Implement explicit specialization of explicitly-defaulted constructors.

The general out-of-line case (including explicit instantiation mostly
works except that the definition is being lost somewhere between the AST
and CodeGen, so the definition is never emitted.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131933 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 80 insertions, 89 deletions

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index ec11838c84..81d976f4e8 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -1438,7 +1438,7 @@ bool FunctionDecl::hasTrivialBody() const
 
 bool FunctionDecl::isDefined(const FunctionDecl *&Definition) const {
   for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I) {
-    if (I->IsDeleted || I->Body || I->IsLateTemplateParsed) {
+    if (I->IsDeleted || I->IsDefaulted || I->Body || I->IsLateTemplateParsed) {
       Definition = I->IsDeleted ? I->getCanonicalDecl() : *I;
       return true;
     }
diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp
index 4e4819e9fc..a706f439a1 100644
--- a/lib/Parse/Parser.cpp
+++ b/lib/Parse/Parser.cpp
@@ -832,78 +832,13 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
   if (FTI.isKNRPrototype())
     ParseKNRParamDeclarations(D);
 
-  if (Tok.is(tok::equal)) {
-    assert(getLang().CPlusPlus && "Only C++ function definitions have '='");
-    ConsumeToken();
-
-    Decl *Decl = 0;
-    // Here we complete the declaration as if it were normal
-    switch (TemplateInfo.Kind) {
-    case ParsedTemplateInfo::NonTemplate:
-      Decl = Actions.ActOnDeclarator(getCurScope(), D, true);
-      break;
-
-    case ParsedTemplateInfo::Template:
-    case ParsedTemplateInfo::ExplicitSpecialization:
-      Decl = Actions.ActOnTemplateDeclarator(getCurScope(),
-                                   MultiTemplateParamsArg(Actions,
-                                          TemplateInfo.TemplateParams->data(),
-                                          TemplateInfo.TemplateParams->size()),
-                                             D);
-      break;
-
-    case ParsedTemplateInfo::ExplicitInstantiation: {
-      DeclResult Result
-        = Actions.ActOnExplicitInstantiation(getCurScope(),
-                                             TemplateInfo.ExternLoc,
-                                             TemplateInfo.TemplateLoc,
-                                             D);
-      if (Result.isInvalid()) {
-        SkipUntil(tok::semi);
-        return 0;
-      }
-
-      Decl = Result.get();
-      break;
-    }
-    }
-      
-    bool Delete = false;
-    SourceLocation KWLoc;
-    if (Tok.is(tok::kw_delete)) {
-      if (!getLang().CPlusPlus0x)
-        Diag(Tok, diag::warn_deleted_function_accepted_as_extension);
-
-      KWLoc = ConsumeToken();
-      Actions.SetDeclDeleted(Decl, KWLoc);
-      Delete = true;
-    } else if (Tok.is(tok::kw_default)) {
-      if (!getLang().CPlusPlus0x)
-        Diag(Tok, diag::warn_defaulted_function_accepted_as_extension);
-
-      KWLoc = ConsumeToken();
-      Actions.SetDeclDefaulted(Decl, KWLoc);
-    } else {
-      llvm_unreachable("function definition after = not 'delete' or 'default'");
-    }
-
-    if (Tok.is(tok::comma)) {
-      Diag(KWLoc, diag::err_default_delete_in_multiple_declaration)
-        << Delete;
-      SkipUntil(tok::semi);
-    } else {
-      ExpectAndConsume(tok::semi, diag::err_expected_semi_after,
-                       Delete ? "delete" : "default", tok::semi);
-    }
-
-    return Decl;
-  }
 
   // We should have either an opening brace or, in a C++ constructor,
   // we may have a colon.
   if (Tok.isNot(tok::l_brace) && 
       (!getLang().CPlusPlus ||
-       (Tok.isNot(tok::colon) && Tok.isNot(tok::kw_try)))) {
+       (Tok.isNot(tok::colon) && Tok.isNot(tok::kw_try) &&
+        Tok.isNot(tok::equal)))) {
     Diag(Tok, diag::err_expected_fn_body);
 
