 behavior",
             ),
-            UseOfInlineAssembly => (
-                Cow::Borrowed(self.simple_description()),
-                "inline assembly is entirely unchecked and can cause undefined behavior",
+            CallToUnsafeFunction(..) => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafeNameless { span },
+            ),
+            UseOfInlineAssembly => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnUseOfInlineAssemblyRequiresUnsafe { span },
             ),
-            InitializingTypeWith => (
-                Cow::Borrowed(self.simple_description()),
-                "initializing a layout restricted type's field with a value outside the valid \
-                 range is undefined behavior",
+            InitializingTypeWith => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnInitializingTypeWithRequiresUnsafe { span },
             ),
-            UseOfMutableStatic => (
-                Cow::Borrowed(self.simple_description()),
-                "mutable statics can be mutated by multiple threads: aliasing violations or data \
-                 races will cause undefined behavior",
+            UseOfMutableStatic => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnUseOfMutableStaticRequiresUnsafe { span },
             ),
-            UseOfExternStatic => (
-                Cow::Borrowed(self.simple_description()),
-                "extern statics are not controlled by the Rust type system: invalid data, \
-                 aliasing violations or data races will cause undefined behavior",
+            UseOfExternStatic => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnUseOfExternStaticRequiresUnsafe { span },
             ),
-            DerefOfRawPointer => (
-                Cow::Borrowed(self.simple_description()),
-                "raw pointers may be null, dangling or unaligned; they can violate aliasing rules \
-                 and cause data races: all of these are undefined behavior",
+            DerefOfRawPointer => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnDerefOfRawPointerRequiresUnsafe { span },
             ),
-            AccessToUnionField => (
-                Cow::Borrowed(self.simple_description()),
-                "the field may not be properly initialized: using uninitialized data will cause \
-                 undefined behavior",
+            AccessToUnionField => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnAccessToUnionFieldRequiresUnsafe { span },
             ),
-            MutationOfLayoutConstrainedField => (
-                Cow::Borrowed(self.simple_description()),
-                "mutating layout constrained fields cannot statically be checked for valid values",
+            MutationOfLayoutConstrainedField => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnMutationOfLayoutConstrainedFieldRequiresUnsafe { span },
             ),
-            BorrowOfLayoutConstrainedField => (
-                Cow::Borrowed(self.simple_description()),
-                "references to fields of layout constrained fields lose the constraints. Coupled \
-                 with interior mutability, the field can be changed to invalid values",
+            BorrowOfLayoutConstrainedField => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnBorrowOfLayoutConstrainedFieldRequiresUnsafe { span },
             ),
-            CallToFunctionWith(did) => (
-                Cow::from(format!(
-                    "call to function `{}` with `#[target_feature]`",
-                    tcx.def_path_str(*did)
-                )),
-                "can only be called if the required target features are available",
+            CallToFunctionWith(did) => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnCallToFunctionWithRequiresUnsafe {
+                    span,
+                    function: &tcx.def_path_str(*did),
+                },
             ),
         }
     }
+
+    pub fn emit_requires_unsafe_err(
+        &self,
+        tcx: TyCtxt<'_>,
+        span: Span,
+        unsafe_op_in_unsafe_fn_allowed: bool,
+    ) {
+        match self {
+            CallToUnsafeFunction(did) if did.is_some() && unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    function: &tcx.def_path_str(did.unwrap()),
+                });
+            }
+            CallToUnsafeFunction(did) if did.is_some() => {
+                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafe {
+                    span,
+                    function: &tcx.def_path_str(did.unwrap()),
+                });
+            }
+            CallToUnsafeFunction(..) if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(
+                    CallToUnsafeFunctionRequiresUnsafeNamelessUnsafeOpInUnsafeFnAllowed { span },
+                );
+            }
+            CallToUnsafeFunction(..) => {
+                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafeNameless { span });
+            }
+            UseOfInlineAssembly if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(UseOfInlineAssemblyRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            UseOfInlineAssembly => {
+                tcx.sess.emit_err(UseOfInlineAssemblyRequiresUnsafe { span });
+            }
+            InitializingTypeWith if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(InitializingTypeWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            InitializingTypeWith => {
+                tcx.sess.emit_err(InitializingTypeWithRequiresUnsafe { span });
+            }
+            UseOfMutableStatic if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(UseOfMutableStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            UseOfMutableStatic => {
+                tcx.sess.emit_err(UseOfMutableStaticRequiresUnsafe { span });
+            }
+            UseOfExternStatic if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(UseOfExternStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            UseOfExternStatic => {
+                tcx.sess.emit_err(UseOfExternStaticRequiresUnsafe { span });
+            }
+            DerefOfRawPointer if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(DerefOfRawPointerRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            DerefOfRawPointer => {
+                tcx.sess.emit_err(DerefOfRawPointerRequiresUnsafe { span });
+            }
+            AccessToUnionField if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(AccessToUnionFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            AccessToUnionField => {
+                tcx.sess.emit_err(AccessToUnionFieldRequiresUnsafe { span });
+            }
+            MutationOfLayoutConstrainedField if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(
+                    MutationOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                        span,
+                    },
+                );
+            }
+            MutationOfLayoutConstrainedField => {
+                tcx.sess.emit_err(MutationOfLayoutConstrainedFieldRequiresUnsafe { span });
+            }
+            BorrowOfLayoutConstrainedField if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(
+                    BorrowOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span },
+                );
+            }
+            BorrowOfLayoutConstrainedField => {
+                tcx.sess.emit_err(BorrowOfLayoutConstrainedFieldRequiresUnsafe { span });
+            }
+            CallToFunctionWith(did) if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(CallToFunctionWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    function: &tcx.def_path_str(*did),
+                });
+            }
+            CallToFunctionWith(did) => {
+                tcx.sess.emit_err(CallToFunctionWithRequiresUnsafe {
+                    span,
+                    function: &tcx.def_path_str(*did),
+                });
+            }
+        }
+    }
 }
 
