Replace ad-hoc tracking of pattern for an instantiated class-scope

explicit function specialization with the MemberSpecializationInfo used
everywhere else.

Not NFC: the ad-hoc pattern tracking was not being serialized /
deserialized properly. That's fixed here.

llvm-svn: 359747

1 files changed, 74 insertions, 45 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 64010666299..2c1dbbd7474 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -3375,7 +3375,13 @@ FunctionDecl *FunctionDecl::getInstantiatedFromMemberFunction() const {
 }
 
 MemberSpecializationInfo *FunctionDecl::getMemberSpecializationInfo() const {
-  return TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>();
+  if (auto *MSI =
+          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>())
+    return MSI;
+  if (auto *FTSI = TemplateOrSpecialization
+                       .dyn_cast<FunctionTemplateSpecializationInfo *>())
+    return FTSI->getMemberSpecializationInfo();
+  return nullptr;
 }
 
 void
@@ -3394,6 +3400,8 @@ FunctionTemplateDecl *FunctionDecl::getDescribedFunctionTemplate() const {
 }
 
 void FunctionDecl::setDescribedFunctionTemplate(FunctionTemplateDecl *Template) {
+  assert(TemplateOrSpecialization.isNull() &&
+         "Member function is already a specialization");
   TemplateOrSpecialization = Template;
 }
 
@@ -3402,19 +3410,15 @@ bool FunctionDecl::isImplicitlyInstantiable() const {
   if (isInvalidDecl())
     return false;
 
-  switch (getTemplateSpecializationKind()) {
+  switch (getTemplateSpecializationKindForInstantiation()) {
   case TSK_Undeclared:
   case TSK_ExplicitInstantiationDefinition:
+  case TSK_ExplicitSpecialization:
     return false;
 
   case TSK_ImplicitInstantiation:
     return true;
 
-  // It is possible to instantiate TSK_ExplicitSpecialization kind
-  // if the FunctionDecl has a class scope specialization pattern.
-  case TSK_ExplicitSpecialization:
-    return getClassScopeSpecializationPattern() != nullptr;
-
   case TSK_ExplicitInstantiationDeclaration:
     // Handled below.
     break;
@@ -3437,26 +3441,12 @@ bool FunctionDecl::isImplicitlyInstantiable() const {
 }
 
 bool FunctionDecl::isTemplateInstantiation() const {
-  switch (getTemplateSpecializationKind()) {
-    case TSK_Undeclared:
-    case TSK_ExplicitSpecialization:
-      return false;
-    case TSK_ImplicitInstantiation:
-    case TSK_ExplicitInstantiationDeclaration:
-    case TSK_ExplicitInstantiationDefinition:
-      return true;
-  }
-  llvm_unreachable("All TSK values handled.");
+  // FIXME: Remove this, it's not clear what it means. (Which template
+  // specialization kind?)
+  return clang::isTemplateInstantiation(getTemplateSpecializationKind());
 }
 
 FunctionDecl *FunctionDecl::getTemplateInstantiationPattern() const {
-  // Handle class scope explicit specialization special case.
-  if (getTemplateSpecializationKind() == TSK_ExplicitSpecialization) {
-    if (auto *Spec = getClassScopeSpecializationPattern())
-      return getDefinitionOrSelf(Spec);
-    return nullptr;
-  }
-
   // If this is a generic lambda call operator specialization, its
   // instantiation pattern is always its primary template's pattern
   // even if its primary template was instantiated from another
@@ -3472,6 +3462,15 @@ FunctionDecl *FunctionDecl::getTemplateInstantiationPattern() const {
     return getDefinitionOrSelf(getPrimaryTemplate()->getTemplatedDecl());
   }
 
+  if (MemberSpecializationInfo *Info = getMemberSpecializationInfo()) {
+    if (!clang::isTemplateInstantiation(Info->getTemplateSpecializationKind()))
+      return nullptr;
+    return getDefinitionOrSelf(cast<FunctionDecl>(Info->getInstantiatedFrom()));
+  }
+
+  if (!clang::isTemplateInstantiation(getTemplateSpecializationKind()))
+    return nullptr;
+
   if (FunctionTemplateDecl *Primary = getPrimaryTemplate()) {
     while (Primary->getInstantiatedFromMemberTemplate()) {
       // If we have hit a point where the user provided a specialization of
@@ -3484,9 +3483,6 @@ FunctionDecl *FunctionDecl::getTemplateInstantiationPattern() const {
     return getDefinitionOrSelf(Primary->getTemplatedDecl());
   }
 
-  if (auto *MFD = getInstantiatedFromMemberFunction())
-    return getDefinitionOrSelf(MFD);
-
   return nullptr;
 }
 
