llvmbot wrote:

<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Corentin Jabot (cor3ntin)

<details>
<summary>Changes</summary>

When a specialization was ambiguous, we would mark it as invalid, even if the 
specialization occured in an immediate context.

This would subsequently lead to scenarios where invalid specialization produced 
no diagnostics, causing crashes during codegen.

Fixes #<!-- -->51866

---
Full diff: https://github.com/llvm/llvm-project/pull/147275.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+1) 
- (modified) clang/lib/Sema/SemaTemplateInstantiate.cpp (-1) 
- (modified) clang/test/SemaTemplate/partial-order.cpp (+26) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9a94c4bcd9980..190eca9a0546e 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -901,6 +901,7 @@ Bug Fixes to C++ Support
 - Fix a bug where private access specifier of overloaded function not 
respected. (#GH107629)
 - Correctly handle allocations in the condition of a ``if 
constexpr``.(#GH120197) (#GH134820)
 - Fixed a crash when handling invalid member using-declaration in C++20+ mode. 
(#GH63254)
+- Fix a crash when trying to instantiate an ambiguous specialization. 
(#GH51866)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp 
b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index a1c7143e3b874..9140f00fcd740 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -4111,7 +4111,6 @@ static ActionResult<CXXRecordDecl *> 
getPatternForClassTemplateSpecialization(
         if (Ambiguous) {
           // Partial ordering did not produce a clear winner. Complain.
           Inst.Clear();
-          ClassTemplateSpec->setInvalidDecl();
           S.Diag(PointOfInstantiation,
                  diag::err_partial_spec_ordering_ambiguous)
               << ClassTemplateSpec;
diff --git a/clang/test/SemaTemplate/partial-order.cpp 
b/clang/test/SemaTemplate/partial-order.cpp
index db2624d1766bc..2619524b147ae 100644
--- a/clang/test/SemaTemplate/partial-order.cpp
+++ b/clang/test/SemaTemplate/partial-order.cpp
@@ -47,3 +47,29 @@ namespace GH132562 {
     // expected-note@-2 {{value of type 'const J' is not implicitly 
convertible to 'int'}}
   } // namespace t3
 } // namespace GH132562
+
+namespace GH51866 {
+
+template <class> struct Trait;
+template <class T>
+    requires T::one
+struct Trait<T> {}; // #gh51866-one
+template <class T>
+    requires T::two
+struct Trait<T> {}; // #gh51866-two
+
+struct Y {
+    static constexpr bool one = true;
+    static constexpr bool two = true;
+};
+
+template <class T>
+concept C = sizeof(Trait<T>) != 0;
+
+static_assert(!C<Y>);
+
+Trait<Y> t;
+// expected-error@-1{{ambiguous partial specializations of 
'Trait<GH51866::Y>'}}
+// expected-note@#gh51866-one{{partial specialization matches}}
+// expected-note@#gh51866-two{{partial specialization matches}}
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/147275
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

Reply via email to