 pub fn check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalDefId>) {
diff --git a/compiler/rustc_mir_build/src/errors.rs b/compiler/rustc_mir_build/src/errors.rs
new file mode 100644
index 00000000000..68179001b91
--- /dev/null
+++ b/compiler/rustc_mir_build/src/errors.rs
@@ -0,0 +1,616 @@
+use crate::thir::pattern::MatchCheckCtxt;
+use rustc_errors::Handler;
+use rustc_errors::{
+    error_code, Applicability, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic, MultiSpan,
+};
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
+use rustc_middle::ty::{self, Ty};
+use rustc_span::{symbol::Ident, Span};
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unconditional_recursion)]
+#[help]
+pub struct UnconditionalRecursion {
+    #[label]
+    pub span: Span,
+    #[label(mir_build_unconditional_recursion_call_site_label)]
+    pub call_sites: Vec<Span>,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafe<'a> {
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe_nameless)]
+#[note]
+pub struct UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafeNameless {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_inline_assembly_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnUseOfInlineAssemblyRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_initializing_type_with_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnInitializingTypeWithRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_mutable_static_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnUseOfMutableStaticRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_extern_static_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnUseOfExternStaticRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_deref_raw_pointer_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnDerefOfRawPointerRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_union_field_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnAccessToUnionFieldRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_mutation_of_layout_constrained_field_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnMutationOfLayoutConstrainedFieldRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_borrow_of_layout_constrained_field_requires_unsafe)]
+pub struct UnsafeOpInUnsafeFnBorrowOfLayoutConstrainedFieldRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_fn_with_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnCallToFunctionWithRequiresUnsafe<'a> {
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_unsafe_fn_requires_unsafe, code = "E0133")]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafe<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_unsafe_fn_requires_unsafe_nameless, code = "E0133")]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafeNameless {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_unsafe_fn_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafeUnsafeOpInUnsafeFnAllowed<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_call_to_unsafe_fn_requires_unsafe_nameless_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafeNamelessUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_inline_assembly_requires_unsafe, code = "E0133")]
+#[note]
+pub struct UseOfInlineAssemblyRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_inline_assembly_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct UseOfInlineAssemblyRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_initializing_type_with_requires_unsafe, code = "E0133")]
+#[note]
+pub struct InitializingTypeWithRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_initializing_type_with_requires_unsafe_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct InitializingTypeWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_mutable_static_requires_unsafe, code = "E0133")]
+#[note]
+pub struct UseOfMutableStaticRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_mutable_static_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct UseOfMutableStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_extern_static_requires_unsafe, code = "E0133")]
+#[note]
+pub struct UseOfExternStaticRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_extern_static_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct UseOfExternStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_deref_raw_pointer_requires_unsafe, code = "E0133")]
+#[note]
+pub struct DerefOfRawPointerRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_deref_raw_pointer_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct DerefOfRawPointerRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_union_field_requires_unsafe, code = "E0133")]
+#[note]
+pub struct AccessToUnionFieldRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_union_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct AccessToUnionFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_mutation_of_layout_constrained_field_requires_unsafe, code = "E0133")]
+#[note]
+pub struct MutationOfLayoutConstrainedFieldRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_mutation_of_layout_constrained_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct MutationOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_borrow_of_layout_constrained_field_requires_unsafe, code = "E0133")]
+#[note]
+pub struct BorrowOfLayoutConstrainedFieldRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_borrow_of_layout_constrained_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct BorrowOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_fn_with_requires_unsafe, code = "E0133")]
+#[note]
+pub struct CallToFunctionWithRequiresUnsafe<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_fn_with_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct CallToFunctionWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unused_unsafe)]
+pub struct UnusedUnsafe {
+    #[label]
+    pub span: Span,
+    #[subdiagnostic]
+    pub enclosing: Option<UnusedUnsafeEnclosing>,
+}
+
+#[derive(Subdiagnostic)]
+pub enum UnusedUnsafeEnclosing {
+    #[label(mir_build_unused_unsafe_enclosing_block_label)]
+    Block {
+        #[primary_span]
+        span: Span,
+    },
+    #[label(mir_build_unused_unsafe_enclosing_fn_label)]
+    Function {
+        #[primary_span]
+        span: Span,
+    },
+}
+
+pub(crate) struct NonExhaustivePatternsTypeNotEmpty<'p, 'tcx, 'm> {
+    pub cx: &'m MatchCheckCtxt<'p, 'tcx>,
+    pub expr_span: Span,
+    pub span: Span,
+    pub ty: Ty<'tcx>,
+}
+
+impl<'a> IntoDiagnostic<'a> for NonExhaustivePatternsTypeNotEmpty<'_, '_, '_> {
+    fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
+        let mut diag = handler.struct_span_err_with_code(
+            self.span,
