Auto merge of #102509 - matthiaskrgr:rollup-gtenet8, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #101075 (Migrate rustc_codegen_gcc to SessionDiagnostics )
 - #102350 (Improve errors for incomplete functions in struct definitions)
 - #102481 (rustdoc: remove unneeded CSS `.rust-example-rendered { position }`)
 - #102491 (rustdoc: remove no-op source sidebar `opacity`)
 - #102499 (Adjust the s390x data layout for LLVM 16)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

8 files changed, 322 insertions, 163 deletions

diff --git a/compiler/rustc_codegen_gcc/src/archive.rs b/compiler/rustc_codegen_gcc/src/archive.rs
index f863abdcc97..ac0342f6b80 100644
--- a/compiler/rustc_codegen_gcc/src/archive.rs
+++ b/compiler/rustc_codegen_gcc/src/archive.rs
@@ -1,6 +1,8 @@
 use std::fs::File;
 use std::path::{Path, PathBuf};
 
+use crate::errors::RanlibFailure;
+
 use rustc_codegen_ssa::back::archive::{ArchiveBuilder, ArchiveBuilderBuilder};
 use rustc_session::Session;
 
@@ -181,7 +183,7 @@ impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
             std::process::Command::new("ranlib").arg(output).status().expect("Couldn't run ranlib");
 
         if !status.success() {
-            self.config.sess.fatal(&format!("Ranlib exited with code {:?}", status.code()));
+            self.config.sess.emit_fatal(RanlibFailure::new(status.code()));
         }
 
         any_members
diff --git a/compiler/rustc_codegen_gcc/src/asm.rs b/compiler/rustc_codegen_gcc/src/asm.rs
index 52fd66af065..007b001f213 100644
--- a/compiler/rustc_codegen_gcc/src/asm.rs
+++ b/compiler/rustc_codegen_gcc/src/asm.rs
@@ -12,6 +12,7 @@ use std::borrow::Cow;
 
 use crate::builder::Builder;
 use crate::context::CodegenCx;
+use crate::errors::UnwindingInlineAsm;
 use crate::type_of::LayoutGccExt;
 use crate::callee::get_fn;
 
@@ -109,7 +110,7 @@ impl<'a, 'gcc, 'tcx> AsmBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
     fn codegen_inline_asm(&mut self, template: &[InlineAsmTemplatePiece], rust_operands: &[InlineAsmOperandRef<'tcx, Self>], options: InlineAsmOptions, span: &[Span], _instance: Instance<'_>, _dest_catch_funclet: Option<(Self::BasicBlock, Self::BasicBlock, Option<&Self::Funclet>)>) {
         if options.contains(InlineAsmOptions::MAY_UNWIND) {
             self.sess()
-                .struct_span_err(span[0], "GCC backend does not support unwinding from inline asm")
+                .create_err(UnwindingInlineAsm { span: span[0] })
                 .emit();
             return;
         }
diff --git a/compiler/rustc_codegen_gcc/src/consts.rs b/compiler/rustc_codegen_gcc/src/consts.rs
index 356c03ee3c1..81f53328867 100644
--- a/compiler/rustc_codegen_gcc/src/consts.rs
+++ b/compiler/rustc_codegen_gcc/src/consts.rs
@@ -14,6 +14,7 @@ use rustc_target::abi::{self, Align, HasDataLayout, Primitive, Size, WrappingRan
 
 use crate::base;
 use crate::context::CodegenCx;
+use crate::errors::LinkageConstOrMutType;
 use crate::type_of::LayoutGccExt;
 
 impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
@@ -368,10 +369,7 @@ fn check_and_apply_linkage<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, attrs: &Codeg
                 cx.layout_of(mt.ty).gcc_type(cx, true)
             }
             else {
-                cx.sess().span_fatal(
-                    span,
-                    "must have type `*const T` or `*mut T` due to `#[linkage]` attribute",
-                )
+                cx.sess().emit_fatal(LinkageConstOrMutType { span: span })
             };
         // Declare a symbol `foo` with the desired linkage.
         let global1 = cx.declare_global_with_linkage(&sym, llty2, base::global_linkage_to_gcc(linkage));
diff --git a/compiler/rustc_codegen_gcc/src/context.rs b/compiler/rustc_codegen_gcc/src/context.rs
index 478f6d893dd..46ade33eb01 100644
--- a/compiler/rustc_codegen_gcc/src/context.rs
+++ b/compiler/rustc_codegen_gcc/src/context.rs
@@ -13,7 +13,7 @@ use rustc_middle::mir::mono::CodegenUnit;
 use rustc_middle::ty::{self, Instance, ParamEnv, PolyExistentialTraitRef, Ty, TyCtxt};
 use rustc_middle::ty::layout::{FnAbiError, FnAbiOfHelpers, FnAbiRequest, HasParamEnv, HasTyCtxt, LayoutError, TyAndLayout, LayoutOfHelpers};
 use rustc_session::Session;
-use rustc_span::Span;
+use rustc_span::{Span, source_map::respan};
 use rustc_target::abi::{call::FnAbi, HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx};
 use rustc_target::spec::{HasTargetSpec, Target, TlsModel};
 
@@ -293,7 +293,7 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
         self.is_native_int_type(typ) || self.is_non_native_int_type(typ) || typ.is_compatible_with(self.bool_type)
     }
 
-    pub fn sess(&self) -> &Session {
+    pub fn sess(&self) -> &'tcx Session {
         &self.tcx.sess
     }
 
