Author: Yaxun (Sam) Liu Date: 2023-02-21T12:43:42-05:00 New Revision: 8cda128c1eff8556505ff27117a68ad8cecaa228
URL: https://github.com/llvm/llvm-project/commit/8cda128c1eff8556505ff27117a68ad8cecaa228 DIFF: https://github.com/llvm/llvm-project/commit/8cda128c1eff8556505ff27117a68ad8cecaa228.diff LOG: [clang]Fix warning for signed conversion on LP64 Currently clang emits warning with -Wconversion for the following code on LP64 system e.g. x86_64-unknown-linux-gnu: long foo(long x) { return 1LL<<x; } warning: implicit conversion changes signedness: 'long long' to 'long' [-Wsign-conversion] return 1ll << x; ~~~~~~ ~~~~^~~~ This does not make sense since all operands are signed. This patch fixes that to match -m32 and GCC behaviour. Reviewed by: Fangrui Song Differential Revision: https://reviews.llvm.org/D144011 Added: Modified: clang/lib/Sema/SemaChecking.cpp clang/test/Sema/sign-conversion.c Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index 9d5490a99310f..eded6061c77eb 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -14316,6 +14316,12 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T, if (S.SourceMgr.isInSystemMacro(CC)) return; + if (SourceBT && SourceBT->isInteger() && TargetBT && + TargetBT->isInteger() && + Source->isSignedIntegerType() == Target->isSignedIntegerType()) { + return; + } + unsigned DiagID = diag::warn_impcast_integer_sign; // Traditionally, gcc has warned about this under -Wsign-compare. diff --git a/clang/test/Sema/sign-conversion.c b/clang/test/Sema/sign-conversion.c index 4b1ee7542158d..e96ab18a46ed0 100644 --- a/clang/test/Sema/sign-conversion.c +++ b/clang/test/Sema/sign-conversion.c @@ -1,8 +1,14 @@ // RUN: %clang_cc1 -fsyntax-only -verify -Wsign-conversion %s +// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fsyntax-only -verify -Wsign-conversion %s +// RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -fsyntax-only -verify -Wsign-conversion %s // PR9345: make a subgroup of -Wconversion for signedness changes void test(int x) { unsigned t0 = x; // expected-warning {{implicit conversion changes signedness}} unsigned t1 = (t0 == 5 ? x : 0); // expected-warning {{operand of ? changes signedness}} + + // Clang has special treatment for left shift of literal '1'. + // Make sure there is no diagnostics. + long t2 = 1LL << x; } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