+            rustc_errors::fluent::mir_build_non_exhaustive_patterns_type_not_empty,
+            error_code!(E0004),
+        );
+
+        let peeled_ty = self.ty.peel_refs();
+        diag.set_arg("ty", self.ty);
+        diag.set_arg("peeled_ty", peeled_ty);
+
+        if let ty::Adt(def, _) = peeled_ty.kind() {
+            let def_span = self
+                .cx
+                .tcx
+                .hir()
+                .get_if_local(def.did())
+                .and_then(|node| node.ident())
+                .map(|ident| ident.span)
+                .unwrap_or_else(|| self.cx.tcx.def_span(def.did()));
+
+            // workaround to make test pass
+            let mut span: MultiSpan = def_span.into();
+            span.push_span_label(def_span, "");
+
+            diag.span_note(span, rustc_errors::fluent::def_note);
+        }
+
+        let is_variant_list_non_exhaustive = match self.ty.kind() {
+            ty::Adt(def, _) if def.is_variant_list_non_exhaustive() && !def.did().is_local() => {
+                true
+            }
+            _ => false,
+        };
+
+        if is_variant_list_non_exhaustive {
+            diag.note(rustc_errors::fluent::non_exhaustive_type_note);
+        } else {
+            diag.note(rustc_errors::fluent::type_note);
+        }
+
+        if let ty::Ref(_, sub_ty, _) = self.ty.kind() {
+            if !sub_ty.is_inhabited_from(self.cx.tcx, self.cx.module, self.cx.param_env) {
+                diag.note(rustc_errors::fluent::reference_note);
+            }
+        }
+
+        let mut suggestion = None;
+        let sm = self.cx.tcx.sess.source_map();
+        if self.span.eq_ctxt(self.expr_span) {
+            // Get the span for the empty match body `{}`.
+            let (indentation, more) = if let Some(snippet) = sm.indentation_before(self.span) {
+                (format!("\n{}", snippet), "    ")
+            } else {
+                (" ".to_string(), "")
+            };
+            suggestion = Some((
+                self.span.shrink_to_hi().with_hi(self.expr_span.hi()),
+                format!(
+                    " {{{indentation}{more}_ => todo!(),{indentation}}}",
+                    indentation = indentation,
+                    more = more,
+                ),
+            ));
+        }
+
+        if let Some((span, sugg)) = suggestion {
+            diag.span_suggestion_verbose(
+                span,
+                rustc_errors::fluent::suggestion,
+                sugg,
+                Applicability::HasPlaceholders,
+            );
+        } else {
+            diag.help(rustc_errors::fluent::help);
+        }
+
+        diag
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_static_in_pattern, code = "E0158")]
+pub struct StaticInPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_assoc_const_in_pattern, code = "E0158")]
+pub struct AssocConstInPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_const_param_in_pattern, code = "E0158")]
+pub struct ConstParamInPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_non_const_path, code = "E0080")]
+pub struct NonConstPath {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unreachable_pattern)]
+pub struct UnreachablePattern {
+    #[label]
+    pub span: Option<Span>,
+    #[label(catchall_label)]
+    pub catchall: Option<Span>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_const_pattern_depends_on_generic_parameter)]
+pub struct ConstPatternDependsOnGenericParameter {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_could_not_eval_const_pattern)]
+pub struct CouldNotEvalConstPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_lower_range_bound_must_be_less_than_or_equal_to_upper, code = "E0030")]
+pub struct LowerRangeBoundMustBeLessThanOrEqualToUpper {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    #[note(teach_note)]
+    pub teach: Option<()>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_lower_range_bound_must_be_less_than_upper, code = "E0579")]
+pub struct LowerRangeBoundMustBeLessThanUpper {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_leading_irrefutable_let_patterns)]
+#[note]
+#[help]
+pub struct LeadingIrrefutableLetPatterns {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_trailing_irrefutable_let_patterns)]
+#[note]
+#[help]
+pub struct TrailingIrrefutableLetPatterns {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_bindings_with_variant_name, code = "E0170")]
+pub struct BindingsWithVariantName {
+    #[suggestion(code = "{ty_path}::{ident}", applicability = "machine-applicable")]
+    pub suggestion: Option<Span>,
+    pub ty_path: String,
+    pub ident: Ident,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_generic_let)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsGenericLet {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_if_let)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsIfLet {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_if_let_guard)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsIfLetGuard {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_let_else)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsLetElse {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_while_let)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsWhileLet {
+    pub count: usize,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_borrow_of_moved_value)]
+pub struct BorrowOfMovedValue<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    #[label(occurs_because_label)]
+    pub binding_span: Span,
+    #[label(value_borrowed_label)]
+    pub conflicts_ref: Vec<Span>,
+    pub name: Ident,
+    pub ty: Ty<'tcx>,
+    #[suggestion(code = "ref ", applicability = "machine-applicable")]
+    pub suggest_borrowing: Option<Span>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_multiple_mut_borrows)]
+pub struct MultipleMutBorrows {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub binding_span: Span,
+    #[subdiagnostic]
+    pub occurences: Vec<MultipleMutBorrowOccurence>,
+    pub name: Ident,
+}
+
+#[derive(Subdiagnostic)]
+pub enum MultipleMutBorrowOccurence {
+    #[label(mutable_borrow)]
+    Mutable {
+        #[primary_span]
+        span: Span,
+        name_mut: Ident,
+    },
+    #[label(immutable_borrow)]
+    Immutable {
+        #[primary_span]
+        span: Span,
+        name_immut: Ident,
+    },
+    #[label(moved)]
+    Moved {
+        #[primary_span]
+        span: Span,
+        name_moved: Ident,
+    },
+}
diff --git a/compiler/rustc_mir_build/src/lib.rs b/compiler/rustc_mir_build/src/lib.rs
index 87975294595..2b05e92fdcf 100644
--- a/compiler/rustc_mir_build/src/lib.rs
+++ b/compiler/rustc_mir_build/src/lib.rs
@@ -19,6 +19,7 @@ extern crate rustc_middle;
 