@@ -477,7 +477,7 @@ impl<'gcc, 'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
     #[inline]
     fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {
         if let LayoutError::SizeOverflow(_) = err {
-            self.sess().span_fatal(span, &err.to_string())
+            self.sess().emit_fatal(respan(span, err))
         } else {
             span_bug!(span, "failed to get layout for `{}`: {}", ty, err)
         }
@@ -495,7 +495,7 @@ impl<'gcc, 'tcx> FnAbiOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
         fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
         if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
-            self.sess().span_fatal(span, &err.to_string())
+            self.sess().emit_fatal(respan(span, err))
         } else {
             match fn_abi_request {
                 FnAbiRequest::OfFnPtr { sig, extra_args } => {
diff --git a/compiler/rustc_codegen_gcc/src/errors.rs b/compiler/rustc_codegen_gcc/src/errors.rs
new file mode 100644
index 00000000000..d7816e395c8
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/errors.rs
@@ -0,0 +1,242 @@
+use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
+use rustc_macros::Diagnostic;
+use rustc_middle::ty::Ty;
+use rustc_span::{Span, Symbol};
+use std::borrow::Cow;
+
+struct ExitCode(Option<i32>);
+
+impl IntoDiagnosticArg for ExitCode {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        let ExitCode(exit_code) = self;
+        match exit_code {
+            Some(t) => t.into_diagnostic_arg(),
+            None => DiagnosticArgValue::Str(Cow::Borrowed("<signal>")),
+        }
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::ranlib_failure)]
+pub(crate) struct RanlibFailure {
+    exit_code: ExitCode,
+}
+
+impl RanlibFailure {
+    pub fn new(exit_code: Option<i32>) -> Self {
+        RanlibFailure { exit_code: ExitCode(exit_code) }
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_basic_integer, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationBasicInteger<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_invalid_float_vector, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationInvalidFloatVector<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub elem_ty: &'a str,
+    pub vec_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_not_float, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationNotFloat<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_unrecognized, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationUnrecognized {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_expected_signed_unsigned, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationExpectedSignedUnsigned<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub elem_ty: Ty<'a>,
+    pub vec_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_unsupported_element, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationUnsupportedElement<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_ty: Ty<'a>,
+    pub elem_ty: Ty<'a>,
+    pub ret_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_invalid_bitmask, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationInvalidBitmask<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub ty: Ty<'a>,
+    pub expected_int_bits: u64,
+    pub expected_bytes: u64,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_simd_shuffle, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationSimdShuffle<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_expected_simd, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationExpectedSimd<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub position: &'a str,
+    pub found_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_mask_type, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationMaskType<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_return_length, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationReturnLength<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_len: u64,
+    pub ret_ty: Ty<'a>,
+    pub out_len: u64,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_return_length_input_type, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationReturnLengthInputType<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_len: u64,
+    pub in_ty: Ty<'a>,
+    pub ret_ty: Ty<'a>,
+    pub out_len: u64,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_return_element, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationReturnElement<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_elem: Ty<'a>,
+    pub in_ty: Ty<'a>,
+    pub ret_ty: Ty<'a>,
+    pub out_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_return_type, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationReturnType<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_elem: Ty<'a>,
+    pub in_ty: Ty<'a>,
+    pub ret_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_inserted_type, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationInsertedType<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_elem: Ty<'a>,
+    pub in_ty: Ty<'a>,
+    pub out_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_return_integer_type, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationReturnIntegerType<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub ret_ty: Ty<'a>,
+    pub out_ty: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_mismatched_lengths, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationMismatchedLengths {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub m_len: u64,
+    pub v_len: u64,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_unsupported_cast, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationUnsupportedCast<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_ty: Ty<'a>,
+    pub in_elem: Ty<'a>,
+    pub ret_ty: Ty<'a>,
+    pub out_elem: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::invalid_monomorphization_unsupported_operation, code = "E0511")]
+pub(crate) struct InvalidMonomorphizationUnsupportedOperation<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+    pub in_ty: Ty<'a>,
+    pub in_elem: Ty<'a>,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::linkage_const_or_mut_type)]
+pub(crate) struct LinkageConstOrMutType {
+    #[primary_span]
+    pub span: Span
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::lto_not_supported)]
+pub(crate) struct LTONotSupported;
+
+#[derive(Diagnostic)]
+#[diag(codegen_gcc::unwinding_inline_asm)]
+pub(crate) struct UnwindingInlineAsm {
+    #[primary_span]
+    pub span: Span
+}
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
index 02cedd4646b..cc9c90c2427 100644
--- a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
@@ -4,7 +4,7 @@ mod simd;
 use gccjit::{ComparisonOp, Function, RValue, ToRValue, Type, UnaryOp, FunctionType};
 use rustc_codegen_ssa::MemFlags;
 use rustc_codegen_ssa::base::wants_msvc_seh;
-use rustc_codegen_ssa::common::{IntPredicate, span_invalid_monomorphization_error};
+use rustc_codegen_ssa::common::IntPredicate;
 use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::traits::{ArgAbiMethods, BaseTypeMethods, BuilderMethods, ConstMethods, IntrinsicCallMethods};
@@ -20,6 +20,7 @@ use crate::abi::GccType;
 use crate::builder::Builder;
 use crate::common::{SignType, TypeReflection};
 use crate::context::CodegenCx;
+use crate::errors::InvalidMonomorphizationBasicInteger;
 use crate::type_of::LayoutGccExt;
 use crate::intrinsic::simd::generic_simd_intrinsic;
 
@@ -242,15 +243,7 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
                                 _ => bug!(),
                             },
                             None => {
-                                span_invalid_monomorphization_error(
-                                    tcx.sess,
-                                    span,
-                                    &format!(
-                                        "invalid monomorphization of `{}` intrinsic: \
-                                      expected basic integer type, found `{}`",
-                                      name, ty
-                                    ),
-                                );
+                                tcx.sess.emit_err(InvalidMonomorphizationBasicInteger { span, name, ty });
                                 return;
                             }
                         }
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs b/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
index 2401f335018..ffc85b773a2 100644
--- a/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
@@ -2,7 +2,7 @@ use std::cmp::Ordering;
 
 use gccjit::{BinaryOp, RValue, Type, ToRValue};
 use rustc_codegen_ssa::base::compare_simd_types;
-use rustc_codegen_ssa::common::{TypeKind, span_invalid_monomorphization_error};
+use rustc_codegen_ssa::common::TypeKind;
 use rustc_codegen_ssa::mir::operand::OperandRef;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::traits::{BaseTypeMethods, BuilderMethods};
@@ -14,43 +14,48 @@ use rustc_span::{Span, Symbol, sym};
 use rustc_target::abi::Align;
 
