From cf7d2256d6b226421fced739b13ec1b380eb1fd5 Mon Sep 17 00:00:00 2001 From: David Bolvansky Date: Tue, 2 Oct 2018 06:02:30 +0000 Subject: Added warning for unary minus used with unsigned type Summary: Inspired by MSVC, which found some occurrences of this expression on our code base. Fixes PR38950 Reviewers: rsmith, craig.topper, spatel, RKSimon, aaron.ballman, thakis Reviewed By: rsmith Subscribers: joerg, Quuxplusone, lebedev.ri, craig.topper, RKSimon, cfe-commits Differential Revision: https://reviews.llvm.org/D52137 llvm-svn: 343560 --- clang/lib/Sema/SemaChecking.cpp | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'clang/lib/Sema/SemaChecking.cpp') diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index a258d349c68..d6183dde95f 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -10896,6 +10896,19 @@ CheckImplicitConversion(Sema &S, Expr *E, QualType T, SourceLocation CC, return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision); } + if (TargetRange.Width > SourceRange.Width) { + if (auto *UO = dyn_cast(E)) + if (UO->getOpcode() == UO_Minus) + if (Source->isUnsignedIntegerType()) { + if (Target->isUnsignedIntegerType()) + return DiagnoseImpCast(S, E, T, CC, + diag::warn_impcast_high_order_zero_bits); + if (Target->isSignedIntegerType()) + return DiagnoseImpCast(S, E, T, CC, + diag::warn_impcast_nonnegative_result); + } + } + if (TargetRange.Width == SourceRange.Width && !TargetRange.NonNegative && SourceRange.NonNegative && Source->isSignedIntegerType()) { // Warn when doing a signed to signed conversion, warn if the positive -- cgit v1.2.3