[modules] When loading a template specialization, re-canonicalize its template

arguments because the reloaded form might have become non-canonical across the
serialization/deserialization step (this particularly happens when the
canonical form of the type involves an expression).

llvm-svn: 244409

1 files changed, 15 insertions, 5 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 2412d04666f..ff771fd00a3 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -7568,9 +7568,19 @@ ASTReader::ReadTemplateName(ModuleFile &F, const RecordData &Record,
   llvm_unreachable("Unhandled template name kind!");
 }
 
-TemplateArgument
-ASTReader::ReadTemplateArgument(ModuleFile &F,
-                                const RecordData &Record, unsigned &Idx) {
+TemplateArgument ASTReader::ReadTemplateArgument(ModuleFile &F,
+                                                 const RecordData &Record,
+                                                 unsigned &Idx,
+                                                 bool Canonicalize) {
+  if (Canonicalize) {
+    // The caller wants a canonical template argument. Sometimes the AST only
+    // wants template arguments in canonical form (particularly as the template
+    // argument lists of template specializations) so ensure we preserve that
+    // canonical form across serialization.
+    TemplateArgument Arg = ReadTemplateArgument(F, Record, Idx, false);
+    return Context.getCanonicalTemplateArgument(Arg);
+  }
+
   TemplateArgument::ArgKind Kind = (TemplateArgument::ArgKind)Record[Idx++];
   switch (Kind) {
   case TemplateArgument::Null:
@@ -7634,11 +7644,11 @@ void
 ASTReader::
 ReadTemplateArgumentList(SmallVectorImpl<TemplateArgument> &TemplArgs,
                          ModuleFile &F, const RecordData &Record,
-                         unsigned &Idx) {
+                         unsigned &Idx, bool Canonicalize) {
   unsigned NumTemplateArgs = Record[Idx++];
   TemplArgs.reserve(NumTemplateArgs);
   while (NumTemplateArgs--)
-    TemplArgs.push_back(ReadTemplateArgument(F, Record, Idx));
+    TemplArgs.push_back(ReadTemplateArgument(F, Record, Idx, Canonicalize));
 }
 
 /// \brief Read a UnresolvedSet structure.