 mod build;
 mod check_unsafety;
+mod errors;
 mod lints;
 pub mod thir;
 
diff --git a/compiler/rustc_mir_build/src/lints.rs b/compiler/rustc_mir_build/src/lints.rs
index b21f30efce8..8529c64cd5c 100644
--- a/compiler/rustc_mir_build/src/lints.rs
+++ b/compiler/rustc_mir_build/src/lints.rs
@@ -1,3 +1,4 @@
+use crate::errors::UnconditionalRecursion;
 use rustc_data_structures::graph::iterate::{
     NodeStatus, TriColorDepthFirstSearch, TriColorVisitor,
 };
@@ -36,19 +37,11 @@ pub(crate) fn check<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
 
         let sp = tcx.def_span(def_id);
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-        tcx.struct_span_lint_hir(
+        tcx.emit_spanned_lint(
             UNCONDITIONAL_RECURSION,
             hir_id,
             sp,
-            "function cannot return without recursing",
-            |lint| {
-                lint.span_label(sp, "cannot return without recursing");
-                // offer some help to the programmer.
-                for call_span in vis.reachable_recursive_calls {
-                    lint.span_label(call_span, "recursive call site");
-                }
-                lint.help("a `loop` may express intention better if this is on purpose")
-            },
+            UnconditionalRecursion { span: sp, call_sites: vis.reachable_recursive_calls },
         );
     }
 }
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
index e369dba5524..a94d8d6c643 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -4,18 +4,22 @@ use super::usefulness::{
 };
 use super::{PatCtxt, PatternError};
 