@@ -3494,15 +3490,11 @@ FunctionTemplateDecl *FunctionDecl::getPrimaryTemplate() const {
   if (FunctionTemplateSpecializationInfo *Info
         = TemplateOrSpecialization
             .dyn_cast<FunctionTemplateSpecializationInfo*>()) {
-    return Info->Template.getPointer();
+    return Info->getTemplate();
   }
   return nullptr;
 }
 
-FunctionDecl *FunctionDecl::getClassScopeSpecializationPattern() const {
-    return getASTContext().getClassScopeSpecializationPattern(this);
-}
-
 FunctionTemplateSpecializationInfo *
 FunctionDecl::getTemplateSpecializationInfo() const {
   return TemplateOrSpecialization
@@ -3537,15 +3529,19 @@ FunctionDecl::setFunctionTemplateSpecialization(ASTContext &C,
                                                 TemplateSpecializationKind TSK,
                         const TemplateArgumentListInfo *TemplateArgsAsWritten,
                                           SourceLocation PointOfInstantiation) {
+  assert((TemplateOrSpecialization.isNull() ||
+          TemplateOrSpecialization.is<MemberSpecializationInfo *>()) &&
+         "Member function is already a specialization");
   assert(TSK != TSK_Undeclared &&
          "Must specify the type of function template specialization");
-  FunctionTemplateSpecializationInfo *Info
-    = TemplateOrSpecialization.dyn_cast<FunctionTemplateSpecializationInfo*>();
-  if (!Info)
-    Info = FunctionTemplateSpecializationInfo::Create(C, this, Template, TSK,
-                                                      TemplateArgs,
-                                                      TemplateArgsAsWritten,
-                                                      PointOfInstantiation);
+  assert((TemplateOrSpecialization.isNull() ||
+          TSK == TSK_ExplicitSpecialization) &&
+         "Member specialization must be an explicit specialization");
+  FunctionTemplateSpecializationInfo *Info =
+      FunctionTemplateSpecializationInfo::Create(
+          C, this, Template, TSK, TemplateArgs, TemplateArgsAsWritten,
+          PointOfInstantiation,
+          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>());
   TemplateOrSpecialization = Info;
   Template->addSpecialization(Info, InsertPos);
 }
@@ -3596,14 +3592,47 @@ DependentFunctionTemplateSpecializationInfo(const UnresolvedSetImpl &Ts,
 TemplateSpecializationKind FunctionDecl::getTemplateSpecializationKind() const {
   // For a function template specialization, query the specialization
   // information object.
-  FunctionTemplateSpecializationInfo *FTSInfo
-    = TemplateOrSpecialization.dyn_cast<FunctionTemplateSpecializationInfo*>();
-  if (FTSInfo)
+  if (FunctionTemplateSpecializationInfo *FTSInfo =
+          TemplateOrSpecialization
+              .dyn_cast<FunctionTemplateSpecializationInfo *>())
+    return FTSInfo->getTemplateSpecializationKind();
+
+  if (MemberSpecializationInfo *MSInfo =
+          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>())
+    return MSInfo->getTemplateSpecializationKind();
+
+  return TSK_Undeclared;
+}
+
+TemplateSpecializationKind
+FunctionDecl::getTemplateSpecializationKindForInstantiation() const {
+  // This is the same as getTemplateSpecializationKind(), except that for a
+  // function that is both a function template specialization and a member
+  // specialization, we prefer the member specialization information. Eg:
+  //
+  // template<typename T> struct A {
+  //   template<typename U> void f() {}
+  //   template<> void f<int>() {}
+  // };
+  //
+  // For A<int>::f<int>():
+  // * getTemplateSpecializationKind() will return TSK_ExplicitSpecialization
+  // * getTemplateSpecializationKindForInstantiation() will return
+  //       TSK_ImplicitInstantiation
+  //
+  // This reflects the facts that A<int>::f<int> is an explicit specialization
+  // of A<int>::f, and that A<int>::f<int> should be implicitly instantiated
+  // from A::f<int> if a definition is needed.
+  if (FunctionTemplateSpecializationInfo *FTSInfo =
+          TemplateOrSpecialization
+              .dyn_cast<FunctionTemplateSpecializationInfo *>()) {
+    if (auto *MSInfo = FTSInfo->getMemberSpecializationInfo())
+      return MSInfo->getTemplateSpecializationKind();
     return FTSInfo->getTemplateSpecializationKind();
+  }
 
-  MemberSpecializationInfo *MSInfo
-    = TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo*>();
-  if (MSInfo)
+  if (MemberSpecializationInfo *MSInfo =
+          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>())
     return MSInfo->getTemplateSpecializationKind();
 
   return TSK_Undeclared;