Exception specification mismatch in explicit instantiation

[ABataev]

Summary

According to C++ standard if an exception-specification is specified in an explicit instantiation directive, it shall be compatible with the exception-specifications of other declarations of that function. This patch adds checks for this.

[rsmith]

include/clang/Basic/DiagnosticSemaKinds.td

3654–3657 ↗

(On Diff #15013)

"deduced" is not correct here; "instantiated" would be better.

lib/Sema/SemaTemplate.cpp

7637–7639 ↗

(On Diff #15013)

This is duplicating work the function has already done. (See variables T and R declared earlier.) Instead of checking whether the declarator has an exception specification, you can instead check whether R is a FunctionProtoType with an exception specification.

[ABataev]

Richard, thanks for the review.

include/clang/Basic/DiagnosticSemaKinds.td

3654–3657 ↗

(On Diff #15013)

Ok, fixed

lib/Sema/SemaTemplate.cpp

7637–7639 ↗

(On Diff #15013)

Agree, missed these variables somehow.

[ABataev]

Fixed error and warning messages, use previously defined variables.

[rsmith]

LGTM with a tweak to the testing.

test/SemaTemplate/explicit-instantiation-cxx11.cpp

1 ↗

(On Diff #15549)

Rather than copying this test, give the original test two RUN: lines. Use #if __cplusplus >= 201103L to disable the C++11-specific bits for the C++98 run of the test.

[ABataev]

Closed by commit rL221448 (authored by @ABataev).

cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td

def err_explicit_instantiation_declaration_after_definition : Error<
   "explicit instantiation declaration (with 'extern') follows explicit "
   "instantiation definition (without 'extern')">;
 def note_explicit_instantiation_definition_here : Note<
   "explicit instantiation definition is here">;
 def err_invalid_var_template_spec_type : Error<"type %2 "
   "of %select{explicit instantiation|explicit specialization|"
   "partial specialization|redeclaration}0 of %1 does not match"
   " expected type %3">;
+def err_mismatched_exception_spec_explicit_instantiation : Error<
+  "exception specification in explicit instantiation does not match instantiated one">;
+def ext_mismatched_exception_spec_explicit_instantiation : ExtWarn<
+  "exception specification in explicit instantiation does not match instantiated one">,
+  InGroup<Microsoft>;
   
 // C++ typename-specifiers
 def err_typename_nested_not_found : Error<"no type named %0 in %1">;
 def err_typename_nested_not_found_enable_if : Error<
   "no type named 'type' in %0; 'enable_if' cannot be used to disable "
   "this declaration">;
 def err_typename_nested_not_type : Error<
     "typename specifier refers to non-type member %0 in %1">;

cfe/trunk/lib/Sema/SemaTemplate.cpp

UnresolvedSetIterator Result = getMostSpecialized(
       PDiag(diag::note_explicit_instantiation_candidate));
 
   if (Result == Matches.end())
     return true;
 
   // Ignore access control bits, we don't need them for redeclaration checking.
   FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
 
+  // C++11 [except.spec]p4
+  // In an explicit instantiation an exception-specification may be specified,
+  // but is not required.
+  // If an exception-specification is specified in an explicit instantiation
+  // directive, it shall be compatible with the exception-specifications of
+  // other declarations of that function.
+  if (auto *FPT = R->getAs<FunctionProtoType>())
+    if (FPT->hasExceptionSpec()) {
+      unsigned DiagID =
+          diag::err_mismatched_exception_spec_explicit_instantiation;
+      if (getLangOpts().MicrosoftExt)
+        DiagID = diag::ext_mismatched_exception_spec_explicit_instantiation;
+      bool Result = CheckEquivalentExceptionSpec(
+          PDiag(DiagID) << Specialization->getType(),
+          PDiag(diag::note_explicit_instantiation_here),
+          Specialization->getType()->getAs<FunctionProtoType>(),
+          Specialization->getLocation(), FPT, D.getLocStart());
+      // In Microsoft mode, mismatching exception specifications just cause a
+      // warning.
+      if (!getLangOpts().MicrosoftExt && Result)
+        return true;
+    }
+
   if (Specialization->getTemplateSpecializationKind() == TSK_Undeclared) {
     Diag(D.getIdentifierLoc(),
          diag::err_explicit_instantiation_member_function_not_instantiated)
       << Specialization
       << (Specialization->getTemplateSpecializationKind() ==
           TSK_ExplicitSpecialization);
     Diag(Specialization->getLocation(), diag::note_explicit_instantiation_here);
     return true;

