[AST] Perform additional canonicalization for DependentSizedArrayType

We treated DependentSizedArrayTypes with the same element type but
differing size expressions as equivalently canonical.  This would lead
to bizarre behavior during template instantiation.

This fixes PR24212.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@243093 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 61bd1077941fdb151f69e3aa393fab5573066ece..ba4bcbc488c9f515a926675b3cc403467b0d0ea1 100644 (file)
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -2759,9 +2759,10 @@ QualType ASTContext::getDependentSizedArrayType(QualType elementType,
   QualType canon = getQualifiedType(QualType(canonTy,0),
                                     canonElementType.Quals);
 
-  // If we didn't need extra canonicalization for the element type,
-  // then just use that as our result.
-  if (QualType(canonElementType.Ty, 0) == elementType)
+  // If we didn't need extra canonicalization for the element type or the size
+  // expression, then just use that as our result.
+  if (QualType(canonElementType.Ty, 0) == elementType &&
+      canonTy->getSizeExpr() == numElements)
     return canon;
 
   // Otherwise, we need to build a type which follows the spelling

diff --git a/test/SemaCXX/alias-template.cpp b/test/SemaCXX/alias-template.cpp
index d5eb27a66132dcda605b54039035a08c2528e5ec..bcfe428c69dd8d2f0c814d7faf43af1d0412fce7 100644 (file)
--- a/test/SemaCXX/alias-template.cpp
+++ b/test/SemaCXX/alias-template.cpp
@@ -168,3 +168,14 @@ namespace SFINAE {
   fail1<int> f1; // expected-note {{here}}
   fail2<E> f2; // expected-note {{here}}
 }
+
+namespace PR24212 {
+struct X {};
+template <int I>
+struct S {
+  template <int J>
+  using T = X[J];
+  using U = T<I>;
+};
+static_assert(__is_same(S<3>::U, X[2]), ""); // expected-error {{static_assert failed}}
+}