aaron.ballman added a comment. In D144285#4135807 <https://reviews.llvm.org/D144285#4135807>, @erichkeane wrote:
> In D144285#4135775 <https://reviews.llvm.org/D144285#4135775>, @Endill wrote: > >> Thank you for the patch. >> Any plans to backport this to 16.x branch? > > I would not really want us to do that, the breaking change here is > concerning, and I'd like this to spend time in trunk 'baking' a while. +1, at this point the only things we should be backporting to 16.x are fixes for regressions or fixes for security concerns. ================ Comment at: clang/lib/Sema/SemaDeclCXX.cpp:16824-16841 if (InnerCond && isa<ConceptSpecializationExpr>(InnerCond)) { // Drill down into concept specialization expressions to see why they // weren't satisfied. Diag(StaticAssertLoc, diag::err_static_assert_failed) << !AssertMessage << Msg.str() << AssertExpr->getSourceRange(); ConstraintSatisfaction Satisfaction; if (!CheckConstraintSatisfaction(InnerCond, Satisfaction)) ---------------- cor3ntin wrote: > rsmith wrote: > > I wonder if it's worth adding a custom diagnostic (eg, "this template > > cannot be instantiated: %0") for the case where we're in template > > instantiation and the expression is the bool literal `false`. > I'm not sure i see the motivation. Why would we want to special case `false`? > The expression could also be an always false, never dependent expression Richard may have different ideas in mind, but the motivation to me is code like: ``` template <typename Ty> struct S { static_assert(false, "you have to use one of the valid specializations, not the primary template"); }; template <> struct S<int> { }; template <> struct S<float> { }; int main() { S<int> s1; S<float> s2; S<double> s3; } ``` Rather than telling the user the static_assert failed because false is not true, having a custom diagnostic might read better for users. GCC doesn't produce a custom diagnostic -- the behavior isn't terrible, but the "false evaluates to false" note is effectively just noise, too: https://godbolt.org/z/456bzWG7c Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D144285/new/ https://reviews.llvm.org/D144285 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
