Unify output of the different "cannot find X" errors

Do not mention the scope where an ident couldn't be resolved (particularly
for macros), and add a primary span label mentioning "this scope" (ideally
we would replace the text with the actual scope name in the future):

```
error: cannot find derive macro `rustfmt`
  --> $DIR/tool-attributes-misplaced-1.rs:4:10
   |
LL | #[derive(rustfmt)]
   |          ^^^^^^^ not found in this scope
```

Author: estebank

compiler/rustc_lint/messages.ftl

@@ -609,7 +609,8 @@ lint_opaque_hidden_inferred_bound_sugg = add this bound
 lint_or_patterns_back_compat = the meaning of the `pat` fragment specifier is changing in Rust 2021, which may affect this macro
     .suggestion = use pat_param to preserve semantics
 
-lint_out_of_scope_macro_calls = cannot find macro `{$path}` in this scope
+lint_out_of_scope_macro_calls = cannot find macro `{$path}`
+    .label = not found in this scope
     .help = import `macro_rules` with `use` to make it callable above its definition
 
 lint_overflowing_bin_hex = literal out of range for `{$ty}`
@@ -650,7 +651,7 @@ lint_pattern_in_foreign = patterns aren't allowed in foreign function declaratio
 lint_private_extern_crate_reexport = extern crate `{$ident}` is private and cannot be re-exported
     .suggestion = consider making the `extern crate` item publicly accessible
 
-lint_proc_macro_derive_resolution_fallback = cannot find {$ns} `{$ident}` in this scope
+lint_proc_macro_derive_resolution_fallback = cannot find {$ns} `{$ident}`
     .label = names from parent modules are not accessible without an explicit import
 
 lint_ptr_null_checks_fn_ptr = function pointers are not nullable, so checking them for null will always return false

compiler/rustc_lint/src/context/diagnostics.rs

@@ -434,8 +434,8 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
             lints::InnerAttributeUnstable::CustomInnerAttribute
         }
         .decorate_lint(diag),
-        BuiltinLintDiag::OutOfScopeMacroCalls { path } => {
-            lints::OutOfScopeMacroCalls { path }.decorate_lint(diag)
+        BuiltinLintDiag::OutOfScopeMacroCalls { span, path } => {
+            lints::OutOfScopeMacroCalls { span, path }.decorate_lint(diag)
         }
     }
 }

compiler/rustc_lint/src/lints.rs

@@ -2917,5 +2917,7 @@ pub struct UnsafeAttrOutsideUnsafeSuggestion {
 #[diag(lint_out_of_scope_macro_calls)]
 #[help]
 pub struct OutOfScopeMacroCalls {
+    #[label]
+    pub span: Span,
     pub path: String,
 }

compiler/rustc_lint_defs/src/lib.rs

@@ -745,6 +745,7 @@ pub enum BuiltinLintDiag {
         is_macro: bool,
     },
     OutOfScopeMacroCalls {
+        span: Span,
         path: String,
     },
 }

compiler/rustc_resolve/messages.ftl

@@ -80,8 +80,8 @@ resolve_cannot_determine_macro_resolution =
 resolve_cannot_find_builtin_macro_with_name =
     cannot find a built-in macro with name `{$ident}`
 
-resolve_cannot_find_ident_in_this_scope =
-    cannot find {$expected} `{$ident}` in this scope
+resolve_cannot_find_ident_in_this_scope = cannot find {$expected} `{$ident}`
+    .label = not found in this scope
 
 resolve_cannot_glob_import_possible_crates =
     cannot glob-import all possible crates

compiler/rustc_resolve/src/errors.rs

@@ -635,6 +635,7 @@ pub(crate) struct ImportsCannotReferTo<'a> {
 #[diag(resolve_cannot_find_ident_in_this_scope)]
 pub(crate) struct CannotFindIdentInThisScope<'a> {
     #[primary_span]
+    #[label]
     pub(crate) span: Span,
     pub(crate) expected: &'a str,
     pub(crate) ident: Ident,

compiler/rustc_resolve/src/late.rs

@@ -3918,7 +3918,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
 
             // There are two different error messages user might receive at
             // this point:
-            // - E0412 cannot find type `{}` in this scope
+            // - E0412 cannot find type `{}`
             // - E0433 failed to resolve: use of undeclared type or module `{}`
             //
             // The first one is emitted for paths in type-position, and the

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -2522,7 +2522,7 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
                 if let Some(generics) = kind.generics() {
                     if span.overlaps(generics.span) {
                         // Avoid the following:
-                        // error[E0405]: cannot find trait `A` in this scope
+                        // error[E0405]: cannot find trait `A`
                         //  --> $DIR/typo-suggestion-named-underscore.rs:CC:LL
                         //   |
                         // L | fn foo<T: A>(x: T) {} // Shouldn't suggest underscore

compiler/rustc_resolve/src/macros.rs

@@ -1071,7 +1071,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     OUT_OF_SCOPE_MACRO_CALLS,
                     path.span,
                     node_id,
-                    BuiltinLintDiag::OutOfScopeMacroCalls { path: pprust::path_to_string(path) },
+                    BuiltinLintDiag::OutOfScopeMacroCalls {
+                        span: path.span,
+                        path: pprust::path_to_string(path),
+                    },
                 );
             }
         }

tests/rustdoc-ui/impl-fn-nesting.stderr

@@ -1,8 +1,8 @@
-error: cannot find macro `unknown_macro` in this scope
+error: cannot find macro `unknown_macro`
   --> $DIR/impl-fn-nesting.rs:32:13
    |
 LL |             unknown_macro!();
-   |             ^^^^^^^^^^^^^
+   |             ^^^^^^^^^^^^^ not found in this scope
 
 error[E0405]: cannot find trait `UnknownBound`
   --> $DIR/impl-fn-nesting.rs:11:13