Suggest to bind self.x to x when field x may be in format string

Signed-off-by: xizheyin <[email protected]>

Author: xizheyin

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -766,14 +766,15 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     AssocSuggestion::Field(field_span) => {
                         if self_is_available {
                             let source_map = self.r.tcx.sess.source_map();
-                            // check if the field is used in a format string, such as `"{x}"`
-                            let field_is_format_named_arg = source_map
+                            // Check if the field is used in a format string, such as `{x}`.
+                            // Note that both `let y = {x}` and `"{x}"` can match this pattern.
+                            let maybe_field_is_format_named_arg = source_map
                                 .span_to_source(span, |s, start, _| {
                                     Ok(s.get(start - 1..start) == Some("{"))
                                 });
-                            if let Ok(true) = field_is_format_named_arg {
+                            if let Ok(true) = maybe_field_is_format_named_arg {
                                 err.help(
-                                    format!("you might have meant to use the available field in a format string: `\"{{}}\", self.{}`", segment.ident.name),
+                                    format!("you might have meant to use the available field, try to bind it: `let {} = self.{}`", segment.ident.name, segment.ident.name),
                                 );
                             } else {
                                 err.span_suggestion_verbose(

tests/ui/resolve/suggestions/sugg-field-in-format-string-issue-141136.stderr

@@ -14,15 +14,15 @@ error[E0425]: cannot find value `x` in this scope
 LL |         let _ = format!("{x}");
    |                           ^
    |
-   = help: you might have meant to use the available field in a format string: `"{}", self.x`
+   = help: you might have meant to use the available field, try to bind it: `let x = self.x`
 
 error[E0425]: cannot find value `x` in this scope
   --> $DIR/sugg-field-in-format-string-issue-141136.rs:8:27
    |
 LL |         let _ = format!("{x }");
    |                           ^^
    |
-   = help: you might have meant to use the available field in a format string: `"{}", self.x`
+   = help: you might have meant to use the available field, try to bind it: `let x = self.x`
 
 error[E0425]: cannot find value `x` in this scope
   --> $DIR/sugg-field-in-format-string-issue-141136.rs:10:31
@@ -41,15 +41,15 @@ error[E0425]: cannot find value `x` in this scope
 LL |         println!("{x}");
    |                    ^
    |
-   = help: you might have meant to use the available field in a format string: `"{}", self.x`
+   = help: you might have meant to use the available field, try to bind it: `let x = self.x`
 
 error[E0425]: cannot find value `x` in this scope
   --> $DIR/sugg-field-in-format-string-issue-141136.rs:12:18
    |
 LL |         let _ = {x};
    |                  ^
    |
-   = help: you might have meant to use the available field in a format string: `"{}", self.x`
+   = help: you might have meant to use the available field, try to bind it: `let x = self.x`
 
 error: aborting due to 6 previous errors
 

tests/ui/resolve/typo-suggestion-for-variable-with-name-similar-to-struct-field.stderr

@@ -22,7 +22,7 @@ error[E0425]: cannot find value `config` in this scope
 LL |         println!("{config}");
    |                    ^^^^^^ help: a local variable with a similar name exists: `cofig`
    |
-   = help: you might have meant to use the available field in a format string: `"{}", self.config`
+   = help: you might have meant to use the available field, try to bind it: `let config = self.config`
 
 error[E0425]: cannot find value `bah` in this scope
   --> $DIR/typo-suggestion-for-variable-with-name-similar-to-struct-field.rs:33:9