2 files changed, 103 insertions, 0 deletions

diff --git a/clang/lib/AST/ODRHash.cpp b/clang/lib/AST/ODRHash.cpp
index 364fd04b83b..ee6950655cf 100644
--- a/clang/lib/AST/ODRHash.cpp
+++ b/clang/lib/AST/ODRHash.cpp
@@ -148,6 +148,8 @@ void ODRHash::AddTemplateArgument(TemplateArgument TA) {
       AddQualType(TA.getAsType());
       break;
     case TemplateArgument::Declaration:
+      AddDecl(TA.getAsDecl());
+      break;
     case TemplateArgument::NullPtr:
     case TemplateArgument::Integral:
       break;
@@ -330,6 +332,15 @@ public:
 
     AddQualType(D->getReturnType());
 
+    const auto* SpecializationArgs = D->getTemplateSpecializationArgs();
+    Hash.AddBoolean(SpecializationArgs);
+    if (SpecializationArgs) {
+      ID.AddInteger(SpecializationArgs->size());
+      for (const TemplateArgument &TA : SpecializationArgs->asArray()) {
+        Hash.AddTemplateArgument(TA);
+      }
+    }
+
     Inherited::VisitFunctionDecl(D);
   }
 
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index a8a4f9328d2..9d10b9ebfbb 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -9450,6 +9450,12 @@ void ASTReader::diagnoseOdrViolations() {
     return Hash.CalculateHash();
   };
 
+  auto ComputeTemplateArgumentODRHash = [&Hash](const TemplateArgument &TA) {
+    Hash.clear();
+    Hash.AddTemplateArgument(TA);
+    return Hash.CalculateHash();
+  };
+
   // Issue any pending ODR-failure diagnostics.
   for (auto &Merge : OdrMergeFailures) {
     // If we've already pointed out a specific problem with this class, don't
@@ -9948,6 +9954,9 @@ void ASTReader::diagnoseOdrViolations() {
         MethodParameterName,
         MethodParameterSingleDefaultArgument,
         MethodParameterDifferentDefaultArgument,
+        MethodNoTemplateArguments,
+        MethodDifferentNumberTemplateArguments,
+        MethodDifferentTemplateArgument,
         TypedefName,
         TypedefType,
         VarName,
@@ -10370,6 +10379,89 @@ void ASTReader::diagnoseOdrViolations() {
           break;
         }
 
+        const auto *FirstTemplateArgs =
+            FirstMethod->getTemplateSpecializationArgs();
+        const auto *SecondTemplateArgs =
+            SecondMethod->getTemplateSpecializationArgs();
+
+        if ((FirstTemplateArgs && !SecondTemplateArgs) ||
+            (!FirstTemplateArgs && SecondTemplateArgs)) {
+          ODRDiagError(FirstMethod->getLocation(),
+                       FirstMethod->getSourceRange(), MethodNoTemplateArguments)
+              << FirstMethodType << FirstName << (FirstTemplateArgs != nullptr);
+          ODRDiagNote(SecondMethod->getLocation(),
+                      SecondMethod->getSourceRange(), MethodNoTemplateArguments)
+              << SecondMethodType << SecondName
+              << (SecondTemplateArgs != nullptr);
+
+          Diagnosed = true;
+          break;
+        }
+
+        if (FirstTemplateArgs && SecondTemplateArgs) {
+          // Remove pack expansions from argument list.
+          auto ExpandTemplateArgumentList =
+              [](const TemplateArgumentList *TAL) {
+                llvm::SmallVector<const TemplateArgument *, 8> ExpandedList;
+                for (const TemplateArgument &TA : TAL->asArray()) {
+                  if (TA.getKind() != TemplateArgument::Pack) {
+                    ExpandedList.push_back(&TA);
+                    continue;
+                  }
+                  for (const TemplateArgument &PackTA : TA.getPackAsArray()) {
+                    ExpandedList.push_back(&PackTA);
+                  }
+                }
+                return ExpandedList;
+              };
+          llvm::SmallVector<const TemplateArgument *, 8> FirstExpandedList =
+              ExpandTemplateArgumentList(FirstTemplateArgs);
+          llvm::SmallVector<const TemplateArgument *, 8> SecondExpandedList =
+              ExpandTemplateArgumentList(SecondTemplateArgs);
+
+          if (FirstExpandedList.size() != SecondExpandedList.size()) {
+            ODRDiagError(FirstMethod->getLocation(),
+                         FirstMethod->getSourceRange(),
+                         MethodDifferentNumberTemplateArguments)
+                << FirstMethodType << FirstName
+                << (unsigned)FirstExpandedList.size();
+            ODRDiagNote(SecondMethod->getLocation(),
+                        SecondMethod->getSourceRange(),
+                        MethodDifferentNumberTemplateArguments)
+                << SecondMethodType << SecondName
+                << (unsigned)SecondExpandedList.size();
+
+            Diagnosed = true;
+            break;
+          }
+
+          bool TemplateArgumentMismatch = false;
+          for (unsigned i = 0, e = FirstExpandedList.size(); i != e; ++i) {
+            const TemplateArgument &FirstTA = *FirstExpandedList[i],
+                                   &SecondTA = *SecondExpandedList[i];
+            if (ComputeTemplateArgumentODRHash(FirstTA) ==
+                ComputeTemplateArgumentODRHash(SecondTA)) {
+              continue;
+            }
+
+            ODRDiagError(FirstMethod->getLocation(),
+                         FirstMethod->getSourceRange(),
+                         MethodDifferentTemplateArgument)
+                << FirstMethodType << FirstName << FirstTA << i + 1;
+            ODRDiagNote(SecondMethod->getLocation(),
+                        SecondMethod->getSourceRange(),
+                        MethodDifferentTemplateArgument)
+                << SecondMethodType << SecondName << SecondTA << i + 1;
+
+            TemplateArgumentMismatch = true;
+            break;
+          }
+
+          if (TemplateArgumentMismatch) {
+            Diagnosed = true;
+            break;
+          }
+        }
         break;
       }
       case TypeAlias: