[clang] Informative error for lifetimebound in decl-spec (#118567)

Emit a bit more informative error when the `[[clang::lifetimebound]]`
attribute is wrongly appearing on a decl-spec:

```
'lifetimebound' attribute only applies to parameters and implicit
object parameters
```

instead of:

```
'lifetimebound' attribute cannot be applied to types
```

The new error is also consistent with the diagnostic emitted when the
attribute is misplaced in other parts of a declarator.

1 files changed, 8 insertions, 2 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 937a94b..7f3f6d5 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -3706,8 +3706,14 @@ void Parser::ParseDeclarationSpecifiers(
           if (PA.isTypeAttr() && PA.getKind() != ParsedAttr::AT_LifetimeBound &&
               PA.getKind() != ParsedAttr::AT_AnyX86NoCfCheck)
             continue;
-          Diag(PA.getLoc(), diag::err_attribute_not_type_attr)
-              << PA << PA.isRegularKeywordAttribute();
+
+          if (PA.getKind() == ParsedAttr::AT_LifetimeBound)
+            Diag(PA.getLoc(), diag::err_attribute_wrong_decl_type_str)
+                << PA << PA.isRegularKeywordAttribute()
+                << "parameters and implicit object parameters";
+          else
+            Diag(PA.getLoc(), diag::err_attribute_not_type_attr)
+                << PA << PA.isRegularKeywordAttribute();
           PA.setInvalid();
         }