Auto merge of #93678 - steffahn:better_unsafe_diagnostics, r=nagisa

Improve `unused_unsafe` lint

I’m going to add some motivation and explanation below, particularly pointing the changes in behavior from this PR.

_Edit:_ Looking for existing issues, looks like this PR fixes #88260.

_Edit2:_ Now also contains code that closes #90776.

compiler/rustc_codegen_llvm/src/abi.rs

@@ -599,13 +599,11 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
         if self.conv == Conv::CCmseNonSecureCall {
             // This will probably get ignored on all targets but those supporting the TrustZone-M
             // extension (thumbv8m targets).
-            unsafe {
-                llvm::AddCallSiteAttrString(
-                    callsite,
-                    llvm::AttributePlace::Function,
-                    cstr::cstr!("cmse_nonsecure_call"),
-                );
-            }
+            llvm::AddCallSiteAttrString(
+                callsite,
+                llvm::AttributePlace::Function,
+                cstr::cstr!("cmse_nonsecure_call"),
+            );
         }
     }
 }