[PATCH] D147495: [Clang][Attributes] Add MeaningfulToClassTemplateDefinition to unavailable attribute

[Shafik Yaghmour via Phabricator via cfe-commits]

shafik created this revision.
shafik added reviewers: rsmith, aaron.ballman, erichkeane.
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There may be cases in which we want to diagnose a type as unavailable but it may not be complete at the time. Setting `MeaningfulToClassTemplateDefinition` fixes this issue.

This fixes: https://github.com/llvm/llvm-project/issues/61815


https://reviews.llvm.org/D147495

Files:
  clang/include/clang/Basic/Attr.td
  clang/test/SemaCXX/attr-unavailable.cpp


Index: clang/test/SemaCXX/attr-unavailable.cpp
===================================================================
--- clang/test/SemaCXX/attr-unavailable.cpp
+++ clang/test/SemaCXX/attr-unavailable.cpp
@@ -172,3 +172,13 @@
 
 template <class T>
 int phase_one_unavailable2(int x = unavailable_int()) __attribute__((unavailable)) {}
+
+namespace GH61815 {
+template <class _ValueType = int>
+class __attribute__((unavailable)) polymorphic_allocator {}; // expected-note 2 {{'polymorphic_allocator<void>' has been explicitly marked unavailable here}}
+
+void f() {
+  polymorphic_allocator<void> a; // expected-error {{'polymorphic_allocator<void>' is unavailable}}
+  polymorphic_allocator<void> b; // expected-error {{'polymorphic_allocator<void>' is unavailable}}
+}
+}
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -2848,6 +2848,7 @@
                  "IR_ARCInitReturnsUnrelated",
                  "IR_ARCFieldWithOwnership"], 1, /*fake*/ 1>];
   let Documentation = [Undocumented];
+  let MeaningfulToClassTemplateDefinition = 1;
 }
 
 def DiagnoseIf : InheritableAttr {


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