[clang-tools-extra] 8f378ea - [clang-tidy] Add check 'bugprone-unsafe-to-allow-exceptions' (#176430)
via cfe-commits
cfe-commits at lists.llvm.org
Wed Feb 18 01:11:42 PST 2026
Author: Balázs Kéri
Date: 2026-02-18T10:11:38+01:00
New Revision: 8f378ea7e6fa31179266c69368be56a866b631e1
URL: https://github.com/llvm/llvm-project/commit/8f378ea7e6fa31179266c69368be56a866b631e1
DIFF: https://github.com/llvm/llvm-project/commit/8f378ea7e6fa31179266c69368be56a866b631e1.diff
LOG: [clang-tidy] Add check 'bugprone-unsafe-to-allow-exceptions' (#176430)
`ExceptionEscapeCheck` does not warn if a function is `noexcept(false)`
(may throw) but is one of the functions where throwing exceptions is
unsafe. This check can be used to find such cases.
Added:
clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.cpp
clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.h
clang-tools-extra/docs/clang-tidy/checks/bugprone/unsafe-to-allow-exceptions.rst
clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions-precpp17.cpp
clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions.cpp
Modified:
clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/bugprone/exception-escape.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
Removed:
################################################################################
diff --git a/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp b/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
index 4150442c25d61..310184037afbd 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
@@ -106,6 +106,7 @@
#include "UnintendedCharOstreamOutputCheck.h"
#include "UniquePtrArrayMismatchCheck.h"
#include "UnsafeFunctionsCheck.h"
+#include "UnsafeToAllowExceptionsCheck.h"
#include "UnusedLocalNonTrivialVariableCheck.h"
#include "UnusedRaiiCheck.h"
#include "UnusedReturnValueCheck.h"
@@ -308,6 +309,8 @@ class BugproneModule : public ClangTidyModule {
"bugprone-crtp-constructor-accessibility");
CheckFactories.registerCheck<UnsafeFunctionsCheck>(
"bugprone-unsafe-functions");
+ CheckFactories.registerCheck<UnsafeToAllowExceptionsCheck>(
+ "bugprone-unsafe-to-allow-exceptions");
CheckFactories.registerCheck<UnusedLocalNonTrivialVariableCheck>(
"bugprone-unused-local-non-trivial-variable");
CheckFactories.registerCheck<UnusedRaiiCheck>("bugprone-unused-raii");
diff --git a/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt b/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt
index db1256d91d311..96ad671d03b39 100644
--- a/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt
@@ -108,6 +108,7 @@ add_clang_library(clangTidyBugproneModule STATIC
UnhandledSelfAssignmentCheck.cpp
UniquePtrArrayMismatchCheck.cpp
UnsafeFunctionsCheck.cpp
+ UnsafeToAllowExceptionsCheck.cpp
UnusedLocalNonTrivialVariableCheck.cpp
UnusedRaiiCheck.cpp
UnusedReturnValueCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.cpp
new file mode 100644
index 0000000000000..f9a236aba4459
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.cpp
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "UnsafeToAllowExceptionsCheck.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+namespace {
+
+AST_MATCHER(FunctionDecl, isExplicitThrow) {
+ return isExplicitThrowExceptionSpec(Node.getExceptionSpecType()) &&
+ Node.getExceptionSpecSourceRange().isValid();
+}
+
+} // namespace
+
+UnsafeToAllowExceptionsCheck::UnsafeToAllowExceptionsCheck(
+ StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ CheckedSwapFunctions(utils::options::parseStringList(
+ Options.get("CheckedSwapFunctions", "swap;iter_swap;iter_move"))) {}
+
+void UnsafeToAllowExceptionsCheck::storeOptions(
+ ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, "CheckedSwapFunctions",
+ utils::options::serializeStringList(CheckedSwapFunctions));
+}
+
+void UnsafeToAllowExceptionsCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(
+ functionDecl(isDefinition(), isExplicitThrow(),
+ anyOf(cxxDestructorDecl(),
+ cxxConstructorDecl(isMoveConstructor()),
+ cxxMethodDecl(isMoveAssignmentOperator()),
+ allOf(hasAnyName(CheckedSwapFunctions),
+ unless(parameterCountIs(0))),
+ isMain()))
+ .bind("f"),
+ this);
+}
+
+void UnsafeToAllowExceptionsCheck::check(
+ const MatchFinder::MatchResult &Result) {
+ const auto *MatchedDecl = Result.Nodes.getNodeAs<FunctionDecl>("f");
+ assert(MatchedDecl);
+
+ diag(MatchedDecl->getLocation(),
+ "function %0 should not throw exceptions but "
+ "it is still marked as potentially throwing")
+ << MatchedDecl;
+}
+
+} // namespace clang::tidy::bugprone
diff --git a/clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.h b/clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.h
new file mode 100644
index 0000000000000..d91d48427ce4a
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/bugprone/UnsafeToAllowExceptionsCheck.h
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_UNSAFETOALLOWEXCEPTIONSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_UNSAFETOALLOWEXCEPTIONSCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::bugprone {
+
+/// Finds functions where throwing exceptions is unsafe but the function is
+/// still marked as potentially throwing.
