aaron.ballman accepted this revision.
aaron.ballman added a comment.
This revision is now accepted and ready to land.
LGTM!
================
Comment at: lib/Sema/SemaTemplate.cpp:3055
+// Print a diagnostic for the failing static_assert expression. Defaults to
+// pretty-printing the expression.
----------------
courbet wrote:
> aaron.ballman wrote:
> > courbet wrote:
> > > aaron.ballman wrote:
> > > > Comment is a bit out of date as this is no longer specific to
> > > > `static_assert`.
> > > >
> > > > It looks like this may also change the behavior of enable_if diagnostic
> > > > reporting. Do you need to update any of those tests from this change?
> > > > If not, can you devise some tests for that case as well to show that
> > > > this isn't just a static_assert behavior? (Do a search for
> > > > `findFailedBooleanCondition` to find where the behavior has changed.)
> > > Nope, unfortunately the code that calls this is actually untested...
> > > I could not find a test that actually enters the:
> > > ```
> > > if (TypeAliasTemplateDecl *AliasTemplate =
> > > dyn_cast<TypeAliasTemplateDecl>(Template))
> > > ```
> > > in `Sema::CheckTemplateIdType`.
> > >
> > > I stopped at the following insanity:
> > >
> > > ```
> > > // RUN: %clang_cc1 -std=c++11 -verify %s
> > >
> > > template <typename T, typename U>
> > > struct is_same {
> > > enum { value = 0 };
> > > };
> > >
> > > template <typename T> struct is_same<T, T> {
> > > enum { value = 1 };
> > > };
> > >
> > > struct Dispatch {
> > > template <typename T> using SameAs = is_same<int, T>;
> > > };
> > >
> > > template <typename DispatchT>
> > > struct S {
> > > template <typename T> using same = typename DispatchT::template
> > > SameAs<T>;
> > >
> > > template <typename T>
> > > static void foo() __attribute__((enable_if(same<T>::value, "")));
> > >
> > > };
> > >
> > > void runFoo() {
> > > // S<Dispatch>::foo<int>();
> > > S<FailedDispatch>::foo<float>();
> > >
> > > }
> > > ```
> > >
> > > This one exercises the code up to `if (CanonType.isNull()) {`, but I'm
> > > not sure how to get a null type here.
> > >
> > How about this:
> > ```
> > namespace boost {
> > template<bool, typename = void> struct enable_if {};
> > template<typename T> struct enable_if<true, T> { typedef T type; };
> > }
> >
> > template<typename T> struct NonTemplateFunction {
> > typename boost::enable_if<sizeof(T) == 4, int>::type f();
> > };
> >
> > template <typename T>
> > struct Bobble {
> > using type = T;
> > };
> >
> > struct Frobble {
> > using type = char;
> > };
> > NonTemplateFunction<Bobble<typename Frobble::type>::type> NTFC;
> > ```
> > That should trigger the path in `Sema::CheckTypenameType()`, I believe.
> This triggers:
> ```
> else if (ClassTemplateDecl *ClassTemplate
> = dyn_cast<ClassTemplateDecl>(Template))
> ```
>
> Modifying it to:
> ```
> namespace boost {
> template<bool, typename = void> struct enable_if {};
> template<typename T> struct enable_if<true, T> { typedef T type; };
> }
>
> template<typename T> struct NonTemplateFunction {
> template <typename U> using toto = typename boost::enable_if<sizeof(U) ==
> 4, int>::type;
> toto<T> f();
> };
>
> template <typename T>
> struct Bobble {
> using type = T;
> };
>
> struct Frobble {
> using type = char;
> };
> NonTemplateFunction<Bobble<typename Frobble::type>::type> NTFC;
> ```
>
> triggers the same path as my previous example, but not the `IsNull()` test.
Aw crud, well, we tried.
Repository:
rC Clang
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D54903/new/
https://reviews.llvm.org/D54903
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