From fdc2b1014aa0b2a2290aef78a2eced63021b4f9b Mon Sep 17 00:00:00 2001 From: Richard Smith Date: Wed, 25 May 2016 22:06:25 +0000 Subject: [PATCH] Fix rejects-valid on constexpr function that accesses a not-yet-defined 'extern const' variable. That variable might be defined as 'constexpr', so we cannot prove that a use of it could never be a constant expression. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@270774 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/AST/ExprConstant.cpp | 11 ++++++++--- test/SemaCXX/constant-expression-cxx11.cpp | 14 ++++++++++++++ 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp index 9b17db6f55..6c8a650967 100644 --- a/lib/AST/ExprConstant.cpp +++ b/lib/AST/ExprConstant.cpp @@ -2706,7 +2706,11 @@ static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, } } else { // FIXME: Allow folding of values of any literal type in all languages. - if (Info.getLangOpts().CPlusPlus11) { + if (Info.checkingPotentialConstantExpression() && + VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) { + // The definition of this variable could be constexpr. We can't + // access it right now, but may be able to in future. + } else if (Info.getLangOpts().CPlusPlus11) { Info.Diag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { @@ -5456,8 +5460,9 @@ bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { } auto *CXXRD = dyn_cast(RD); - Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0, - std::distance(RD->field_begin(), RD->field_end())); + if (Result.isUninit()) + Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0, + std::distance(RD->field_begin(), RD->field_end())); unsigned ElementNo = 0; bool Success = true; diff --git a/test/SemaCXX/constant-expression-cxx11.cpp b/test/SemaCXX/constant-expression-cxx11.cpp index 47606b4f03..a755f48048 100644 --- a/test/SemaCXX/constant-expression-cxx11.cpp +++ b/test/SemaCXX/constant-expression-cxx11.cpp @@ -1181,6 +1181,20 @@ namespace ExternConstexpr { constexpr int j = 0; constexpr int k; // expected-error {{default initialization of an object of const type}} } + + extern const int q; + constexpr int g() { return q; } + constexpr int q = g(); + static_assert(q == 0, "zero-initialization should precede static initialization"); + + extern int r; // expected-note {{here}} + constexpr int h() { return r; } // expected-error {{never produces a constant}} expected-note {{read of non-const}} + + struct S { int n; }; + extern const S s; + constexpr int x() { return s.n; } + constexpr S s = {x()}; + static_assert(s.n == 0, "zero-initialization should precede static initialization"); } namespace ComplexConstexpr { -- 2.40.0