Hi Richard, I am unsure if you are specifically the code owner of Sema, but can you please approve this change for the 3.8 branch?
-Dimitry > On 19 Jan 2016, at 04:58, Faisal Vali via cfe-commits > <cfe-commits@lists.llvm.org> wrote: > > Author: faisalv > Date: Mon Jan 18 21:58:55 2016 > New Revision: 258110 > > URL: http://llvm.org/viewvc/llvm-project?rev=258110&view=rev > Log: > Fix PR26134: When substituting into default template arguments, keep > CurContext unchanged. > > Or, do not set Sema's CurContext to the template declaration's when > substituting into default template arguments of said template declaration. > If we do push the template declaration context on to Sema, and the template > declaration is at namespace scope, Sema can get confused and try and do odr > analysis when substituting into default template arguments, even though the > substitution could be occurring within a dependent context. > I'm not sure why this was being done, perhaps there was concern that if a > default template argument referred to a previous template parameter, it might > not be found during substitution - but all regression tests pass, and I can't > craft a test that would cause it to fails (if some one does, please inform > me, and i'll craft a different fix for the PR). > > > This patch removes a single line of code, but unfortunately adds more than it > removes, because of the tests. Some day I still hope to commit a patch that > removes far more lines than it adds, while leaving clang better for it ;) > > Sorry that r253590 ("Change the expression evaluation context from > Unevaluated to ConstantEvaluated while substituting into non-type template > argument defaults") caused the PR! > > > > > > Modified: > cfe/trunk/lib/Sema/SemaTemplate.cpp > cfe/trunk/test/SemaTemplate/default-arguments.cpp > > Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=258110&r1=258109&r2=258110&view=diff > ============================================================================== > --- cfe/trunk/lib/Sema/SemaTemplate.cpp (original) > +++ cfe/trunk/lib/Sema/SemaTemplate.cpp Mon Jan 18 21:58:55 2016 > @@ -3281,7 +3281,6 @@ SubstDefaultTemplateArgument(Sema &SemaR > for (unsigned i = 0, e = Param->getDepth(); i != e; ++i) > TemplateArgLists.addOuterTemplateArguments(None); > > - Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext()); > EnterExpressionEvaluationContext ConstantEvaluated(SemaRef, > Sema::ConstantEvaluated); > return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists); > > Modified: cfe/trunk/test/SemaTemplate/default-arguments.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/default-arguments.cpp?rev=258110&r1=258109&r2=258110&view=diff > ============================================================================== > --- cfe/trunk/test/SemaTemplate/default-arguments.cpp (original) > +++ cfe/trunk/test/SemaTemplate/default-arguments.cpp Mon Jan 18 21:58:55 2016 > @@ -179,3 +179,31 @@ struct C { > C(T t = ); // expected-error {{expected expression}} > }; > C<int> obj; > + > +namespace PR26134 { > +// Make sure when substituting default template arguments we do it in the > current context. > +template<class T, bool Val = T::value> > +struct X {}; > + > +template<bool B> struct Y { > + void f() { X<Y> xy; } > + static const bool value = B; > +}; > + > +namespace ns1 { > +template<class T0> > +struct X { > + template<bool B = T0::value> struct XInner { static const bool value = B; > }; > +}; > +template<bool B> struct S { static const bool value = B; }; > +#if __cplusplus > 199711L > +template<bool B> struct Y { > + static constexpr bool f() { return typename X<S<B>>::template > XInner<>{}.value; } > + static_assert(f() == B, ""); > +}; > +Y<true> y; > +Y<false> y2; > +#endif > + > +} // end ns1 > +} // end ns PR26134 > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
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