r363361 - [clang] Fixing incorrect implicit deduction guides (PR41549)

[Gauthier Harnisch via cfe-commits]

Author: tyker
Date: Fri Jun 14 01:40:04 2019
New Revision: 363361

URL: http://llvm.org/viewvc/llvm-project?rev=363361&view=rev
Log:
[clang] Fixing incorrect implicit deduction guides (PR41549)

Summary:
[[ https://bugs.llvm.org/show_bug.cgi?id=41549 | bug report ]]

Before this patch, implicit deduction guides were generated from the first declaration found by lookup.
With this patch implicit deduction guides are generated from the definition of the class template.
Also added test that was previously failing.

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: cfe-commits, Quuxplusone

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63072

Modified:
    cfe/trunk/lib/Sema/SemaTemplate.cpp
    cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp

Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=363361&r1=363360&r2=363361&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplate.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplate.cpp Fri Jun 14 01:40:04 2019
@@ -2052,6 +2052,12 @@ private:
 
 void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,
                                           SourceLocation Loc) {
+  if (CXXRecordDecl *DefRecord =
+          cast<CXXRecordDecl>(Template->getTemplatedDecl())->getDefinition()) {
+    TemplateDecl *DescribedTemplate = DefRecord->getDescribedClassTemplate();
+    Template = DescribedTemplate ? DescribedTemplate : Template;
+  }
+
   DeclContext *DC = Template->getDeclContext();
   if (DC->isDependentContext())
     return;

Modified: cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp?rev=363361&r1=363360&r2=363361&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp (original)
+++ cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp Fri Jun 14 01:40:04 2019
@@ -489,6 +489,21 @@ static_assert(__is_same(decltype(ta), Te
 }
 #pragma clang diagnostic pop
 
+namespace PR41549 {
+
+template <class H, class P> struct umm;
+
+template <class H = int, class P = int>
+struct umm {
+  umm(H h = 0, P p = 0);
+};
+
+template <class H, class P> struct umm;
+
+umm m(1);
+
+}
+
 #else
 
 // expected-no-diagnostics