PR15597: Fix a confusion between the implicit exception specification and the

uninstantiated exception specification when a special member within a class
template is both defaulted and given an exception specification on its first
declaration.

llvm-svn: 178103

clang/lib/Sema/SemaDeclCXX.cpp

@@ -4372,9 +4372,15 @@ void Sema::CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD) {
   if (Type->hasExceptionSpec()) {
     // Delay the check if this is the first declaration of the special member,
     // since we may not have parsed some necessary in-class initializers yet.
-    if (First)
+    if (First) {
+      // If the exception specification needs to be instantiated, do so now,
+      // before we clobber it with an EST_Unevaluated specification below.
+      if (Type->getExceptionSpecType() == EST_Uninstantiated) {
+        InstantiateExceptionSpec(MD->getLocStart(), MD);
+        Type = MD->getType()->getAs<FunctionProtoType>();
+      }
       DelayedDefaultedMemberExceptionSpecs.push_back(std::make_pair(MD, Type));
-    else
+    } else
       CheckExplicitlyDefaultedMemberExceptionSpec(MD, Type);
   }
 
@@ -11018,6 +11024,9 @@ void Sema::SetDeclDefaulted(Decl *Dcl, SourceLocation DefaultLoc) {
       // on it.
       Pattern->isDefined(Primary);
 
+    // If the method was defaulted on its first declaration, we will have
+    // already performed the checking in CheckCompletedCXXClass. Such a
+    // declaration doesn't trigger an implicit definition.
     if (Primary == Primary->getCanonicalDecl())
       return;
 

clang/lib/Sema/SemaExceptionSpec.cpp

@@ -124,7 +124,7 @@ Sema::ResolveExceptionSpec(SourceLocation Loc, const FunctionProtoType *FPT) {
     return SourceFPT;
 
   // Compute or instantiate the exception specification now.
-  if (FPT->getExceptionSpecType() == EST_Unevaluated)
+  if (SourceFPT->getExceptionSpecType() == EST_Unevaluated)
     EvaluateImplicitExceptionSpec(Loc, cast<CXXMethodDecl>(SourceDecl));
   else
     InstantiateExceptionSpec(Loc, SourceDecl);

clang/test/SemaCXX/cxx0x-defaulted-functions.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -fcxx-exceptions %s
 
 void fn() = default; // expected-error {{only special member}}
 struct foo {
@@ -175,3 +175,16 @@ extern "C" {
  template<typename _Tp> // expected-error {{templates must have C++ linkage}}
  void PR13573(const _Tp&) = delete; // expected-error {{only functions can have deleted definitions}}
 }
+
+namespace PR15597 {
+  template<typename T> struct A {
+    A() noexcept(true) = default;
+    ~A() noexcept(true) = default;
+  };
+  template<typename T> struct B {
+    B() noexcept(false) = default; // expected-error {{does not match the calculated one}}
+    ~B() noexcept(false) = default; // expected-error {{does not match the calculated one}}
+  };
+  A<int> a;
+  B<int> b; // expected-note {{here}}
+}