+use crate::errors::*;
+
 use rustc_arena::TypedArena;
 use rustc_ast::Mutability;
 use rustc_errors::{
-    error_code, pluralize, struct_span_err, Applicability, DelayDm, Diagnostic, DiagnosticBuilder,
-    ErrorGuaranteed, MultiSpan,
+    pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
+    MultiSpan,
 };
 use rustc_hir as hir;
 use rustc_hir::def::*;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{HirId, Pat};
+use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
+
 use rustc_session::lint::builtin::{
     BINDINGS_WITH_VARIANT_NAME, IRREFUTABLE_LET_PATTERNS, UNREACHABLE_PATTERNS,
 };
@@ -107,28 +111,20 @@ impl PatCtxt<'_, '_> {
         for error in &self.errors {
             match *error {
                 PatternError::StaticInPattern(span) => {
-                    self.span_e0158(span, "statics cannot be referenced in patterns")
+                    self.tcx.sess.emit_err(StaticInPattern { span });
                 }
                 PatternError::AssocConstInPattern(span) => {
-                    self.span_e0158(span, "associated consts cannot be referenced in patterns")
+                    self.tcx.sess.emit_err(AssocConstInPattern { span });
                 }
                 PatternError::ConstParamInPattern(span) => {
-                    self.span_e0158(span, "const parameters cannot be referenced in patterns")
+                    self.tcx.sess.emit_err(ConstParamInPattern { span });
                 }
                 PatternError::NonConstPath(span) => {
-                    rustc_middle::mir::interpret::struct_error(
-                        self.tcx.at(span),
-                        "runtime values cannot be referenced in patterns",
-                    )
-                    .emit();
+                    self.tcx.sess.emit_err(NonConstPath { span });
                 }
             }
         }
     }
-
-    fn span_e0158(&self, span: Span, text: &str) {
-        struct_span_err!(self.tcx.sess, span, E0158, "{}", text).emit();
-    }
 }
 
 impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
@@ -345,29 +341,6 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
             );
             return true;
         }
-        let lint_affix = |affix: &[Option<(Span, bool)>], kind, suggestion| {
-            let span_start = affix[0].unwrap().0;
-            let span_end = affix.last().unwrap().unwrap().0;
-            let span = span_start.to(span_end);
-            let cnt = affix.len();
-            let s = pluralize!(cnt);
-            cx.tcx.struct_span_lint_hir(
-                IRREFUTABLE_LET_PATTERNS,
-                top,
-                span,
-                format!("{kind} irrefutable pattern{s} in let chain"),
-                |lint| {
-                    lint.note(format!(
-                        "{these} pattern{s} will always match",
-                        these = pluralize!("this", cnt),
-                    ))
-                    .help(format!(
-                        "consider moving {} {suggestion}",
-                        if cnt > 1 { "them" } else { "it" }
-                    ))
-                },
-            );
-        };
         if let Some(until) = chain_refutabilities.iter().position(|r| !matches!(*r, Some((_, false)))) && until > 0 {
             // The chain has a non-zero prefix of irrefutable `let` statements.
 
@@ -381,13 +354,21 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
             if !matches!(let_source, LetSource::WhileLet | LetSource::IfLetGuard) {
                 // Emit the lint
                 let prefix = &chain_refutabilities[..until];
-                lint_affix(prefix, "leading", "outside of the construct");
+                let span_start = prefix[0].unwrap().0;
+                let span_end = prefix.last().unwrap().unwrap().0;
+                let span = span_start.to(span_end);
+                let count = prefix.len();
+                cx.tcx.emit_spanned_lint(IRREFUTABLE_LET_PATTERNS, top, span, LeadingIrrefutableLetPatterns { count });
             }
         }
         if let Some(from) = chain_refutabilities.iter().rposition(|r| !matches!(*r, Some((_, false)))) && from != (chain_refutabilities.len() - 1) {
             // The chain has a non-empty suffix of irrefutable `let` statements
             let suffix = &chain_refutabilities[from + 1..];
-            lint_affix(suffix, "trailing", "into the body");
+            let span_start = suffix[0].unwrap().0;
+            let span_end = suffix.last().unwrap().unwrap().0;
+            let span = span_start.to(span_end);
+            let count = suffix.len();
+            cx.tcx.emit_spanned_lint(IRREFUTABLE_LET_PATTERNS, top, span, TrailingIrrefutableLetPatterns { count });
         }
         true
     }
@@ -568,32 +549,22 @@ fn check_for_bindings_named_same_as_variants(
             })
         {
             let variant_count = edef.variants().len();
-            cx.tcx.struct_span_lint_hir(
+            let ty_path = with_no_trimmed_paths!({
+                cx.tcx.def_path_str(edef.did())
+            });
+            cx.tcx.emit_spanned_lint(
                 BINDINGS_WITH_VARIANT_NAME,
                 p.hir_id,
                 p.span,
-                DelayDm(|| format!(
-                    "pattern binding `{}` is named the same as one \
-                        of the variants of the type `{}`",
-                    ident, cx.tcx.def_path_str(edef.did())
-                )),
-                |lint| {
-                    let ty_path = cx.tcx.def_path_str(edef.did());
-                    lint.code(error_code!(E0170));
-
+                BindingsWithVariantName {
                     // If this is an irrefutable pattern, and there's > 1 variant,
                     // then we can't actually match on this. Applying the below
                     // suggestion would produce code that breaks on `check_irrefutable`.
-                    if rf == Refutable || variant_count == 1 {
-                        lint.span_suggestion(
-                            p.span,
-                            "to match on the variant, qualify the path",
-                            format!("{}::{}", ty_path, ident),
-                            Applicability::MachineApplicable,
-                        );
-                    }
-
-                    lint
+                    suggestion: if rf == Refutable || variant_count == 1 {
+                        Some(p.span)
+                    } else { None },
+                    ty_path,
+                    ident,
                 },
             )
         }
@@ -611,14 +582,12 @@ fn pat_is_catchall(pat: &DeconstructedPat<'_, '_>) -> bool {
 }
 
