Author: Oleksandr T. Date: 2025-03-07T01:05:56+02:00 New Revision: 93f0f3d33be596321730e9194cf24a73a75ce702
URL: https://github.com/llvm/llvm-project/commit/93f0f3d33be596321730e9194cf24a73a75ce702 DIFF: https://github.com/llvm/llvm-project/commit/93f0f3d33be596321730e9194cf24a73a75ce702.diff LOG: [Clang] add -Wshift-bool warning to handle shifting of bool (#127336) Fixes #28334 --- This PR introduces the `-Wshift-bool` warning to detect and warn against shifting `bool` values using the `>>` operator. Shifting a `bool` implicitly converts it to an `int`, which can lead to unintended behavior. Added: clang/test/Sema/shift-bool.cpp Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/Sema/SemaExpr.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 38b5bdf1dd46b..e1a8dad87ad29 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -222,6 +222,7 @@ Improvements to Clang's diagnostics under the subgroup ``-Wunsafe-buffer-usage-in-libc-call``. - Diagnostics on chained comparisons (``a < b < c``) are now an error by default. This can be disabled with ``-Wno-error=parentheses``. +- The ``-Wshift-bool`` warning has been added to warn about shifting a boolean. (#GH28334) - The :doc:`ThreadSafetyAnalysis` now supports ``-Wthread-safety-pointer``, which enables warning on passing or returning pointers to guarded variables diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 5e73c357a8124..cf0e9846d4259 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -7132,6 +7132,9 @@ def warn_shift_result_sets_sign_bit : Warning< "signed shift result (%0) sets the sign bit of the shift expression's " "type (%1) and becomes negative">, InGroup<DiagGroup<"shift-sign-overflow">>, DefaultIgnore; +def warn_shift_bool : Warning< + "right shifting a 'bool' implicitly converts it to 'int'">, + InGroup<DiagGroup<"shift-bool">>, DefaultIgnore; def warn_precedence_bitwise_rel : Warning< "%0 has lower precedence than %1; %1 will be evaluated first">, diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 7904ba966b38d..f896ccab53a54 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -11247,6 +11247,10 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS, if (S.getLangOpts().OpenCL) return; + if (Opc == BO_Shr && + LHS.get()->IgnoreParenImpCasts()->getType()->isBooleanType()) + S.Diag(Loc, diag::warn_shift_bool) << LHS.get()->getSourceRange(); + // Check right/shifter operand Expr::EvalResult RHSResult; if (RHS.get()->isValueDependent() || diff --git a/clang/test/Sema/shift-bool.cpp b/clang/test/Sema/shift-bool.cpp new file mode 100644 index 0000000000000..a17a0e0ad9e7d --- /dev/null +++ b/clang/test/Sema/shift-bool.cpp @@ -0,0 +1,25 @@ +// RUN: %clang_cc1 -fsyntax-only -Wshift-bool -verify %s + +void t() { + int x = 10; + bool y = true; + + bool a = y << x; + bool b = y >> x; // expected-warning {{right shifting a 'bool' implicitly converts it to 'int'}} + + bool c = false << x; + bool d = false >> x; // expected-warning {{right shifting a 'bool' implicitly converts it to 'int'}} + + bool e = y << 1; + bool f = y >> 1; // expected-warning {{right shifting a 'bool' implicitly converts it to 'int'}} + + bool g = y << -1; // expected-warning {{shift count is negative}} + bool h = y >> -1; // expected-warning {{right shifting a 'bool' implicitly converts it to 'int'}} \ + // expected-warning {{shift count is negative}} + + bool i = y << 0; + bool j = y >> 0; // expected-warning {{right shifting a 'bool' implicitly converts it to 'int'}} + + if ((y << 1) != 0) { } + if ((y >> 1) != 0) { } // expected-warning {{right shifting a 'bool' implicitly converts it to 'int'}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
