[Clang][Sema] Reject declaring an alias template with the same name as its template parameter. #123533
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@llvm/pr-subscribers-clang Author: Valentyn Yukhymenko (BaLiKfromUA) ChangesFixes llvm#123423 How did I test it? Modified existing test and checked an example from the issue manually. Full diff: https://github.com/llvm/llvm-project/pull/123533.diff 3 Files Affected:
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index aa1c02d04f7caa..29e40b4ecab412 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -956,6 +956,7 @@ Bug Fixes to C++ Support
- Fixed a crash caused by the incorrect construction of template arguments for CTAD alias guides when type
constraints are applied. (#GH122134)
- Fixed canonicalization of pack indexing types - Clang did not always recognized identical pack indexing. (#GH123033)
+- Clang now rejects declaring an alias template with the same name as its template parameter. (#GH123423)
Bug Fixes to AST Handling
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index a867ed73bd4033..4e43a8397cec4e 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13464,6 +13464,14 @@ Decl *Sema::ActOnAliasDeclaration(Scope *S, AccessSpecifier AS,
}
TemplateParameterList *TemplateParams = TemplateParamLists[0];
+ // Check shadowing of a template parameter name
+ for (NamedDecl *TP : TemplateParams->asArray()) {
+ if (NameInfo.getName() == TP->getDeclName()) {
+ DiagnoseTemplateParameterShadow(Name.StartLocation, TP);
+ return nullptr;
+ }
+ }
+
// Check that we can declare a template here.
if (CheckTemplateDeclScope(S, TemplateParams))
return nullptr;
diff --git a/clang/test/SemaCXX/alias-template.cpp b/clang/test/SemaCXX/alias-template.cpp
index 5189405e23db56..97134d2f3a96ad 100644
--- a/clang/test/SemaCXX/alias-template.cpp
+++ b/clang/test/SemaCXX/alias-template.cpp
@@ -65,7 +65,8 @@ namespace InFunctions {
template<typename...T> struct S3 { // expected-note {{template parameter is declared here}}
template<typename Z> using T = int; // expected-error {{declaration of 'T' shadows template parameter}}
};
- template<typename Z> using Z = Z;
+ template<typename Z> // expected-note {{template parameter is declared here}}
+ using Z = Z; // expected-error {{declaration of 'Z' shadows template parameter}}
}
namespace ClassNameRedecl {
@@ -191,4 +192,4 @@ int g = sfinae_me<int>(); // expected-error{{no matching function for call to 's
namespace NullExceptionDecl {
template<int... I> auto get = []() { try { } catch(...) {}; return I; }; // expected-error{{initializer contains unexpanded parameter pack 'I'}}
-}
+}
\ No newline at end of file
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…template parameter. Fixes llvm#123423
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/73/builds/12403 Here is the relevant piece of the build log for the reference |
Move changing of declaration scope to the moment after
LookupNameto avoid missing template parameters, but keep the behavior similar to thetypedefimplementation.Fixes #123423