 use crate::builder::Builder;
+use crate::errors::{
+    InvalidMonomorphizationInvalidFloatVector,
+    InvalidMonomorphizationNotFloat,
+    InvalidMonomorphizationUnrecognized,
+    InvalidMonomorphizationExpectedSignedUnsigned,
+    InvalidMonomorphizationUnsupportedElement,
+    InvalidMonomorphizationInvalidBitmask,
+    InvalidMonomorphizationSimdShuffle,
+    InvalidMonomorphizationExpectedSimd,
+    InvalidMonomorphizationMaskType,
+    InvalidMonomorphizationReturnLength,
+    InvalidMonomorphizationReturnLengthInputType,
+    InvalidMonomorphizationReturnElement,
+    InvalidMonomorphizationReturnType,
+    InvalidMonomorphizationInsertedType,
+    InvalidMonomorphizationReturnIntegerType,
+    InvalidMonomorphizationMismatchedLengths,
+    InvalidMonomorphizationUnsupportedCast,
+    InvalidMonomorphizationUnsupportedOperation
+};
 use crate::intrinsic;
 
 pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>, name: Symbol, callee_ty: Ty<'tcx>, args: &[OperandRef<'tcx, RValue<'gcc>>], ret_ty: Ty<'tcx>, llret_ty: Type<'gcc>, span: Span) -> Result<RValue<'gcc>, ()> {
     // macros for error handling:
-    #[allow(unused_macro_rules)]
-    macro_rules! emit_error {
-        ($msg: tt) => {
-            emit_error!($msg, )
-        };
-        ($msg: tt, $($fmt: tt)*) => {
-            span_invalid_monomorphization_error(
-                bx.sess(), span,
-                &format!(concat!("invalid monomorphization of `{}` intrinsic: ", $msg),
-                         name, $($fmt)*));
-        }
-    }
-
     macro_rules! return_error {
-        ($($fmt: tt)*) => {
+        ($err:expr) => {
             {
-                emit_error!($($fmt)*);
+                bx.sess().emit_err($err);
                 return Err(());
             }
         }
     }
-
     macro_rules! require {
-        ($cond: expr, $($fmt: tt)*) => {
+        ($cond:expr, $err:expr) => {
             if !$cond {
-                return_error!($($fmt)*);
+                return_error!($err);
             }
-        };
+        }
     }
-
     macro_rules! require_simd {
         ($ty: expr, $position: expr) => {
-            require!($ty.is_simd(), "expected SIMD {} type, found non-SIMD `{}`", $position, $ty)
+            require!($ty.is_simd(), InvalidMonomorphizationExpectedSimd { span, name, position: $position, found_ty: $ty })
         };
     }
 
@@ -82,10 +87,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                 bx.load(int_ty, ptr, Align::ONE)
             }
             _ => return_error!(
-                "invalid bitmask `{}`, expected `u{}` or `[u8; {}]`",
-                mask_ty,
-                expected_int_bits,
-                expected_bytes
+                InvalidMonomorphizationInvalidBitmask { span, name, ty: mask_ty, expected_int_bits, expected_bytes }
             ),
         };
 
@@ -127,18 +129,11 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
         let (out_len, out_ty) = ret_ty.simd_size_and_type(bx.tcx());
         require!(
             in_len == out_len,
-            "expected return type with length {} (same as input type `{}`), \
-             found `{}` with length {}",
-            in_len,
-            in_ty,
-            ret_ty,
-            out_len
+            InvalidMonomorphizationReturnLengthInputType { span, name, in_len, in_ty, ret_ty, out_len }
         );
         require!(
             bx.type_kind(bx.element_type(llret_ty)) == TypeKind::Integer,
-            "expected return type with integer elements, found `{}` with non-integer `{}`",
-            ret_ty,
-            out_ty
+            InvalidMonomorphizationReturnIntegerType {span, name, ret_ty, out_ty}
         );
 