 fn unreachable_pattern(tcx: TyCtxt<'_>, span: Span, id: HirId, catchall: Option<Span>) {
-    tcx.struct_span_lint_hir(UNREACHABLE_PATTERNS, id, span, "unreachable pattern", |lint| {
-        if let Some(catchall) = catchall {
-            // We had a catchall pattern, hint at that.
-            lint.span_label(span, "unreachable pattern");
-            lint.span_label(catchall, "matches any value");
-        }
-        lint
-    });
+    tcx.emit_spanned_lint(
+        UNREACHABLE_PATTERNS,
+        id,
+        span,
+        UnreachablePattern { span: if catchall.is_some() { Some(span) } else { None }, catchall },
+    );
 }
 
 fn irrefutable_let_pattern(tcx: TyCtxt<'_>, id: HirId, span: Span) {
@@ -634,67 +603,18 @@ fn irrefutable_let_patterns(
     span: Span,
 ) {
     macro_rules! emit_diag {
-        (
-            $lint:expr,
-            $source_name:expr,
-            $note_sufix:expr,
-            $help_sufix:expr
-        ) => {{
-            let s = pluralize!(count);
-            let these = pluralize!("this", count);
-            tcx.struct_span_lint_hir(
-                IRREFUTABLE_LET_PATTERNS,
-                id,
-                span,
-                format!("irrefutable {} pattern{s}", $source_name),
-                |lint| {
-                    lint.note(&format!(
-                        "{these} pattern{s} will always match, so the {}",
-                        $note_sufix
-                    ))
-                    .help(concat!("consider ", $help_sufix))
-                },
-            )
+        ($lint:tt) => {{
+            tcx.emit_spanned_lint(IRREFUTABLE_LET_PATTERNS, id, span, $lint { count });
         }};
     }
 
     match source {
-        LetSource::GenericLet => {
-            emit_diag!(lint, "`let`", "`let` is useless", "removing `let`");
-        }
-        LetSource::IfLet => {
-            emit_diag!(
-                lint,
-                "`if let`",
-                "`if let` is useless",
-                "replacing the `if let` with a `let`"
-            );
-        }
-        LetSource::IfLetGuard => {
-            emit_diag!(
-                lint,
-                "`if let` guard",
-                "guard is useless",
-                "removing the guard and adding a `let` inside the match arm"
-            );
-        }
-        LetSource::LetElse => {
-            emit_diag!(
-                lint,
-                "`let...else`",
-                "`else` clause is useless",
-                "removing the `else` clause"
-            );
-        }
-        LetSource::WhileLet => {
-            emit_diag!(
-                lint,
-                "`while let`",
-                "loop will never exit",
-                "instead using a `loop { ... }` with a `let` inside it"
-            );
-        }
-    };
+        LetSource::GenericLet => emit_diag!(IrrefutableLetPatternsGenericLet),
+        LetSource::IfLet => emit_diag!(IrrefutableLetPatternsIfLet),
+        LetSource::IfLetGuard => emit_diag!(IrrefutableLetPatternsIfLetGuard),
+        LetSource::LetElse => emit_diag!(IrrefutableLetPatternsLetElse),
+        LetSource::WhileLet => emit_diag!(IrrefutableLetPatternsWhileLet),
+    }
 }
 
