Rollup merge of #85627 - LeSeulArtichaut:thir-unsafe-fn-lint, r=nikomatsakis

Fix a few details in THIR unsafeck

This makes it consistent with RFC 2585 (`unsafe_op_in_unsafe_fn`) and with the MIR unsafeck.

r? `@nikomatsakis`

4 files changed, 166 insertions, 32 deletions

diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index 7e64c5f189e..971b6dd9e1c 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -42,7 +42,7 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
             self.warn_unused_unsafe(
                 hir_id,
                 block_span,
-                Some(self.tcx.sess.source_map().guess_head_span(enclosing_span)),
+                Some((self.tcx.sess.source_map().guess_head_span(enclosing_span), "block")),
             );
             f(self);
         } else {
@@ -52,7 +52,15 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
             f(self);
 
             if let SafetyContext::UnsafeBlock { used: false, span, hir_id } = self.safety_context {
-                self.warn_unused_unsafe(hir_id, span, self.body_unsafety.unsafe_fn_sig_span());
+                self.warn_unused_unsafe(
+                    hir_id,
+                    span,
+                    if self.unsafe_op_in_unsafe_fn_allowed() {
+                        self.body_unsafety.unsafe_fn_sig_span().map(|span| (span, "fn"))
+                    } else {
+                        None
+                    },
+                );
             }
             self.safety_context = prev_context;
             return;
@@ -72,16 +80,20 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
             SafetyContext::UnsafeFn if unsafe_op_in_unsafe_fn_allowed => {}
             SafetyContext::UnsafeFn => {
                 // unsafe_op_in_unsafe_fn is disallowed
-                struct_span_err!(
-                    self.tcx.sess,
+                self.tcx.struct_span_lint_hir(
+                    UNSAFE_OP_IN_UNSAFE_FN,
+                    self.hir_context,
                     span,
-                    E0133,
-                    "{} is unsafe and requires unsafe block",
-                    description,
+                    |lint| {
+                        lint.build(&format!(
+                            "{} is unsafe and requires unsafe block (error E0133)",
+                            description,
+                        ))
+                        .span_label(span, description)
+                        .note(note)
+                        .emit();
+                    },
                 )
-                .span_label(span, description)
-                .note(note)
-                .emit();
             }
             SafetyContext::Safe => {
                 let fn_sugg = if unsafe_op_in_unsafe_fn_allowed { " function or" } else { "" };
@@ -104,18 +116,15 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
         &self,
         hir_id: hir::HirId,
         block_span: Span,
-        enclosing_span: Option<Span>,
+        enclosing_unsafe: Option<(Span, &'static str)>,
     ) {
         let block_span = self.tcx.sess.source_map().guess_head_span(block_span);
         self.tcx.struct_span_lint_hir(UNUSED_UNSAFE, hir_id, block_span, |lint| {
             let msg = "unnecessary `unsafe` block";
             let mut db = lint.build(msg);
             db.span_label(block_span, msg);
-            if let Some(enclosing_span) = enclosing_span {
-                db.span_label(
-                    enclosing_span,
-                    format!("because it's nested under this `unsafe` block"),
-                );
+            if let Some((span, kind)) = enclosing_unsafe {
+                db.span_label(span, format!("because it's nested under this `unsafe` {}", kind));
             }
             db.emit();
         });
diff --git a/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.stderr b/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.mir.stderr
index ad93267ca01..9a522fac65f 100644
--- a/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.stderr
+++ b/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.mir.stderr
@@ -1,18 +1,18 @@
 error: call to unsafe function is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:9:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:12:5
    |
 LL |     unsf();
    |     ^^^^^^ call to unsafe function
    |
 note: the lint level is defined here
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:1:9
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:4:9
    |
 LL | #![deny(unsafe_op_in_unsafe_fn)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
    = note: consult the function's documentation for information on how to avoid undefined behavior
 
 error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:11:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:14:5
    |
 LL |     *PTR;
    |     ^^^^ dereference of raw pointer
@@ -20,7 +20,7 @@ LL |     *PTR;
    = note: raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
 
 error: use of mutable static is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:13:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:16:5
    |
 LL |     VOID = ();
    |     ^^^^^^^^^ use of mutable static
@@ -28,25 +28,25 @@ LL |     VOID = ();
    = note: mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
 
 error: unnecessary `unsafe` block
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:16:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:19:5
    |
 LL |     unsafe {}
    |     ^^^^^^ unnecessary `unsafe` block
    |
 note: the lint level is defined here
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:2:9
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:5:9
    |
 LL | #![deny(unused_unsafe)]
    |         ^^^^^^^^^^^^^
 
 error: call to unsafe function is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:24:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:27:5
    |
 LL |     unsf();
    |     ^^^^^^ call to unsafe function
    |
 note: the lint level is defined here
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:22:8
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:25:8
    |
 LL | #[deny(warnings)]
    |        ^^^^^^^^
@@ -54,7 +54,7 @@ LL | #[deny(warnings)]
    = note: consult the function's documentation for information on how to avoid undefined behavior
 
 error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:26:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:29:5
    |
 LL |     *PTR;
    |     ^^^^ dereference of raw pointer
@@ -62,7 +62,7 @@ LL |     *PTR;
    = note: raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
 
 error: use of mutable static is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:28:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:31:5
    |
 LL |     VOID = ();
    |     ^^^^^^^^^ use of mutable static
@@ -70,13 +70,13 @@ LL |     VOID = ();
    = note: mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
 
