We should check VD->getInit()->isValueDependent() before we call evaluateValue. I wasn't able to come up with a test case that triggers the assert though :(
On Thu, Oct 19, 2017 at 5:45 PM, Alexander Kornienko <ale...@google.com> wrote: > > > On Sat, Oct 14, 2017 at 5:59 PM, Benjamin Kramer via cfe-commits > <cfe-commits@lists.llvm.org> wrote: >> >> Author: d0k >> Date: Sat Oct 14 08:59:34 2017 >> New Revision: 315811 >> >> URL: http://llvm.org/viewvc/llvm-project?rev=315811&view=rev >> Log: >> Re-land r315787, "[Sema] Warn about unused variables if we can constant >> evaluate the initializer." >> >> The warnings in libc++ tests were fixed in the meantime. >> >> Modified: >> cfe/trunk/lib/Sema/SemaDecl.cpp >> cfe/trunk/test/SemaCXX/warn-unused-variables.cpp >> >> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=315811&r1=315810&r2=315811&view=diff >> >> ============================================================================== >> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original) >> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Sat Oct 14 08:59:34 2017 >> @@ -1723,7 +1723,8 @@ static bool ShouldDiagnoseUnusedDecl(con >> dyn_cast<CXXConstructExpr>(Init); >> if (Construct && !Construct->isElidable()) { >> CXXConstructorDecl *CD = Construct->getConstructor(); >> - if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>()) >> + if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() && >> + !VD->evaluateValue()) > > > The evaluateValue call above causes an assertion failure on > instantiation-dependent values: > llvm/tools/clang/lib/AST/Decl.cpp:2196 in clang::APValue > *clang::VarDecl::evaluateValue(SmallVectorImpl<clang::PartialDiagnosticAt> > &) const: !Init->isValueDependent() > > I'm not sure why evaluateValue uses an assertion instead of outputting a > note and returning nullptr, but the assertion can be avoided on the caller > site as well. > > Working on a reduced test case... > >> >> return false; >> } >> } >> >> Modified: cfe/trunk/test/SemaCXX/warn-unused-variables.cpp >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-unused-variables.cpp?rev=315811&r1=315810&r2=315811&view=diff >> >> ============================================================================== >> --- cfe/trunk/test/SemaCXX/warn-unused-variables.cpp (original) >> +++ cfe/trunk/test/SemaCXX/warn-unused-variables.cpp Sat Oct 14 08:59:34 >> 2017 >> @@ -1,4 +1,5 @@ >> // RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label >> -Wno-c++1y-extensions -verify %s >> +// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label >> -Wno-c++1y-extensions -verify -std=c++11 %s >> template<typename T> void f() { >> T t; >> t = 17; >> @@ -194,3 +195,35 @@ void test() { >> } >> >> } >> + >> +#if __cplusplus >= 201103L >> +namespace with_constexpr { >> +template <typename T> >> +struct Literal { >> + T i; >> + Literal() = default; >> + constexpr Literal(T i) : i(i) {} >> +}; >> + >> +struct NoLiteral { >> + int i; >> + NoLiteral() = default; >> + constexpr NoLiteral(int i) : i(i) {} >> + ~NoLiteral() {} >> +}; >> + >> +static Literal<int> gl1; // expected-warning {{unused variable >> 'gl1'}} >> +static Literal<int> gl2(1); // expected-warning {{unused variable >> 'gl2'}} >> +static const Literal<int> gl3(0); // expected-warning {{unused variable >> 'gl3'}} >> + >> +template <typename T> >> +void test(int i) { >> + Literal<int> l1; // expected-warning {{unused variable 'l1'}} >> + Literal<int> l2(42); // expected-warning {{unused variable 'l2'}} >> + Literal<int> l3(i); // no-warning >> + Literal<T> l4(0); // no-warning >> + NoLiteral nl1; // no-warning >> + NoLiteral nl2(42); // no-warning >> +} >> +} >> +#endif >> >> >> _______________________________________________ >> cfe-commits mailing list >> cfe-commits@lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > > _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits