[PATCH] D109406: [clang] fix transformation of template arguments of 'auto' type constraints

[Matheus Izvekov via Phabricator via cfe-commits]

mizvekov created this revision.
mizvekov published this revision for review.
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See PR48617.

When assigning the new template arguments to the new TypeLoc, we were looping
on the argument count of the original TypeLoc instead of the new one,
which can be different when packs are present.

Signed-off-by: Matheus Izvekov <mizvekov at gmail.com>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109406

Files:
  clang/lib/Sema/TreeTransform.h
  clang/test/CXX/dcl/dcl.spec/dcl.type/dcl.spec.auto/p6.cpp


Index: clang/test/CXX/dcl/dcl.spec/dcl.type/dcl.spec.auto/p6.cpp
===================================================================
--- clang/test/CXX/dcl/dcl.spec/dcl.type/dcl.spec.auto/p6.cpp
+++ clang/test/CXX/dcl/dcl.spec/dcl.type/dcl.spec.auto/p6.cpp
@@ -76,3 +76,25 @@
   template<class> concept d = true;
   d<,> auto e = 0; // expected-error{{expected expression}}
 }
+
+namespace PR48617 {
+  template <typename...> concept C = true;
+  template <typename...> class A {};
+
+  template <typename... Ts> C<Ts...> auto e(A<Ts...>) { return 0; }
+
+  // FIXME: The error here does not make sense.
+  template auto e<>(A<>);
+  // expected-error at -1 {{explicit instantiation of 'e' does not refer to a function template}}
+  // expected-note at -5  {{candidate template ignored: failed template argument deduction}}
+
+  // FIXME: Should be able to instantiate this with no errors.
+  template C<int> auto e<int>(A<int>);
+  // expected-error at -1 {{explicit instantiation of 'e' does not refer to a function template}}
+  // expected-note at -10 {{candidate template ignored: could not match 'C<int, Ts...> auto' against 'C<int> auto'}}
+  
+  template C<> auto e<>(A<>);
+
+  template <typename... Ts> A<Ts...> c(Ts...);
+  int f = e(c(1, 2));
+}
Index: clang/lib/Sema/TreeTransform.h
===================================================================
--- clang/lib/Sema/TreeTransform.h
+++ clang/lib/Sema/TreeTransform.h
@@ -6578,7 +6578,7 @@
   NewTL.setFoundDecl(TL.getFoundDecl());
   NewTL.setLAngleLoc(TL.getLAngleLoc());
   NewTL.setRAngleLoc(TL.getRAngleLoc());
-  for (unsigned I = 0; I < TL.getNumArgs(); ++I)
+  for (unsigned I = 0; I < NewTL.getNumArgs(); ++I)
     NewTL.setArgLocInfo(I, NewTemplateArgs.arguments()[I].getLocInfo());
 
   return Result;


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