     // Skip over garbage, until we get to '{'.  Don't eat the '{'.
@@ -951,7 +886,6 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
     return DP;
   }
 
-
   // Enter a scope for the function body.
   ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);
 
@@ -972,6 +906,43 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
   // safe because we're always the sole owner.
   D.getMutableDeclSpec().abort();
 
+  if (Tok.is(tok::equal)) {
+    assert(getLang().CPlusPlus && "Only C++ function definitions have '='");
+    ConsumeToken();
+
+    Actions.ActOnFinishFunctionBody(Res, 0, false);
+ 
+    bool Delete = false;
+    SourceLocation KWLoc;
+    if (Tok.is(tok::kw_delete)) {
+      if (!getLang().CPlusPlus0x)
+        Diag(Tok, diag::warn_deleted_function_accepted_as_extension);
+
+      KWLoc = ConsumeToken();
+      Actions.SetDeclDeleted(Res, KWLoc);
+      Delete = true;
+    } else if (Tok.is(tok::kw_default)) {
+      if (!getLang().CPlusPlus0x)
+        Diag(Tok, diag::warn_defaulted_function_accepted_as_extension);
+
+      KWLoc = ConsumeToken();
+      Actions.SetDeclDefaulted(Res, KWLoc);
+    } else {
+      llvm_unreachable("function definition after = not 'delete' or 'default'");
+    }
+
+    if (Tok.is(tok::comma)) {
+      Diag(KWLoc, diag::err_default_delete_in_multiple_declaration)
+        << Delete;
+      SkipUntil(tok::semi);
+    } else {
+      ExpectAndConsume(tok::semi, diag::err_expected_semi_after,
+                       Delete ? "delete" : "default", tok::semi);
+    }
+
+    return Res;
+  }
+
   if (Tok.is(tok::kw_try))
     return ParseFunctionTryBlock(Res, BodyScope);
 
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 9d8ab641f1..e8f2f57a22 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -6011,7 +6011,8 @@ CXXConstructorDecl *Sema::DeclareImplicitDefaultConstructor(
 void Sema::DefineImplicitDefaultConstructor(SourceLocation CurrentLocation,
                                             CXXConstructorDecl *Constructor) {
   assert((Constructor->isDefaulted() && Constructor->isDefaultConstructor() &&
-          !Constructor->isUsed(false) && !Constructor->isDeleted()) &&
+          !Constructor->doesThisDeclarationHaveABody() &&
+          !Constructor->isDeleted()) &&
     "DefineImplicitDefaultConstructor - call it for implicit default ctor");
 
   CXXRecordDecl *ClassDecl = Constructor->getParent();
@@ -6303,7 +6304,8 @@ CXXDestructorDecl *Sema::DeclareImplicitDestructor(CXXRecordDecl *ClassDecl) {
 
 void Sema::DefineImplicitDestructor(SourceLocation CurrentLocation,
                                     CXXDestructorDecl *Destructor) {
-  assert((Destructor->isDefaulted() && !Destructor->isUsed(false)) &&
+  assert((Destructor->isDefaulted() &&
+          !Destructor->doesThisDeclarationHaveABody()) &&
          "DefineImplicitDestructor - call it for implicit default dtor");
   CXXRecordDecl *ClassDecl = Destructor->getParent();
   assert(ClassDecl && "DefineImplicitDestructor - invalid destructor");
@@ -6750,7 +6752,7 @@ void Sema::DefineImplicitCopyAssignment(SourceLocation CurrentLocation,
   assert((CopyAssignOperator->isDefaulted() && 
           CopyAssignOperator->isOverloadedOperator() &&
           CopyAssignOperator->getOverloadedOperator() == OO_Equal &&
-          !CopyAssignOperator->isUsed(false)) &&
+          !CopyAssignOperator->doesThisDeclarationHaveABody()) &&
          "DefineImplicitCopyAssignment called for wrong function");
 
