Rollup merge of #149781 - mu001999-contrib:fix/149756, r=jdonszelmann

Don't suggest wrapping attr in unsafe if it may come from proc macro

Don't emit the suggestion if the span may come from proc macro. Check this with the snippet because we cannot check if the span is from macro-rules or proc-macro (maybe this can happen in the future?).

Fixes #149756

Author: matthiaskrgr

compiler/rustc_attr_parsing/src/safety.rs

@@ -62,16 +62,28 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
                     Some(unsafe_since) => path_span.edition() >= unsafe_since,
                 };
 
+                let mut not_from_proc_macro = true;
+                if diag_span.from_expansion()
+                    && let Ok(mut snippet) = self.sess.source_map().span_to_snippet(diag_span)
+                {
+                    snippet.retain(|c| !c.is_whitespace());
+                    if snippet.contains("!(") || snippet.starts_with("#[") && snippet.ends_with("]")
+                    {
+                        not_from_proc_macro = false;
+                    }
+                }
+
                 if emit_error {
                     self.stage.emit_err(
                         self.sess,
                         crate::session_diagnostics::UnsafeAttrOutsideUnsafe {
                             span: path_span,
-                            suggestion:
+                            suggestion: not_from_proc_macro.then(|| {
                                 crate::session_diagnostics::UnsafeAttrOutsideUnsafeSuggestion {
                                     left: diag_span.shrink_to_lo(),
                                     right: diag_span.shrink_to_hi(),
-                                },
+                                }
+                            }),
                         },
                     );
                 } else {
@@ -81,7 +93,8 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
                         span: path_span,
                         kind: AttributeLintKind::UnsafeAttrOutsideUnsafe {
                             attribute_name_span: path_span,
-                            sugg_spans: (diag_span.shrink_to_lo(), diag_span.shrink_to_hi()),
+                            sugg_spans: not_from_proc_macro
+                                .then(|| (diag_span.shrink_to_lo(), diag_span.shrink_to_hi())),
                         },
                     })
                 }

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -758,7 +758,7 @@ pub(crate) struct UnsafeAttrOutsideUnsafe {
     #[label]
     pub span: Span,
     #[subdiagnostic]
-    pub suggestion: UnsafeAttrOutsideUnsafeSuggestion,
+    pub suggestion: Option<UnsafeAttrOutsideUnsafeSuggestion>,
 }
 
 #[derive(Subdiagnostic)]

compiler/rustc_lint/src/early/diagnostics.rs

@@ -353,14 +353,14 @@ pub fn decorate_attribute_lint(
             }
             .decorate_lint(diag)
         }
-        &AttributeLintKind::UnsafeAttrOutsideUnsafe {
-            attribute_name_span,
-            sugg_spans: (left, right),
-        } => lints::UnsafeAttrOutsideUnsafeLint {
-            span: attribute_name_span,
-            suggestion: lints::UnsafeAttrOutsideUnsafeSuggestion { left, right },
+        &AttributeLintKind::UnsafeAttrOutsideUnsafe { attribute_name_span, sugg_spans } => {
+            lints::UnsafeAttrOutsideUnsafeLint {
+                span: attribute_name_span,
+                suggestion: sugg_spans
+                    .map(|(left, right)| lints::UnsafeAttrOutsideUnsafeSuggestion { left, right }),
+            }
+            .decorate_lint(diag)
         }
-        .decorate_lint(diag),
         &AttributeLintKind::UnexpectedCfgName(name, value) => {
             check_cfg::unexpected_cfg_name(sess, tcx, name, value).decorate_lint(diag)
         }

compiler/rustc_lint/src/lints.rs

@@ -3177,7 +3177,7 @@ pub(crate) struct UnsafeAttrOutsideUnsafeLint {
     #[label]
     pub span: Span,
     #[subdiagnostic]
-    pub suggestion: UnsafeAttrOutsideUnsafeSuggestion,
+    pub suggestion: Option<UnsafeAttrOutsideUnsafeSuggestion>,
 }
 
