Add new ASTMatcher that matches dynamic exception specifications.

[hintonda]

Summary

Add new ASTMatcher that matches dynamic exception specifications.

[alexfh]

Please add tests, re-generate documentation and add the matcher to the dynamic matchers registry. See http://reviews.llvm.org/D19871 for an example.

[hintonda]

• Added test, re-generated documentation, and add new matcher to the dynamic matchers registry.

[aaron.ballman]

include/clang/ASTMatchers/ASTMatchers.h

3229

It's a bit odd to expose this on the declaration instead of the type since the AST carries this information on the type, not the declaration. I definitely see the utility in not having to go from the decl to the type in an AST matcher, though. Can you expose it on both FunctionDecl and FunctionProtoType instead?

[hintonda]

include/clang/ASTMatchers/ASTMatchers.h

3229

It's modeled on the isNoThrow matcher directly below which used FunctionDecl, so I used it for this one too.

Did you want me change this one to use FunctionProtoType or add 2 matchers, one using FunctionDecl and another one using FunctionProtoType?

[aaron.ballman]

LGTM!

include/clang/ASTMatchers/ASTMatchers.h

3229

Ah, good point about isNoThrow. I would say leave it as FunctionDecl for now and maybe a follow-on patch (not requesting you do this work, btw) can convert it to be a polymorphic matcher that accepts FunctionDecl and FunctionProtoType.

[hintonda]

Great, thanks. Btw, I don't have commit access, so could you land it for me?

[hintonda]

• Added new isThrow matcher to complement isNoThrow, and changed hadDynamicExceptionSpec to take a parameter, e.g., isThrow() or isNoThrow().

[aaron.ballman]

I'm not keen on the new direction this patch has taken. hasDynamicExceptionSpec(isThrow()) is quite novel. What is the problem you are trying to solve with this?

include/clang/ASTMatchers/ASTMatchers.h

3251

I'm not comfortable with this matcher; users can use unless(isNoThrow()) to get this behavior already.

[hintonda]

Great, unless() was what I was missing. I'll refactor along those lines.

As for what I'm trying to achieve, I want a set containing "throw()" and another set containing "throw(something)". If there's a cleaner way to achieve that with an existing matcher, please let me know.

[aaron.ballman]

In D20052#430903, @hintonda wrote:

Great, unless() was what I was missing. I'll refactor along those lines.

As for what I'm trying to achieve, I want a set containing "throw()" and another set containing "throw(something)". If there's a cleaner way to achieve that with an existing matcher, please let me know.

allOf(hasDynamicExceptionSpecification(), isNoThrow()) gets you "throw()" and allOf(hasDynamicExceptionSpecification(), unless(isNoThrow()) gets you "throw(something)", doesn't it?

[hintonda]

Great, that's exactly what I needed. I'll revert back to the previous version.

[hintonda]

Revert back to previous version.

[aaron.ballman]

Okay, back to looking good. :-) I will commit on your behalf, since I'm back to somewhere with source access again.

[hintonda]

Great, thanks again. This has been a great learning experience.

[aaron.ballman]

Thank you for the work on this! I've commit in r269662

include/clang/ASTMatchers/ASTMatchers.h

 ///   class B { ~B() = default; };
 /// \endcode
 /// functionDecl(isDefaulted())
 ///   matches the declaration of ~B, but not ~A.
 AST_MATCHER(FunctionDecl, isDefaulted) {
   return Node.isDefaulted();
 }
 
+/// \brief Matches functions that have a dynamic exception specification.
+///
+/// Given:
+/// \code
+///   void f();
+///   void g() noexcept;
+///   void h() throw();
+///   void i() throw(int);
+///   void j() throw(...);
+///   void k() noexcept(false);
+/// \endcode
+/// functionDecl(hasDynamicExceptionSpec())
+///   matches the declarations of h, i, and j, but not f, g or k.
+AST_MATCHER(FunctionDecl, hasDynamicExceptionSpec) {
+  if (const auto *FnTy = Node.getType()->getAs<FunctionProtoType>())
+    return FnTy->hasDynamicExceptionSpec();
+  return false;
+}
+
 /// \brief Matches functions that have a non-throwing exception specification.
 ///
 /// Given:
 /// \code
 ///   void f();
 ///   void g() noexcept;
 ///   void h() throw();
 ///   void i() throw(int);
 ///   void j() noexcept(false);
 /// \endcode
 /// functionDecl(isNoThrow())
 ///   matches the declarations of g, and h, but not f, i or j.
 AST_MATCHER(FunctionDecl, isNoThrow) {
   const auto *FnTy = Node.getType()->getAs<FunctionProtoType>();
 
   // If the function does not have a prototype, then it is assumed to be a
   // throwing function (as it would if the function did not have any exception
   // specification).
   if (!FnTy)
     return false;
 
   // Assume the best for any unresolved exception specification.
   if (isUnresolvedExceptionSpec(FnTy->getExceptionSpecType()))
     return true;
 
   return FnTy->isNothrow(Node.getASTContext());