 fn is_let_irrefutable<'p, 'tcx>(
@@ -760,15 +680,17 @@ fn non_exhaustive_match<'p, 'tcx>(
     // informative.
     let mut err;
     let pattern;
-    let mut patterns_len = 0;
+    let patterns_len;
     if is_empty_match && !non_empty_enum {
-        err = create_e0004(
-            cx.tcx.sess,
-            sp,
-            format!("non-exhaustive patterns: type `{}` is non-empty", scrut_ty),
-        );
-        pattern = "_".to_string();
+        cx.tcx.sess.emit_err(NonExhaustivePatternsTypeNotEmpty {
+            cx,
+            expr_span,
+            span: sp,
+            ty: scrut_ty,
+        });
+        return;
     } else {
+        // FIXME: migration of this diagnostic will require list support
         let joined_patterns = joined_uncovered_patterns(cx, &witnesses);
         err = create_e0004(
             cx.tcx.sess,
@@ -1039,24 +961,17 @@ fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_, '_>, pat: &Pa
                 }
             });
             if !conflicts_ref.is_empty() {
-                let occurs_because = format!(
-                    "move occurs because `{}` has type `{}` which does not implement the `Copy` trait",
+                sess.emit_err(BorrowOfMovedValue {
+                    span: pat.span,
+                    binding_span,
+                    conflicts_ref,
                     name,
-                    typeck_results.node_type(pat.hir_id),
-                );
-                let mut err = sess.struct_span_err(pat.span, "borrow of moved value");
-                err.span_label(binding_span, format!("value moved into `{}` here", name))
-                    .span_label(binding_span, occurs_because)
-                    .span_labels(conflicts_ref, "value borrowed here after move");
-                if pat.span.contains(binding_span) {
-                    err.span_suggestion_verbose(
-                        binding_span.shrink_to_lo(),
-                        "borrow this binding in the pattern to avoid moving the value",
-                        "ref ".to_string(),
-                        Applicability::MachineApplicable,
-                    );
-                }
-                err.emit();
+                    ty: typeck_results.node_type(pat.hir_id),
+                    suggest_borrowing: pat
+                        .span
+                        .contains(binding_span)
+                        .then(|| binding_span.shrink_to_lo()),
+                });
             }
             return;
         }
@@ -1086,19 +1001,18 @@ fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_, '_>, pat: &Pa
     // Report errors if any.
     if !conflicts_mut_mut.is_empty() {
         // Report mutability conflicts for e.g. `ref mut x @ Some(ref mut y)`.
-        let mut err = sess
-            .struct_span_err(pat.span, "cannot borrow value as mutable more than once at a time");
-        err.span_label(binding_span, format!("first mutable borrow, by `{}`, occurs here", name));
-        for (span, name) in conflicts_mut_mut {
-            err.span_label(span, format!("another mutable borrow, by `{}`, occurs here", name));
+        let mut occurences = vec![];
+
+        for (span, name_mut) in conflicts_mut_mut {
+            occurences.push(MultipleMutBorrowOccurence::Mutable { span, name_mut });
         }
-        for (span, name) in conflicts_mut_ref {
-            err.span_label(span, format!("also borrowed as immutable, by `{}`, here", name));
+        for (span, name_immut) in conflicts_mut_ref {
+            occurences.push(MultipleMutBorrowOccurence::Immutable { span, name_immut });
         }
-        for (span, name) in conflicts_move {
-            err.span_label(span, format!("also moved into `{}` here", name));
+        for (span, name_moved) in conflicts_move {
+            occurences.push(MultipleMutBorrowOccurence::Moved { span, name_moved });
         }
-        err.emit();
+        sess.emit_err(MultipleMutBorrows { span: pat.span, binding_span, occurences, name });
     } else if !conflicts_mut_ref.is_empty() {
         // Report mutability conflicts for e.g. `ref x @ Some(ref mut y)` or the converse.
         let (primary, also) = match mut_outer {
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index 48a231a6cd6..2c775b39718 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -6,10 +6,12 @@ mod deconstruct_pat;
 mod usefulness;
 
 pub(crate) use self::check_match::check_match;
+pub(crate) use self::usefulness::MatchCheckCtxt;
 
+use crate::errors::*;
 use crate::thir::util::UserAnnotatedTyHelpers;
 
-use rustc_errors::struct_span_err;
+use rustc_errors::error_code;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::pat_util::EnumerateAndAdjustIterator;
@@ -139,13 +141,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
             // `x..y` where `x >= y`. The range is empty => error.
             (RangeEnd::Excluded, _) => {
-                struct_span_err!(
-                    self.tcx.sess,
-                    span,
-                    E0579,
-                    "lower range bound must be less than upper"
-                )
-                .emit();
+                self.tcx.sess.emit_err(LowerRangeBoundMustBeLessThanUpper { span });
                 PatKind::Wild
             }
             // `x..=y` where `x == y`.
@@ -156,23 +152,10 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
             // `x..=y` where `x > y` hence the range is empty => error.
             (RangeEnd::Included, _) => {
-                let mut err = struct_span_err!(
-                    self.tcx.sess,
+                self.tcx.sess.emit_err(LowerRangeBoundMustBeLessThanOrEqualToUpper {
                     span,
-                    E0030,
-                    "lower range bound must be less than or equal to upper"
-                );
-                err.span_label(span, "lower bound larger than upper bound");
-                if self.tcx.sess.teach(&err.get_code().unwrap()) {
-                    err.note(
-                        "When matching against a range, the compiler \
-                              verifies that the range is non-empty. Range \
-                              patterns include both end-points, so this is \
-                              equivalent to requiring the start of the range \
-                              to be less than or equal to the end of the range.",
-                    );
-                }
-                err.emit();
+                    teach: if self.tcx.sess.teach(&error_code!(E0030)) { Some(()) } else { None },
+                });
                 PatKind::Wild
             }
         }
@@ -501,7 +484,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
 