 error: unnecessary `unsafe` block
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:30:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:33:5
    |
 LL |     unsafe {}
    |     ^^^^^^ unnecessary `unsafe` block
 
 error: unnecessary `unsafe` block
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:44:14
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:47:14
    |
 LL |     unsafe { unsafe { unsf() } }
    |     ------   ^^^^^^ unnecessary `unsafe` block
@@ -84,7 +84,7 @@ LL |     unsafe { unsafe { unsf() } }
    |     because it's nested under this `unsafe` block
 
 error: unnecessary `unsafe` block
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:55:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:58:5
    |
 LL | unsafe fn allow_level() {
    | ----------------------- because it's nested under this `unsafe` fn
@@ -93,7 +93,7 @@ LL |     unsafe { unsf() }
    |     ^^^^^^ unnecessary `unsafe` block
 
 error: unnecessary `unsafe` block
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:67:9
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:70:9
    |
 LL | unsafe fn nested_allow_level() {
    | ------------------------------ because it's nested under this `unsafe` fn
@@ -102,7 +102,7 @@ LL |         unsafe { unsf() }
    |         ^^^^^^ unnecessary `unsafe` block
 
 error[E0133]: call to unsafe function is unsafe and requires unsafe block
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:73:5
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:76:5
    |
 LL |     unsf();
    |     ^^^^^^ call to unsafe function
@@ -110,7 +110,7 @@ LL |     unsf();
    = note: consult the function's documentation for information on how to avoid undefined behavior
 
 error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
-  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:77:9
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:80:9
    |
 LL |         unsf();
    |         ^^^^^^ call to unsafe function
diff --git a/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.rs b/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.rs
index c8400a6fc4d..7ca714b85c2 100644
--- a/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.rs
+++ b/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.rs
@@ -1,3 +1,6 @@
+// revisions: mir thir
+// [thir]compile-flags: -Zthir-unsafeck
+
 #![deny(unsafe_op_in_unsafe_fn)]
 #![deny(unused_unsafe)]
 
diff --git a/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.thir.stderr b/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.thir.stderr
new file mode 100644
index 00000000000..ad87690bb52
--- /dev/null
+++ b/src/test/ui/unsafe/rfc-2585-unsafe_op_in_unsafe_fn.thir.stderr
@@ -0,0 +1,122 @@
+error: call to unsafe function is unsafe and requires unsafe block (error E0133)
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:12:5
+   |
+LL |     unsf();
+   |     ^^^^^^ call to unsafe function
+   |
+note: the lint level is defined here
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:4:9
+   |
+LL | #![deny(unsafe_op_in_unsafe_fn)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:14:5
+   |
+LL |     *PTR;
+   |     ^^^^ dereference of raw pointer
+   |
+   = note: raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
+
+error: use of mutable static is unsafe and requires unsafe block (error E0133)
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:16:5
+   |
+LL |     VOID = ();
+   |     ^^^^ use of mutable static
+   |
+   = note: mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+
+error: unnecessary `unsafe` block
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:19:5
+   |
+LL |     unsafe {}
+   |     ^^^^^^ unnecessary `unsafe` block
+   |
+note: the lint level is defined here
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:5:9
+   |
+LL | #![deny(unused_unsafe)]
+   |         ^^^^^^^^^^^^^
+
+error: call to unsafe function is unsafe and requires unsafe block (error E0133)
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:27:5
+   |
+LL |     unsf();
+   |     ^^^^^^ call to unsafe function
+   |
+note: the lint level is defined here
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:25:8
+   |
+LL | #[deny(warnings)]
+   |        ^^^^^^^^
+   = note: `#[deny(unsafe_op_in_unsafe_fn)]` implied by `#[deny(warnings)]`
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: dereference of raw pointer is unsafe and requires unsafe block (error E0133)
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:29:5
+   |
+LL |     *PTR;
+   |     ^^^^ dereference of raw pointer
+   |
+   = note: raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
+
+error: use of mutable static is unsafe and requires unsafe block (error E0133)
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:31:5
+   |
+LL |     VOID = ();
+   |     ^^^^ use of mutable static
+   |
+   = note: mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+
+error: unnecessary `unsafe` block
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:33:5
+   |
+LL |     unsafe {}
+   |     ^^^^^^ unnecessary `unsafe` block
+
+error: unnecessary `unsafe` block
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:47:14
+   |
+LL |     unsafe { unsafe { unsf() } }
+   |     ------   ^^^^^^ unnecessary `unsafe` block
+   |     |
+   |     because it's nested under this `unsafe` block
+
+error: unnecessary `unsafe` block
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:58:5
+   |
+LL | unsafe fn allow_level() {
+   | ----------------------- because it's nested under this `unsafe` fn
+...
+LL |     unsafe { unsf() }
+   |     ^^^^^^ unnecessary `unsafe` block
+
+error: unnecessary `unsafe` block
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:70:9
+   |
+LL | unsafe fn nested_allow_level() {
+   | ------------------------------ because it's nested under this `unsafe` fn
+...
+LL |         unsafe { unsf() }
+   |         ^^^^^^ unnecessary `unsafe` block
+
+error[E0133]: call to unsafe function is unsafe and requires unsafe block
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:76:5
+   |
+LL |     unsf();
+   |     ^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
+  --> $DIR/rfc-2585-unsafe_op_in_unsafe_fn.rs:80:9
+   |
+LL |         unsf();
+   |         ^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: aborting due to 13 previous errors
+
+For more information about this error, try `rustc --explain E0133`.