         return Ok(compare_simd_types(
@@ -163,8 +158,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                         })
                     }
                     _ => return_error!(
-                        "simd_shuffle index must be an array of `u32`, got `{}`",
-                        args[2].layout.ty
+                        InvalidMonomorphizationSimdShuffle { span, name, ty: args[2].layout.ty }
                     ),
                 }
             }
@@ -179,19 +173,11 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
         let (out_len, out_ty) = ret_ty.simd_size_and_type(bx.tcx());
         require!(
             out_len == n,
-            "expected return type of length {}, found `{}` with length {}",
-            n,
-            ret_ty,
-            out_len
+            InvalidMonomorphizationReturnLength { span, name, in_len: n, ret_ty, out_len }
         );
         require!(
             in_elem == out_ty,
-            "expected return element type `{}` (element of input `{}`), \
-             found `{}` with element type `{}`",
-            in_elem,
-            in_ty,
-            ret_ty,
-            out_ty
+            InvalidMonomorphizationReturnElement { span, name, in_elem, in_ty, ret_ty, out_ty }
         );
 
         let vector = args[2].immediate();
@@ -207,10 +193,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
     if name == sym::simd_insert {
         require!(
             in_elem == arg_tys[2],
-            "expected inserted type `{}` (element of input `{}`), found `{}`",
-            in_elem,
-            in_ty,
-            arg_tys[2]
+            InvalidMonomorphizationInsertedType { span, name, in_elem, in_ty, out_ty: arg_tys[2] }
         );
         let vector = args[0].immediate();
         let index = args[1].immediate();
@@ -263,10 +246,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
     if name == sym::simd_extract {
         require!(
             ret_ty == in_elem,
-            "expected return type `{}` (element of input `{}`), found `{}`",
-            in_elem,
-            in_ty,
-            ret_ty
+            InvalidMonomorphizationReturnType { span, name, in_elem, in_ty, ret_ty }
         );
         let vector = args[0].immediate();
         return Ok(bx.context.new_vector_access(None, vector, args[1].immediate()).to_rvalue());
@@ -279,13 +259,11 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
         let (v_len, _) = arg_tys[1].simd_size_and_type(bx.tcx());
         require!(
             m_len == v_len,
-            "mismatched lengths: mask length `{}` != other vector length `{}`",
-            m_len,
-            v_len
+            InvalidMonomorphizationMismatchedLengths { span, name, m_len, v_len }
         );
         match m_elem_ty.kind() {
             ty::Int(_) => {}
-            _ => return_error!("mask element type is `{}`, expected `i_`", m_elem_ty),
+            _ => return_error!(InvalidMonomorphizationMaskType { span, name, ty: m_elem_ty }),
         }
         return Ok(bx.vector_select(args[0].immediate(), args[1].immediate(), args[2].immediate()));
     }
@@ -295,12 +273,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
         let (out_len, out_elem) = ret_ty.simd_size_and_type(bx.tcx());
         require!(
             in_len == out_len,
-            "expected return type with length {} (same as input type `{}`), \
-                  found `{}` with length {}",
-            in_len,
-            in_ty,
-            ret_ty,
-            out_len
+            InvalidMonomorphizationReturnLengthInputType { span, name, in_len, in_ty, ret_ty, out_len }
         );
         // casting cares about nominal type, not just structural type
         if in_elem == out_elem {
@@ -412,13 +385,8 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
             }
             _ => { /* Unsupported. Fallthrough. */ }
         }
-        require!(
-            false,
-            "unsupported cast from `{}` with element `{}` to `{}` with element `{}`",
-            in_ty,
-            in_elem,
-            ret_ty,
-            out_elem
+        return_error!(
+            InvalidMonomorphizationUnsupportedCast { span, name, in_ty, in_elem, ret_ty, out_elem }
         );
     }
 