cfe/trunk/test/SemaTemplate/explicit-instantiation.cpp

-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -fexceptions -fcxx-exceptions %s
+// RUN: %clang_cc1 -fsyntax-only -verify -fexceptions -fcxx-exceptions -std=c++11 %s
 
 template void *; // expected-error{{expected unqualified-id}}
 
 template typedef void f0; // expected-error{{explicit instantiation of typedef}}
 
 int v0; // expected-note{{refers here}}
 template int v0; // expected-error{{does not refer}}
 
 template<typename T>
 struct X0 {
   static T value;
   
   T f0(T x) {
     return x + 1;  // expected-error{{invalid operands}}
-  } 
-  T* f0(T*, T*) { return T(); } // expected-warning{{expression which evaluates to zero treated as a null pointer constant of type 'int *'}}
+  }
+  T *f0(T *, T *) { return T(); } // expected-warning 0-1 {{expression which evaluates to zero treated as a null pointer constant of type 'int *'}} expected-error 0-1 {{cannot initialize return object of type 'int *' with an rvalue of type 'int'}}
 
   template <typename U> T f0(T, U) { return T(); } // expected-note-re {{candidate template ignored: could not match 'int (int, U){{( __attribute__\(\(thiscall\)\))?}}' against 'int (int){{( __attribute__\(\(thiscall\)\))?}} const'}} \
                                                    // expected-note {{candidate template ignored: could not match 'int' against 'int *'}}
 };
 
 template<typename T>
 T X0<T>::value; // expected-error{{no matching constructor}}
 
 template int X0<int>::value;
 
-struct NotDefaultConstructible { // expected-note{{candidate constructor (the implicit copy constructor)}}
+struct NotDefaultConstructible { // expected-note{{candidate constructor (the implicit copy constructor)}} expected-note 0-1 {{candidate constructor (the implicit move constructor)}}
   NotDefaultConstructible(int); // expected-note{{candidate constructor}}
 };
 
 template NotDefaultConstructible X0<NotDefaultConstructible>::value; // expected-note{{instantiation}}
 
 template int X0<int>::f0(int);
 template int* X0<int>::f0(int*, int*); // expected-note{{in instantiation of member function 'X0<int>::f0' requested here}}
 template int X0<int>::f0(int, float);
namespace undefined_static_data_member {
   template<typename T> int C<T>::a;
   template<typename T> template<typename U> int C<T>::b; // expected-warning {{extension}}
   template<typename U> int D::c; // expected-warning {{extension}}
 
   template int C<int>::a;
   template int C<int>::b<int>;
   template int D::c<int>;
 }
+
+// expected-note@+1 3-4 {{explicit instantiation refers here}}
+template <class T> void Foo(T i) throw(T) { throw i; }
+// expected-error@+1 {{exception specification in explicit instantiation does not match instantiated one}}
+template void Foo(int a) throw(char);
+// expected-error@+1 {{exception specification in explicit instantiation does not match instantiated one}}
+template void Foo(double a) throw();
+// expected-error@+1 1 {{exception specification in explicit instantiation does not match instantiated one}}
+template void Foo(long a) throw(long, char);
+template void Foo(float a);
+#if __cplusplus >= 201103L
+// expected-error@+1 0-1 {{exception specification in explicit instantiation does not match instantiated one}}
+template void Foo(double a) noexcept;
+#endif