             Err(_) => {
-                self.tcx.sess.span_err(span, "could not evaluate constant pattern");
+                self.tcx.sess.emit_err(CouldNotEvalConstPattern { span });
                 return pat_from_kind(PatKind::Wild);
             }
         };
@@ -548,11 +531,11 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             Err(ErrorHandled::TooGeneric) => {
                 // While `Reported | Linted` cases will have diagnostics emitted already
                 // it is not true for TooGeneric case, so we need to give user more information.
-                self.tcx.sess.span_err(span, "constant pattern depends on a generic parameter");
+                self.tcx.sess.emit_err(ConstPatternDependsOnGenericParameter { span });
                 pat_from_kind(PatKind::Wild)
             }
             Err(_) => {
-                self.tcx.sess.span_err(span, "could not evaluate constant pattern");
+                self.tcx.sess.emit_err(CouldNotEvalConstPattern { span });
                 pat_from_kind(PatKind::Wild)
             }
         }
@@ -584,7 +567,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             mir::ConstantKind::Val(_, _) => self.const_to_pat(value, id, span, false).kind,
             mir::ConstantKind::Unevaluated(..) => {
                 // If we land here it means the const can't be evaluated because it's `TooGeneric`.
-                self.tcx.sess.span_err(span, "constant pattern depends on a generic parameter");
+                self.tcx.sess.emit_err(ConstPatternDependsOnGenericParameter { span });
                 return PatKind::Wild;
             }
         }
diff --git a/src/test/ui/lint/lint-uppercase-variables.rs b/src/test/ui/lint/lint-uppercase-variables.rs
index b590fa697ad..d4e88aa2643 100644
--- a/src/test/ui/lint/lint-uppercase-variables.rs
+++ b/src/test/ui/lint/lint-uppercase-variables.rs
@@ -20,19 +20,19 @@ fn main() {
 
     match foo::Foo::Foo {
         Foo => {}
-//~^ ERROR variable `Foo` should have a snake case name
-//~^^ WARN `Foo` is named the same as one of the variants of the type `Foo`
-//~^^^ WARN unused variable: `Foo`
+    //~^ ERROR variable `Foo` should have a snake case name
+    //~^^ WARN `Foo` is named the same as one of the variants of the type `foo::Foo`
+    //~^^^ WARN unused variable: `Foo`
     }
 
     let Foo = foo::Foo::Foo;
     //~^ ERROR variable `Foo` should have a snake case name
-    //~^^ WARN `Foo` is named the same as one of the variants of the type `Foo`
+    //~^^ WARN `Foo` is named the same as one of the variants of the type `foo::Foo`
     //~^^^ WARN unused variable: `Foo`
 
     fn in_param(Foo: foo::Foo) {}
     //~^ ERROR variable `Foo` should have a snake case name
-    //~^^ WARN `Foo` is named the same as one of the variants of the type `Foo`
+    //~^^ WARN `Foo` is named the same as one of the variants of the type `foo::Foo`
     //~^^^ WARN unused variable: `Foo`
 
     test(1);
diff --git a/src/test/ui/lint/lint-uppercase-variables.stderr b/src/test/ui/lint/lint-uppercase-variables.stderr
index 71b24a835bc..d476d856e24 100644
--- a/src/test/ui/lint/lint-uppercase-variables.stderr
+++ b/src/test/ui/lint/lint-uppercase-variables.stderr
@@ -1,22 +1,22 @@
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `Foo`
+warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:22:9
    |
 LL |         Foo => {}
-   |         ^^^ help: to match on the variant, qualify the path: `Foo::Foo`
+   |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
    |
    = note: `#[warn(bindings_with_variant_name)]` on by default
 
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `Foo`
+warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:28:9
    |
 LL |     let Foo = foo::Foo::Foo;
-   |         ^^^ help: to match on the variant, qualify the path: `Foo::Foo`
+   |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
 
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `Foo`
+warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:33:17
    |
 LL |     fn in_param(Foo: foo::Foo) {}
-   |                 ^^^ help: to match on the variant, qualify the path: `Foo::Foo`
+   |                 ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
 
 warning: unused variable: `Foo`
   --> $DIR/lint-uppercase-variables.rs:22:9