@@ -431,10 +399,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                     })*
                     _ => {},
                 }
-                require!(false,
-                         "unsupported operation on `{}` with element `{}`",
-                         in_ty,
-                         in_elem)
+                return_error!(InvalidMonomorphizationUnsupportedOperation { span, name, in_ty, in_elem })
             })*
         }
     }
@@ -448,23 +413,14 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
         span: Span,
         args: &[OperandRef<'tcx, RValue<'gcc>>],
     ) -> Result<RValue<'gcc>, ()> {
-        macro_rules! emit_error {
-            ($msg: tt, $($fmt: tt)*) => {
-                span_invalid_monomorphization_error(
-                    bx.sess(), span,
-                    &format!(concat!("invalid monomorphization of `{}` intrinsic: ", $msg),
-                             name, $($fmt)*));
-            }
-        }
         macro_rules! return_error {
-            ($($fmt: tt)*) => {
+            ($err:expr) => {
                 {
-                    emit_error!($($fmt)*);
+                    bx.sess().emit_err($err);
                     return Err(());
                 }
             }
         }
-
         let (elem_ty_str, elem_ty) =
             if let ty::Float(f) = in_elem.kind() {
                 let elem_ty = bx.cx.type_float_from_ty(*f);
@@ -472,16 +428,12 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                     32 => ("f32", elem_ty),
                     64 => ("f64", elem_ty),
                     _ => {
-                        return_error!(
-                            "unsupported element type `{}` of floating-point vector `{}`",
-                            f.name_str(),
-                            in_ty
-                        );
+                        return_error!(InvalidMonomorphizationInvalidFloatVector { span, name, elem_ty: f.name_str(), vec_ty: in_ty });
                     }
                 }
             }
             else {
-                return_error!("`{}` is not a floating-point type", in_ty);
+                return_error!(InvalidMonomorphizationNotFloat { span, name, ty: in_ty });
             };
 
         let vec_ty = bx.cx.type_vector(elem_ty, in_len);
@@ -504,7 +456,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                 sym::simd_fsqrt => ("sqrt", bx.type_func(&[vec_ty], vec_ty)),
                 sym::simd_round => ("round", bx.type_func(&[vec_ty], vec_ty)),
                 sym::simd_trunc => ("trunc", bx.type_func(&[vec_ty], vec_ty)),
-                _ => return_error!("unrecognized intrinsic `{}`", name),
+                _ => return_error!(InvalidMonomorphizationUnrecognized { span, name })
             };
         let llvm_name = &format!("llvm.{0}.v{1}{2}", intr_name, in_len, elem_ty_str);
         let function = intrinsic::llvm::intrinsic(llvm_name, &bx.cx);
@@ -557,10 +509,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                     })*
                     _ => {},
                 }
-                require!(false,
-                         "unsupported operation on `{}` with element `{}`",
-                         in_ty,
-                         in_elem)
+                return_error!(InvalidMonomorphizationUnsupportedOperation { span, name, in_ty, in_elem })
             })*
         }
     }
@@ -579,12 +528,12 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
             ty::Int(i) => (true, i.bit_width().unwrap_or(ptr_bits), bx.cx.type_int_from_ty(i)),
             ty::Uint(i) => (false, i.bit_width().unwrap_or(ptr_bits), bx.cx.type_uint_from_ty(i)),
             _ => {
-                return_error!(
-                    "expected element type `{}` of vector type `{}` \
-                     to be a signed or unsigned integer type",
-                    arg_tys[0].simd_size_and_type(bx.tcx()).1,
-                    arg_tys[0]
-                );
+                return_error!(InvalidMonomorphizationExpectedSignedUnsigned {
+                    span,
+                    name,
+                    elem_ty: arg_tys[0].simd_size_and_type(bx.tcx()).1,
+                    vec_ty: arg_tys[0],
+                });
             }
         };
         let builtin_name =
@@ -617,10 +566,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
             if name == sym::$name {
                 require!(
                     ret_ty == in_elem,
-                    "expected return type `{}` (element of input `{}`), found `{}`",
-                    in_elem,
-                    in_ty,
-                    ret_ty
+                    InvalidMonomorphizationReturnType { span, name, in_elem, in_ty, ret_ty }
                 );
                 return match in_elem.kind() {
                     ty::Int(_) | ty::Uint(_) => {
@@ -644,13 +590,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                             Ok(bx.vector_reduce_op(args[0].immediate(), $vec_op))
                         }
                     }
-                    _ => return_error!(
-                        "unsupported {} from `{}` with element `{}` to `{}`",
-                        sym::$name,
-                        in_ty,
-                        in_elem,
-                        ret_ty
-                    ),
+                    _ => return_error!(InvalidMonomorphizationUnsupportedElement { span, name, in_ty, elem_ty: in_elem, ret_ty }),
                 };
             }
         };
@@ -676,20 +616,11 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
             if name == sym::$name {
                 require!(
                     ret_ty == in_elem,
-                    "expected return type `{}` (element of input `{}`), found `{}`",
-                    in_elem,
-                    in_ty,
-                    ret_ty
+                    InvalidMonomorphizationReturnType { span, name, in_elem, in_ty, ret_ty }
                 );
                 return match in_elem.kind() {
                     ty::Int(_) | ty::Uint(_) | ty::Float(_) => Ok(bx.$reduction(args[0].immediate())),
-                    _ => return_error!(
-                        "unsupported {} from `{}` with element `{}` to `{}`",
-                        sym::$name,
-                        in_ty,
-                        in_elem,
-                        ret_ty
-                    ),
+                    _ => return_error!(InvalidMonomorphizationUnsupportedElement { span, name, in_ty, elem_ty: in_elem, ret_ty }),
                 };
             }
         };
@@ -704,22 +635,13 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                 let input = if !$boolean {
                     require!(
                         ret_ty == in_elem,
-                        "expected return type `{}` (element of input `{}`), found `{}`",
-                        in_elem,
-                        in_ty,
-                        ret_ty
+                        InvalidMonomorphizationReturnType { span, name, in_elem, in_ty, ret_ty }
                     );
                     args[0].immediate()
                 } else {
                     match in_elem.kind() {
                         ty::Int(_) | ty::Uint(_) => {}
-                        _ => return_error!(
-                            "unsupported {} from `{}` with element `{}` to `{}`",
-                            sym::$name,
-                            in_ty,
-                            in_elem,
-                            ret_ty
-                        ),
+                        _ => return_error!(InvalidMonomorphizationUnsupportedElement { span, name, in_ty, elem_ty: in_elem, ret_ty }),
                     }
 
