[clang-tools-extra] [clang-tidy] Add AllowLogicalOperatorConversion option to implicit-bool-conversion (PR #189149)
Baranov Victor via cfe-commits
cfe-commits at lists.llvm.org
Sat Mar 28 01:12:16 PDT 2026
https://github.com/vbvictor created https://github.com/llvm/llvm-project/pull/189149
Fixes https://github.com/llvm/llvm-project/issues/176889.
>From b60f86e3185addc896fe8de02825c09cd0c34a13 Mon Sep 17 00:00:00 2001
From: Victor Baranov <bar.victor.2002 at gmail.com>
Date: Sat, 28 Mar 2026 11:12:01 +0300
Subject: [PATCH] [clang-tidy] Add AllowLogicalOperatorConversion option to
implicit-bool-conversion
---
.../ImplicitBoolConversionCheck.cpp | 19 ++++
.../readability/ImplicitBoolConversionCheck.h | 1 +
clang-tools-extra/docs/ReleaseNotes.rst | 6 ++
.../readability/implicit-bool-conversion.rst | 7 ++
...-bool-conversion-allow-logical-operators.c | 94 +++++++++++++++++++
5 files changed, 127 insertions(+)
create mode 100644 clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion-allow-logical-operators.c
diff --git a/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp b/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
index a138d1900b799..31081f2f93dc2 100644
--- a/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
@@ -245,11 +245,22 @@ static bool isCastAllowedInCondition(const ImplicitCastExpr *Cast,
return false;
}
+static bool isLogicalOperatorResult(const ImplicitCastExpr *Cast) {
+ const Expr *SubExpr = Cast->getSubExpr()->IgnoreParenImpCasts();
+ if (const auto *BinOp = dyn_cast<BinaryOperator>(SubExpr))
+ return BinOp->isLogicalOp();
+ if (const auto *UnOp = dyn_cast<UnaryOperator>(SubExpr))
+ return UnOp->getOpcode() == UO_LNot;
+ return false;
+}
+
ImplicitBoolConversionCheck::ImplicitBoolConversionCheck(
StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
AllowIntegerConditions(Options.get("AllowIntegerConditions", false)),
AllowPointerConditions(Options.get("AllowPointerConditions", false)),
+ AllowLogicalOperatorConversion(
+ Options.get("AllowLogicalOperatorConversion", false)),
UseUpperCaseLiteralSuffix(
Options.get("UseUpperCaseLiteralSuffix", false)) {}
@@ -257,6 +268,8 @@ void ImplicitBoolConversionCheck::storeOptions(
ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "AllowIntegerConditions", AllowIntegerConditions);
Options.store(Opts, "AllowPointerConditions", AllowPointerConditions);
+ Options.store(Opts, "AllowLogicalOperatorConversion",
+ AllowLogicalOperatorConversion);
Options.store(Opts, "UseUpperCaseLiteralSuffix", UseUpperCaseLiteralSuffix);
}
@@ -382,6 +395,12 @@ void ImplicitBoolConversionCheck::handleCastToBool(const ImplicitCastExpr *Cast,
return;
}
+ if (AllowLogicalOperatorConversion &&
+ Cast->getCastKind() == CK_IntegralToBoolean &&
+ isLogicalOperatorResult(Cast)) {
+ return;
+ }
+
auto Diag = diag(Cast->getBeginLoc(), "implicit conversion %0 -> 'bool'")
<< Cast->getSubExpr()->getType();
diff --git a/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.h b/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.h
index 6ae15a9e19fe2..add4b97c7bdfe 100644
--- a/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.h
+++ b/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.h
@@ -36,6 +36,7 @@ class ImplicitBoolConversionCheck : public ClangTidyCheck {
const bool AllowIntegerConditions;
const bool AllowPointerConditions;
+ const bool AllowLogicalOperatorConversion;
const bool UseUpperCaseLiteralSuffix;
};
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index f8550e72dcc85..91e2b65d3ed12 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -402,6 +402,12 @@ Changes in existing checks
temporaries (e.g. passing a string literal to a ``const std::string&``
parameter)
+- Improved :doc:`readability-implicit-bool-conversion
+ <clang-tidy/checks/readability/implicit-bool-conversion>` check by adding
+ `AllowLogicalOperatorConversion` option to suppress warnings on implicit
+ conversions of logical operator results (``&&``, ``||``, ``!``) to ``bool``
+ in C.
