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I have been able to replicate this technique--using the example linked to godbolt from the blog post--working on clang 7 and failing on clang 8-11 (with the fol

by saurik 5y ago

I have been able to replicate this technique--using the example linked to godbolt from the blog post--working on clang 7 and failing on clang 8-11 (with the following error)... but it works again on clang 12 ;P. (I am bisecting overnight to see exactly what fixed it; if anyone sees this and is interested, come back to this thread tomorrow for a follow-up.) note: candidate template ignored: substitution failure [with N = 0]: function 'loophole' with deduced return type cannot be used before it is defined template <int N, typename T = decltype(loophole(A::tag<N>{}))> T get_type(); ~~~~~~~~ ^

saurik 5y ago
commit dd8297b0669f8e69b03ba40171b195b5acf0f963 Author: Richard Smith <richard@metafoo.co.uk> Date: Fri Oct 30 18:30:56 2020 -0700 PR42513: Fix handling of function definitions lazily instantiated from friends. When determining whether a function has a template instantiation pattern, look for other declarations of that function that were instantiated from a friend function definition, rather than assuming that checking for member specialization information on whichever declaration name lookup found will be sufficient. clang/include/clang/AST/Decl.h | 14 +++- clang/lib/AST/Decl.cpp | 61 ++++++++++++-- clang/lib/Sema/SemaDecl.cpp | 84 +++++-------------- clang/lib/Sema/SemaDeclCXX.cpp | 11 +++ clang/lib/Sema/SemaTemplateInstantiateDecl.cpp | 110 ++++++++++++------------- clang/test/SemaTemplate/friend.cpp | 7 ++ 6 files changed, 159 insertions(+), 128 deletions(-) https://bugs.llvm.org/show_bug.cgi?id=42513 https://bugs.llvm.org/show_bug.cgi?id=42513

by saurik 5y ago

saurik 5y ago

commit dd8297b0669f8e69b03ba40171b195b5acf0f963 Author: Richard Smith <richard@metafoo.co.uk> Date: Fri Oct 30 18:30:56 2020 -0700 PR42513: Fix handling of function definitions lazily instantiated from friends. When determining whether a function has a template instantiation pattern, look for other declarations of that function that were instantiated from a friend function definition, rather than assuming that checking for member specialization information on whichever declaration name lookup found will be sufficient. clang/include/clang/AST/Decl.h | 14 +++- clang/lib/AST/Decl.cpp | 61 ++++++++++++-- clang/lib/Sema/SemaDecl.cpp | 84 +++++-------------- clang/lib/Sema/SemaDeclCXX.cpp | 11 +++ clang/lib/Sema/SemaTemplateInstantiateDecl.cpp | 110 ++++++++++++------------- clang/test/SemaTemplate/friend.cpp | 7 ++ 6 files changed, 159 insertions(+), 128 deletions(-) https://bugs.llvm.org/show_bug.cgi?id=42513 https://bugs.llvm.org/show_bug.cgi?id=42513