   CXXRecordDecl *ClassDecl = CopyAssignOperator->getParent();
@@ -7228,7 +7230,7 @@ void Sema::DefineImplicitCopyConstructor(SourceLocation CurrentLocation,
                                    CXXConstructorDecl *CopyConstructor) {
   assert((CopyConstructor->isDefaulted() &&
           CopyConstructor->isCopyConstructor() &&
-          !CopyConstructor->isUsed(false)) &&
+          !CopyConstructor->doesThisDeclarationHaveABody()) &&
          "DefineImplicitCopyConstructor - call it for implicit copy ctor");
 
   CXXRecordDecl *ClassDecl = CopyConstructor->getParent();
@@ -8673,8 +8675,15 @@ void Sema::SetDeclDefaulted(Decl *Dcl, SourceLocation DefaultLoc) {
     MD->setDefaulted();
     MD->setExplicitlyDefaulted();
 
-    // We'll check it when the record is done
-    if (MD == MD->getCanonicalDecl())
+    // If this definition appears within the record, do the checking when
+    // the record is complete.
+    const FunctionDecl *Primary = MD;
+    if (MD->getTemplatedKind() != FunctionDecl::TK_NonTemplate)
+      // Find the uninstantiated declaration that actually had the '= default'
+      // on it.
+      MD->getTemplateInstantiationPattern()->isDefined(Primary);
+
+    if (Primary == Primary->getCanonicalDecl())
       return;
 
     switch (Member) {
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index fb34d9f1da..2481bd004d 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2320,6 +2320,9 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
   Stmt *Pattern = 0;
   if (PatternDecl)
     Pattern = PatternDecl->getBody(PatternDecl);
+  if (!Pattern)
+    // Try to find a defaulted definition
+    PatternDecl->isDefined(PatternDecl);
 
   // Postpone late parsed template instantiations.
   if (PatternDecl && PatternDecl->isLateTemplateParsed() &&
@@ -2337,7 +2340,7 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
     Pattern = PatternDecl->getBody(PatternDecl);
   }
 
-  if (!Pattern) {
+  if (!Pattern && !PatternDecl->isDefaulted()) {
     if (DefinitionRequired) {
       if (Function->getPrimaryTemplate())
         Diag(PointOfInstantiation, 
@@ -2432,21 +2435,29 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
   MultiLevelTemplateArgumentList TemplateArgs =
     getTemplateInstantiationArgs(Function, 0, false, PatternDecl);
 
-  // If this is a constructor, instantiate the member initializers.
-  if (const CXXConstructorDecl *Ctor =
-        dyn_cast<CXXConstructorDecl>(PatternDecl)) {
-    InstantiateMemInitializers(cast<CXXConstructorDecl>(Function), Ctor,
-                               TemplateArgs);
-  }
+  if (PatternDecl->isDefaulted()) {
+    ActOnFinishFunctionBody(Function, 0, /*IsInstantiation=*/true);
 
-  // Instantiate the function body.
-  StmtResult Body = SubstStmt(Pattern, TemplateArgs);
+    SetDeclDefaulted(Function, PatternDecl->getLocation());
 
-  if (Body.isInvalid())
-    Function->setInvalidDecl();
-  
-  ActOnFinishFunctionBody(Function, Body.get(),
-                          /*IsInstantiation=*/true);
+    return;
+  } else {
+    // If this is a constructor, instantiate the member initializers.
+    if (const CXXConstructorDecl *Ctor =
+          dyn_cast<CXXConstructorDecl>(PatternDecl)) {
+      InstantiateMemInitializers(cast<CXXConstructorDecl>(Function), Ctor,
+                                 TemplateArgs);
+    }
+
+    // Instantiate the function body.
+    StmtResult Body = SubstStmt(Pattern, TemplateArgs);
+
+    if (Body.isInvalid())
+      Function->setInvalidDecl();
+    
+    ActOnFinishFunctionBody(Function, Body.get(),
+                            /*IsInstantiation=*/true);
+  }
 
   PerformDependentDiagnostics(PatternDecl, TemplateArgs);