+
- Improved :doc:`readability-non-const-parameter
<clang-tidy/checks/readability/non-const-parameter>` check by avoiding false
positives on parameters used in dependent expressions (e.g. inside generic
diff --git a/clang-tools-extra/docs/clang-tidy/checks/readability/implicit-bool-conversion.rst b/clang-tools-extra/docs/clang-tidy/checks/readability/implicit-bool-conversion.rst
index 66e2fd0beaea1..efa30ae8a4649 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/readability/implicit-bool-conversion.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/readability/implicit-bool-conversion.rst
@@ -139,6 +139,13 @@ Options
When `true`, the check will allow conditional pointer conversions. Default
is `false`.
+.. option:: AllowLogicalOperatorConversion
+
+ When `true`, the check will suppress warnings for implicit conversions of
+ logical operator results (``&&``, ``||``, ``!``) to ``bool``. These
+ operators always produce values equal to ``0`` or ``1``, so the conversion
+ is safe. Default is `false`.
+
.. option:: UseUpperCaseLiteralSuffix
When `true`, the replacements will use an uppercase literal suffix in the
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion-allow-logical-operators.c b/clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion-allow-logical-operators.c
new file mode 100644
index 0000000000000..4b4a8e8de76da
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion-allow-logical-operators.c
@@ -0,0 +1,94 @@
+// RUN: %check_clang_tidy -std=c23-or-later %s readability-implicit-bool-conversion %t -- \
+// RUN: -config='{CheckOptions: { \
+// RUN: readability-implicit-bool-conversion.AllowLogicalOperatorConversion: true \
+// RUN: }}'
+
+void function_taking_bool(bool);
+bool returns_bool(void);
+int returns_int(void);
+
+void logical_or_to_bool(void) {
+ bool a = true, b = false;
+ bool c = a || b;
+ bool d = returns_bool() || returns_bool();
+ bool e = returns_bool() || (a && b);
+}
+
+void logical_and_to_bool(void) {
+ bool a = true, b = false;
+ bool c = a && b;
+ bool d = returns_bool() && returns_bool();
+}
+
+void logical_not_to_bool(void) {
+ bool a = true;
+ int x = 5;
+ bool b = !a;
+ bool c = !x;
+}
+
+void logical_with_literals(void) {
+ bool a = true, b = false;
+ bool c = true || b;
+ bool d = false || b;
+ bool e = a || true;
+ bool f = false || (a || b);
+}
+
+void nested_logical_ops(void) {
+ bool a = true, b = false, c = true;
+ bool d = (a && b) || c;
+ bool e = a || (b && c);
+ bool f = !(a || b);
+}
+
+void logical_in_function_call(void) {
+ bool a = true, b = false;
+ function_taking_bool(a || b);
+ function_taking_bool(a && b);
+ function_taking_bool(!a);
+}
+
+bool logical_in_return(void) {
+ bool a = true, b = false;
+ return a || b;
+}
+
+void still_warn_on_regular_int_to_bool(void) {
+ int x = 42;
+ bool b = x;
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: implicit conversion 'int' -> 'bool' [readability-implicit-bool-conversion]
+ // CHECK-FIXES: bool b = x != 0;
+
+ bool c = x + 1;
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: implicit conversion 'int' -> 'bool'
+ // CHECK-FIXES: bool c = (x + 1) != 0;
+
+ bool d = returns_int();
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: implicit conversion 'int' -> 'bool'
+ // CHECK-FIXES: bool d = returns_int() != 0;
+}
+
+void still_warn_on_bitwise_ops(void) {
+ int x = 5, y = 3;
+ bool b = x | y;
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: implicit conversion 'int' -> 'bool'
+ // CHECK-FIXES: bool b = (x | y) != 0;
+
+ bool c = x & y;
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: implicit conversion 'int' -> 'bool'
+ // CHECK-FIXES: bool c = (x & y) != 0;
+}
+
+void cast_from_bool_still_warns(void) {
+ bool a = true;
+ int x = a;
+ // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: implicit conversion 'bool' -> 'int'
+ // CHECK-FIXES: int x = (int)a;
+}
+
+void comparison_still_excluded(void) {
+ bool b1 = 1 > 0;
+ bool b2 = 1 == 0;
+ bool b3 = 1 < 2;
+}
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