                     // boolean reductions operate on vectors of i1s:
@@ -733,11 +655,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
                         Ok(if !$boolean { r } else { bx.zext(r, bx.type_bool()) })
                     }
                     _ => return_error!(
-                        "unsupported {} from `{}` with element `{}` to `{}`",
-                        sym::$name,
-                        in_ty,
-                        in_elem,
-                        ret_ty
+                        InvalidMonomorphizationUnsupportedElement { span, name, in_ty, elem_ty: in_elem, ret_ty }
                     ),
                 };
             }
diff --git a/compiler/rustc_codegen_gcc/src/lib.rs b/compiler/rustc_codegen_gcc/src/lib.rs
index 223466fb9b5..007d61ed51d 100644
--- a/compiler/rustc_codegen_gcc/src/lib.rs
+++ b/compiler/rustc_codegen_gcc/src/lib.rs
@@ -18,6 +18,8 @@
 #![recursion_limit="256"]
 #![warn(rust_2018_idioms)]
 #![warn(unused_lifetimes)]
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 
 extern crate rustc_apfloat;
 extern crate rustc_ast;
@@ -25,6 +27,7 @@ extern crate rustc_codegen_ssa;
 extern crate rustc_data_structures;
 extern crate rustc_errors;
 extern crate rustc_hir;
+extern crate rustc_macros;
 extern crate rustc_metadata;
 extern crate rustc_middle;
 extern crate rustc_session;
@@ -50,6 +53,7 @@ mod context;
 mod coverageinfo;
 mod debuginfo;
 mod declare;
+mod errors;
 mod int;
 mod intrinsic;
 mod mono_item;
@@ -59,6 +63,7 @@ mod type_of;
 use std::any::Any;
 use std::sync::{Arc, Mutex};
 
+use crate::errors::LTONotSupported;
 use gccjit::{Context, OptimizationLevel, CType};
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen};
@@ -97,7 +102,7 @@ pub struct GccCodegenBackend {
 impl CodegenBackend for GccCodegenBackend {
     fn init(&self, sess: &Session) {
         if sess.lto() != Lto::No {
-            sess.warn("LTO is not supported. You may get a linker error.");
+            sess.emit_warning(LTONotSupported {});
         }
 
         let temp_dir = TempDir::new().expect("cannot create temporary directory");