diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -14594,10 +14594,17 @@ S.Diag(OpLoc, diag::err_decrement_bool) << Op->getSourceRange(); return QualType(); } - // Increment of bool sets it to true, but is deprecated. - S.Diag(OpLoc, S.getLangOpts().CPlusPlus17 ? diag::ext_increment_bool - : diag::warn_increment_bool) - << Op->getSourceRange(); + + if (S.getLangOpts().CPlusPlus17) { + // Increment of bool sets it to true, but is deprecated. + S.Diag(OpLoc, diag::ext_increment_bool) << Op->getSourceRange(); + + // Ensure increment bool SFINAE-friendly. + if (S.isUnevaluatedContext() || S.isSFINAEContext()) + return QualType(); + } else { + S.Diag(OpLoc, diag::warn_increment_bool) << Op->getSourceRange(); + } } else if (S.getLangOpts().CPlusPlus && ResType->isEnumeralType()) { // Error on enum increments and decrements in C++ mode S.Diag(OpLoc, diag::err_increment_decrement_enum) << IsInc << ResType; diff --git a/clang/test/SemaCXX/bool-SFINAE-friendly.cpp b/clang/test/SemaCXX/bool-SFINAE-friendly.cpp new file mode 100644 --- /dev/null +++ b/clang/test/SemaCXX/bool-SFINAE-friendly.cpp @@ -0,0 +1,28 @@ +// RUN: %clang_cc1 %std_cxx98-14 -fsyntax-only -verify=precxx17 %s +// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify=expected %s +// RUN: %clang_cc1 %std_cxx20- -fsyntax-only -verify=cxx20 %s +// expected-no-diagnostics + +template auto f(T t) -> decltype(++t); // precxx17-warning {{incrementing expression of type bool is deprecated}} + +auto f(...) -> void; +void g() { f(true); } + +#if __cplusplus >= 202002L +template +concept can_increment = requires(T t) { + ++t; +}; + +template +void f() { + static_assert(requires(T t) { ++t; }); // cxx20-error {{static assertion failed due to requirement 'requires (bool t) { <>; }'}} +} + +int main() { + f(); // cxx20-note {{in instantiation of function template specialization 'f' requested here}} + static_assert(!can_increment); + + return 0; +} +#endif