+///
+/// For the user-facing documentation see:
+/// https://clang.llvm.org/extra/clang-tidy/checks/bugprone/unsafe-to-allow-exceptions.html
+class UnsafeToAllowExceptionsCheck : public ClangTidyCheck {
+public:
+ UnsafeToAllowExceptionsCheck(StringRef Name, ClangTidyContext *Context);
+ bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+ return LangOpts.CPlusPlus && LangOpts.CXXExceptions;
+ }
+ void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ std::vector<llvm::StringRef> CheckedSwapFunctions;
+};
+
+} // namespace clang::tidy::bugprone
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_UNSAFETOALLOWEXCEPTIONSCHECK_H
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 2bb4800df47c9..68bab88146241 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -102,6 +102,12 @@ Improvements to clang-tidy
New checks
^^^^^^^^^^
+- New :doc:`bugprone-unsafe-to-allow-exceptions
+ <clang-tidy/checks/bugprone/unsafe-to-allow-exceptions>` check.
+
+ Finds functions where throwing exceptions is unsafe but the function is still
+ marked as potentially throwing.
+
- New :doc:`llvm-type-switch-case-types
<clang-tidy/checks/llvm/type-switch-case-types>` check.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/bugprone/exception-escape.rst b/clang-tools-extra/docs/clang-tidy/checks/bugprone/exception-escape.rst
index a655661c57871..0a0c21f62c7a0 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/bugprone/exception-escape.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/bugprone/exception-escape.rst
@@ -28,7 +28,10 @@ Functions declared explicitly with ``noexcept(false)`` or ``throw(exception)``
will be excluded from the analysis, as even though it is not recommended for
functions like ``swap()``, ``main()``, move constructors, move assignment
operators and destructors, it is a clear indication of the developer's
-intention and should be respected.
+intention and should be respected. To check if these special functions are
+marked as potentially throwing, the check
+:doc:`bugprone-unsafe-to-allow-exceptions <unsafe-to-allow-exceptions>` can be
+used.
WARNING! This check may be expensive on large source files.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/bugprone/unsafe-to-allow-exceptions.rst b/clang-tools-extra/docs/clang-tidy/checks/bugprone/unsafe-to-allow-exceptions.rst
new file mode 100644
index 0000000000000..894b1415e83dd
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/bugprone/unsafe-to-allow-exceptions.rst
@@ -0,0 +1,41 @@
+.. title:: clang-tidy - bugprone-unsafe-to-allow-exceptions
+
+bugprone-unsafe-to-allow-exceptions
+===================================
+
+Finds functions where throwing exceptions is unsafe but the function is still
+marked as potentially throwing. Throwing exceptions from the following
+functions can be problematic:
+
+* Destructors
+* Move constructors
+* Move assignment operators
+* The ``main()`` functions
+* ``swap()`` functions
+* ``iter_swap()`` functions
+* ``iter_move()`` functions
+
+A destructor throwing an exception may result in undefined behavior, resource
+leaks or unexpected termination of the program. Throwing move constructor or
+move assignment also may result in undefined behavior or resource leak. The
+``swap()`` operations expected to be non throwing most of the cases and they
+are always possible to implement in a non throwing way. Non throwing ``swap()``
+operations are also used to create move operations. A throwing ``main()``
+function also results in unexpected termination.
