[PATCH] D97965: [clang] Fix crash when creating deduction guide.

[Adam Czachorowski via Phabricator via cfe-commits]

adamcz created this revision.
adamcz requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

We used to trigger assertion when transforming c-tor with unparsed
default argument. Now we ignore such constructors for this purpose.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D97965

Files:
  clang/lib/Sema/SemaTemplate.cpp
  clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp


Index: clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
===================================================================
--- clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
+++ clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
@@ -416,6 +416,16 @@
 
 }
 
+namespace no_crash_on_default_arg {
+class A {
+  template<typename T> class B {
+    B(int c = 1);
+  };
+  // This used to crash due to unparsed default arg above.
+  B();  // expected-error {{deduction guide declaration without trailing return type}}
+};
+}
+
 #pragma clang diagnostic push
 #pragma clang diagnostic warning "-Wctad-maybe-unsupported"
 namespace test_implicit_ctad_warning {
Index: clang/lib/Sema/SemaTemplate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplate.cpp
+++ clang/lib/Sema/SemaTemplate.cpp
@@ -2494,6 +2494,12 @@
     if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
       continue;
 
+    // Cannot make a deduction guide when unparsed arguments are present.
+    if (std::any_of(CD->param_begin(), CD->param_end(), [](ParmVarDecl *P) {
+          return !P || P->hasUnparsedDefaultArg();
+        }))
+      continue;
+
     Transform.transformConstructor(FTD, CD);
     AddedAny = true;
   }


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