Author: Richard Smith Date: 2020-07-14T10:02:07-07:00 New Revision: bfd643353e6b7ca7b89c0f983ff6a24c36aed276
URL: https://github.com/llvm/llvm-project/commit/bfd643353e6b7ca7b89c0f983ff6a24c36aed276 DIFF: https://github.com/llvm/llvm-project/commit/bfd643353e6b7ca7b89c0f983ff6a24c36aed276.diff LOG: Fix merging of two arity-only pack deductions. If we deduced the arity of a pack in two different ways, but didn't deduce an element of the pack in either of those deductions, we'd merge that element to produce a null template argument, which we'd incorrectly interpret as the merge having failed. Testcase based on one supplied by Hubert Tong. Added: Modified: clang/lib/Sema/SemaTemplateDeduction.cpp clang/test/SemaTemplate/deduction.cpp Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp index f3641afbbf8a..5392be57a3aa 100644 --- a/clang/lib/Sema/SemaTemplateDeduction.cpp +++ b/clang/lib/Sema/SemaTemplateDeduction.cpp @@ -355,7 +355,7 @@ checkDeducedTemplateArguments(ASTContext &Context, TemplateArgument Merged = checkDeducedTemplateArguments( Context, DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()), DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound())); - if (Merged.isNull()) + if (Merged.isNull() && !(XA->isNull() && YA->isNull())) return DeducedTemplateArgument(); NewPack.push_back(Merged); } diff --git a/clang/test/SemaTemplate/deduction.cpp b/clang/test/SemaTemplate/deduction.cpp index 5218543ab8a4..a068bcaea048 100644 --- a/clang/test/SemaTemplate/deduction.cpp +++ b/clang/test/SemaTemplate/deduction.cpp @@ -581,3 +581,19 @@ namespace PR44890 { return w.get<0>(); } } + +namespace merge_size_only_deductions { +#if __cplusplus >= 201703L + // Based on a testcase by Hubert Tong. + template<typename ...> struct X {}; + template<auto ...> struct Y {}; + template<typename T> struct id { using Type = T; }; + + template<typename ...T, typename T::Type ...V> + int f(X<char [V] ...>, Y<V ...>, X<T ...>); + + using size_t = __SIZE_TYPE__; + int a = f(X<char [1], char [2]>(), Y<(size_t)1, (size_t)2>(), X<id<size_t>, id<size_t>>()); + int b = f(X<char [1], char [2]>(), Y<1, 2>(), X<id<int>, id<int>>()); +#endif +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
