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| author | Richard Smith <richard-llvm@metafoo.co.uk> | 2012-02-08 06:14:53 +0000 |
|---|---|---|
| committer | Richard Smith <richard-llvm@metafoo.co.uk> | 2012-02-08 06:14:53 +0000 |
| commit | da7c4ba1af98430eb16468d2cf211473a3be175e (patch) | |
| tree | f42101a97dc688acefcbd411a1f0b8e50cbd9007 /clang/lib | |
| parent | 5bc1712940fb7b88aae6ba46766567c9c886a1f8 (diff) | |
| download | bcm5719-llvm-da7c4ba1af98430eb16468d2cf211473a3be175e.tar.gz bcm5719-llvm-da7c4ba1af98430eb16468d2cf211473a3be175e.zip | |
Implement the agreed resolution to DR1457: a signed left shift of a 1 bit into
the sign bit doesn't have undefined behavior, but a signed left shift of a 1 bit
out of the sign bit still does. As promised to Howard :)
The suppression of the potential constant expression checking in system headers
is also removed, since the problem it was working around is gone.
llvm-svn: 150059
Diffstat (limited to 'clang/lib')
| -rw-r--r-- | clang/lib/AST/ExprConstant.cpp | 7 | ||||
| -rw-r--r-- | clang/lib/Sema/SemaDeclCXX.cpp | 7 |
2 files changed, 4 insertions, 10 deletions
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index e33d22a4aa3..410406788dc 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -4704,12 +4704,11 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { << RHS << E->getType() << LHS.getBitWidth(); } else if (LHS.isSigned()) { // C++11 [expr.shift]p2: A signed left shift must have a non-negative - // operand, and must not overflow. + // operand, and must not overflow the corresponding unsigned type. if (LHS.isNegative()) CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; - else if (LHS.countLeadingZeros() <= SA) - HandleOverflow(Info, E, LHS.extend(LHS.getBitWidth() + SA) << SA, - E->getType()); + else if (LHS.countLeadingZeros() < SA) + CCEDiag(E, diag::note_constexpr_lshift_discards); } return Success(LHS << SA, E); diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp index 2c1642361b8..ca64af644f6 100644 --- a/clang/lib/Sema/SemaDeclCXX.cpp +++ b/clang/lib/Sema/SemaDeclCXX.cpp @@ -984,13 +984,8 @@ bool Sema::CheckConstexprFunctionBody(const FunctionDecl *Dcl, Stmt *Body, // C++11 [dcl.constexpr]p4: // - every constructor involved in initializing non-static data members and // base class sub-objects shall be a constexpr constructor. - // - // FIXME: We currently disable this check inside system headers, to work - // around early STL implementations which contain constexpr functions which - // can't produce constant expressions. llvm::SmallVector<PartialDiagnosticAt, 8> Diags; - if (!Context.getSourceManager().isInSystemHeader(Dcl->getLocation()) && - !IsInstantiation && !Expr::isPotentialConstantExpr(Dcl, Diags)) { + if (!IsInstantiation && !Expr::isPotentialConstantExpr(Dcl, Diags)) { Diag(Dcl->getLocation(), diag::err_constexpr_function_never_constant_expr) << isa<CXXConstructorDecl>(Dcl); for (size_t I = 0, N = Diags.size(); I != N; ++I) |
