add diagnostic for raw identifiers in format string

3 files changed, 50 insertions, 28 deletions

diff --git a/compiler/rustc_builtin_macros/messages.ftl b/compiler/rustc_builtin_macros/messages.ftl
index 8d8db4c13fa..207ae8ad844 100644
--- a/compiler/rustc_builtin_macros/messages.ftl
+++ b/compiler/rustc_builtin_macros/messages.ftl
@@ -137,6 +137,8 @@ builtin_macros_format_positional_after_named = positional arguments cannot follo
     .label = positional arguments must be before named arguments
     .named_args = named argument
 
+builtin_macros_format_remove_raw_ident = remove the `r#`
+
 builtin_macros_format_requires_string = requires at least a format string argument
 
 builtin_macros_format_string_invalid = invalid format string: {$desc}
@@ -165,6 +167,8 @@ builtin_macros_format_unused_arg = {$named ->
 builtin_macros_format_unused_args = multiple unused formatting arguments
     .label = multiple missing formatting specifiers
 
+builtin_macros_format_use_positional = consider using a positional formatting argument instead
+
 builtin_macros_global_asm_clobber_abi = `clobber_abi` cannot be used with `global_asm!`
 
 builtin_macros_invalid_crate_attribute = invalid crate attribute
@@ -205,8 +209,6 @@ builtin_macros_requires_cfg_pattern =
 
 builtin_macros_should_panic = functions using `#[should_panic]` must return `()`
 
-builtin_macros_sugg = consider using a positional formatting argument instead
-
 builtin_macros_test_arg_non_lifetime = functions used as tests can not have any non-lifetime generic parameters
 
 builtin_macros_test_args = functions used as tests can not have any arguments
diff --git a/compiler/rustc_builtin_macros/src/errors.rs b/compiler/rustc_builtin_macros/src/errors.rs
index fbf0395bb05..1238773d58b 100644
--- a/compiler/rustc_builtin_macros/src/errors.rs
+++ b/compiler/rustc_builtin_macros/src/errors.rs
@@ -539,18 +539,29 @@ pub(crate) struct InvalidFormatStringLabel {
 }
 
 #[derive(Subdiagnostic)]
-#[multipart_suggestion(
-    builtin_macros_sugg,
-    style = "verbose",
-    applicability = "machine-applicable"
-)]
-pub(crate) struct InvalidFormatStringSuggestion {
-    #[suggestion_part(code = "{len}")]
-    pub(crate) captured: Span,
-    pub(crate) len: String,
-    #[suggestion_part(code = ", {arg}")]
-    pub(crate) span: Span,
-    pub(crate) arg: String,
+pub(crate) enum InvalidFormatStringSuggestion {
+    #[multipart_suggestion(
+        builtin_macros_format_use_positional,
+        style = "verbose",
+        applicability = "machine-applicable"
+    )]
+    UsePositional {
+        #[suggestion_part(code = "{len}")]
+        captured: Span,
+        len: String,
+        #[suggestion_part(code = ", {arg}")]
+        span: Span,
+        arg: String,
+    },
+    #[suggestion(
+        builtin_macros_format_remove_raw_ident,
+        code = "",
+        applicability = "machine-applicable"
+    )]
+    RemoveRawIdent {
+        #[primary_span]
+        span: Span,
+    },
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_builtin_macros/src/format.rs b/compiler/rustc_builtin_macros/src/format.rs
index ede95dbf897..8397b5e4221 100644
--- a/compiler/rustc_builtin_macros/src/format.rs
+++ b/compiler/rustc_builtin_macros/src/format.rs
@@ -260,20 +260,29 @@ fn make_format_args(
         if let Some((label, span)) = err.secondary_label && is_source_literal {
             e.label_ = Some(errors::InvalidFormatStringLabel { span: fmt_span.from_inner(InnerSpan::new(span.start, span.end)), label } );
         }
-        if err.should_be_replaced_with_positional_argument {
-            let captured_arg_span =
-                fmt_span.from_inner(InnerSpan::new(err.span.start, err.span.end));
-            if let Ok(arg) = ecx.source_map().span_to_snippet(captured_arg_span) {
-                let span = match args.unnamed_args().last() {
-                    Some(arg) => arg.expr.span,
-                    None => fmt_span,
-                };
-                e.sugg_ = Some(errors::InvalidFormatStringSuggestion {
-                    captured: captured_arg_span,
-                    len: args.unnamed_args().len().to_string(),
-                    span: span.shrink_to_hi(),
-                    arg,
-                });
+        match err.suggestion {
+            parse::Suggestion::None => {}
+            parse::Suggestion::UsePositional => {
+                let captured_arg_span =
+                    fmt_span.from_inner(InnerSpan::new(err.span.start, err.span.end));
+                if let Ok(arg) = ecx.source_map().span_to_snippet(captured_arg_span) {
+                    let span = match args.unnamed_args().last() {
+                        Some(arg) => arg.expr.span,
+                        None => fmt_span,
+                    };
+                    e.sugg_ = Some(errors::InvalidFormatStringSuggestion::UsePositional {
+                        captured: captured_arg_span,
+                        len: args.unnamed_args().len().to_string(),
+                        span: span.shrink_to_hi(),
+                        arg,
+                    });
+                }
+            }
+            parse::Suggestion::RemoveRawIdent(span) => {
+                if is_source_literal {
+                    let span = fmt_span.from_inner(InnerSpan::new(span.start, span.end));
+                    e.sugg_ = Some(errors::InvalidFormatStringSuggestion::RemoveRawIdent { span })
+                }
             }
         }
         ecx.emit_err(e);