 #[derive(Subdiagnostic)]

compiler/rustc_lint_defs/src/lib.rs

@@ -729,7 +729,7 @@ pub enum AttributeLintKind {
     },
     UnsafeAttrOutsideUnsafe {
         attribute_name_span: Span,
-        sugg_spans: (Span, Span),
+        sugg_spans: Option<(Span, Span)>,
     },
     UnexpectedCfgName((Symbol, Span), Option<(Symbol, Span)>),
     UnexpectedCfgValue((Symbol, Span), Option<(Symbol, Span)>),

tests/ui/rust-2024/unsafe-attributes/auxiliary/unsafe-attributes-pm-in-2024.rs

@@ -0,0 +1,29 @@
+//@ edition: 2024
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn missing_unsafe(_input: TokenStream) -> TokenStream {
+    "#[no_mangle] pub fn abc() {}".parse().unwrap()
+}
+
+#[proc_macro_attribute]
+pub fn attr_missing_unsafe(_attr: TokenStream, _input: TokenStream) -> TokenStream {
+    "#[no_mangle] pub fn bar() {}".parse().unwrap()
+}
+
+#[proc_macro_derive(AttrMissingUnsafe)]
+pub fn derive_attr_missing_unsafe(_input: TokenStream) -> TokenStream {
+    "#[no_mangle] pub fn baz() {}".parse().unwrap()
+}
+
+#[proc_macro]
+pub fn macro_rules_missing_unsafe(_input: TokenStream) -> TokenStream {
+    "macro_rules! make_fn {
+        () => { #[no_mangle] pub fn foo() { } };
+    }"
+    .parse()
+    .unwrap()
+}

tests/ui/rust-2024/unsafe-attributes/unsafe-attributes-from-pm-in-2024.rs

@@ -0,0 +1,18 @@
+// Test for unsafe attributes generated by a proc-macro.
+
+//@ proc-macro: unsafe-attributes-pm-in-2024.rs
+//@ ignore-backends: gcc
+
+unsafe_attributes_pm_in_2024::missing_unsafe!(); //~ ERROR unsafe attribute used without unsafe
+
+#[unsafe_attributes_pm_in_2024::attr_missing_unsafe] //~ ERROR unsafe attribute used without unsafe
+pub fn bar() {}
+
+#[derive(unsafe_attributes_pm_in_2024::AttrMissingUnsafe)] //~ ERROR unsafe attribute used without unsafe
+struct Baz;
+
+unsafe_attributes_pm_in_2024::macro_rules_missing_unsafe!(); //~ ERROR unsafe attribute used without unsafe
+
+make_fn!();
+
+fn main() {}

tests/ui/rust-2024/unsafe-attributes/unsafe-attributes-from-pm-in-2024.stderr

@@ -0,0 +1,37 @@
+error: unsafe attribute used without unsafe
+  --> $DIR/unsafe-attributes-from-pm-in-2024.rs:6:1
+   |
+LL | unsafe_attributes_pm_in_2024::missing_unsafe!();
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ usage of unsafe attribute
+   |
+   = note: this error originates in the macro `unsafe_attributes_pm_in_2024::missing_unsafe` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: unsafe attribute used without unsafe
+  --> $DIR/unsafe-attributes-from-pm-in-2024.rs:8:1
+   |
+LL | #[unsafe_attributes_pm_in_2024::attr_missing_unsafe]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ usage of unsafe attribute
+   |
+   = note: this error originates in the attribute macro `unsafe_attributes_pm_in_2024::attr_missing_unsafe` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: unsafe attribute used without unsafe
+  --> $DIR/unsafe-attributes-from-pm-in-2024.rs:11:10
+   |
+LL | #[derive(unsafe_attributes_pm_in_2024::AttrMissingUnsafe)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ usage of unsafe attribute
+   |
+   = note: this error originates in the derive macro `unsafe_attributes_pm_in_2024::AttrMissingUnsafe` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: unsafe attribute used without unsafe
+  --> $DIR/unsafe-attributes-from-pm-in-2024.rs:14:1
+   |
+LL | unsafe_attributes_pm_in_2024::macro_rules_missing_unsafe!();
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ usage of unsafe attribute
+LL |
+LL | make_fn!();
+   | ---------- in this macro invocation
+   |
+   = note: this error originates in the macro `make_fn` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 4 previous errors
+