Auto merge of #111552 - matthiaskrgr:rollup-4nidoti, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - #111463 (Better diagnostics for `env!` where variable contains escape)
 - #111477 (better diagnostics for `impl<..> impl Trait for Type`)
 - #111534 (rustdoc-json: Add tests for `#![feature(inherent_associated_types)]`)
 - #111549 ([rustdoc] Convert more GUI tests colors to their original format)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

4 files changed, 42 insertions, 7 deletions

diff --git a/compiler/rustc_builtin_macros/src/env.rs b/compiler/rustc_builtin_macros/src/env.rs
index 58c972738c4..8f64e332861 100644
--- a/compiler/rustc_builtin_macros/src/env.rs
+++ b/compiler/rustc_builtin_macros/src/env.rs
@@ -63,7 +63,8 @@ pub fn expand_env<'cx>(
         Some(exprs) => exprs.into_iter(),
     };
 
-    let Some((var, _style)) = expr_to_string(cx, exprs.next().unwrap(), "expected string literal") else {
+    let var_expr = exprs.next().unwrap();
+    let Some((var, _)) = expr_to_string(cx, var_expr.clone(), "expected string literal") else {
         return DummyResult::any(sp);
     };
 
@@ -71,7 +72,7 @@ pub fn expand_env<'cx>(
         None => None,
         Some(second) => match expr_to_string(cx, second, "expected string literal") {
             None => return DummyResult::any(sp),
-            Some((s, _style)) => Some(s),
+            Some((s, _)) => Some(s),
         },
     };
 
@@ -80,10 +81,15 @@ pub fn expand_env<'cx>(
     cx.sess.parse_sess.env_depinfo.borrow_mut().insert((var, value));
     let e = match value {
         None => {
+            // Use the string literal in the code in the diagnostic to avoid confusing diagnostics,
+            // e.g. when the literal contains escape sequences.
+            let ast::ExprKind::Lit(ast::token::Lit { kind: ast::token::LitKind::Str, symbol: original_var, ..}) = &var_expr.kind else {
+                unreachable!("`expr_to_string` ensures this is a string lit")
+            };
             cx.emit_err(errors::EnvNotDefined {
                 span: sp,
                 msg: custom_msg,
-                var,
+                var: *original_var,
                 help: custom_msg.is_none().then(|| help_for_missing_env_var(var.as_str())),
             });
             return DummyResult::any(sp);
diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
index 1bbf833e3cd..2d0f466e236 100644
--- a/compiler/rustc_parse/messages.ftl
+++ b/compiler/rustc_parse/messages.ftl
@@ -478,6 +478,11 @@ parse_missing_for_in_trait_impl = missing `for` in a trait impl
 
 parse_expected_trait_in_trait_impl_found_type = expected a trait, found type
 
+parse_extra_impl_keyword_in_trait_impl = unexpected `impl` keyword
+    .suggestion = remove the extra `impl`
+    .note = this is parsed as an `impl Trait` type, but a trait is expected at this position
+
+
 parse_non_item_in_item_list = non-item in item list
     .suggestion_use_const_not_let = consider using `const` instead of `let` for associated const
     .label_list_start = item list starts here
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index b6aeaf3d59f..84494eab855 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -1520,6 +1520,16 @@ pub(crate) struct ExpectedTraitInTraitImplFoundType {
 }
 
 #[derive(Diagnostic)]
+#[diag(parse_extra_impl_keyword_in_trait_impl)]
+pub(crate) struct ExtraImplKeywordInTraitImpl {
+    #[primary_span]
+    #[suggestion(code = "", applicability = "maybe-incorrect")]
+    pub extra_impl_kw: Span,
+    #[note]
+    pub impl_trait_span: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(parse_bounds_not_allowed_on_trait_aliases)]
 pub(crate) struct BoundsNotAllowedOnTraitAliases {
     #[primary_span]
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 840cfe90899..dc18d400f1e 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -603,10 +603,24 @@ impl<'a> Parser<'a> {
                 let path = match ty_first.kind {
                     // This notably includes paths passed through `ty` macro fragments (#46438).
                     TyKind::Path(None, path) => path,
-                    _ => {
-                        self.sess.emit_err(errors::ExpectedTraitInTraitImplFoundType {
-                            span: ty_first.span,
-                        });
+                    other => {
+                        if let TyKind::ImplTrait(_, bounds) = other
+                            && let [bound] = bounds.as_slice()
+                        {
+                            // Suggest removing extra `impl` keyword:
+                            // `impl<T: Default> impl Default for Wrapper<T>`
+                            //                   ^^^^^
+                            let extra_impl_kw = ty_first.span.until(bound.span());
+                            self.sess
+                                .emit_err(errors::ExtraImplKeywordInTraitImpl {
+                                    extra_impl_kw,
+                                    impl_trait_span: ty_first.span
+                                });
+                        } else {
+                            self.sess.emit_err(errors::ExpectedTraitInTraitImplFoundType {
+                                span: ty_first.span,
+                            });
+                        }
                         err_path(ty_first.span)
                     }
                 };