+
+The check finds any of these functions if it is marked with ``noexcept(false)``
+or ``throw(exception)``. This would indicate that the function is expected to
+throw exceptions. Only the presence of these keywords is checked, not if the
+function actually throws any exception. To check if the function actually
+throws exception, the check :doc:`bugprone-exception-escape <exception-escape>`
+can be used (but it does not warn if a function is explicitly marked as
+throwing).
+
+Options
+-------
+
+.. option:: CheckedSwapFunctions
+
+ Semicolon-separated list of checked swap function names (where throwing
+ exceptions is unsafe). These functions are checked if the parameter count is
+ at least 1. Default value is `swap;iter_swap;iter_move`.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 0eabd9929dc39..c475870ed7b31 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -176,6 +176,7 @@ Clang-Tidy Checks
:doc:`bugprone-unintended-char-ostream-output <bugprone/unintended-char-ostream-output>`, "Yes"
:doc:`bugprone-unique-ptr-array-mismatch <bugprone/unique-ptr-array-mismatch>`, "Yes"
:doc:`bugprone-unsafe-functions <bugprone/unsafe-functions>`,
+ :doc:`bugprone-unsafe-to-allow-exceptions <bugprone/unsafe-to-allow-exceptions>`,
:doc:`bugprone-unused-local-non-trivial-variable <bugprone/unused-local-non-trivial-variable>`,
:doc:`bugprone-unused-raii <bugprone/unused-raii>`, "Yes"
:doc:`bugprone-unused-return-value <bugprone/unused-return-value>`,
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions-precpp17.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions-precpp17.cpp
new file mode 100644
index 0000000000000..4f36557743cbd
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions-precpp17.cpp
@@ -0,0 +1,49 @@
+// RUN: %check_clang_tidy -std=c++11,c++14 %s bugprone-unsafe-to-allow-exceptions %t -- \
+// RUN: -config="{CheckOptions: { \
+// RUN: bugprone-unsafe-to-allow-exceptions.CheckedSwapFunctions: 'swap', \
+// RUN: }}" \
+// RUN: -- -fexceptions
+
+class Exception {};
+
+struct may_throw {
+ may_throw(may_throw&&) throw(int) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'may_throw' should not throw exceptions but it is still marked as potentially throwing [bugprone-unsafe-to-allow-exceptions]
+ }
+ may_throw& operator=(may_throw&&) throw(Exception) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: function 'operator=' should not throw exceptions but it is still marked as potentially throwing
+ }
+ ~may_throw() throw(char, Exception) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function '~may_throw' should not throw exceptions but it is still marked as potentially throwing
+ }
+
+ void f() noexcept(false) {
+ }
+};
+
+struct no_throw {
+ no_throw(no_throw&&) throw() {
+ }
+ no_throw& operator=(no_throw&&) noexcept(true) {
+ }
+ ~no_throw() noexcept(true) {
+ }
+};
+
+int main() throw(char) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: function 'main' should not throw exceptions but it is still marked as potentially throwing
+ return 0;
+}
+
+void swap(no_throw&, no_throw&) throw(bool) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'swap' should not throw exceptions but it is still marked as potentially throwing
+}
+
+void iter_swap(int&, int&) throw(bool) {
+}
+
+void iter_move(int&) throw(bool) {
+}
+
+void swap(double&, double&) {
+}
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions.cpp
new file mode 100644
index 0000000000000..c6242881f295a
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unsafe-to-allow-exceptions.cpp
@@ -0,0 +1,54 @@
+// RUN: %check_clang_tidy -std=c++17-or-later %s bugprone-unsafe-to-allow-exceptions %t -- -- -fexceptions
+// RUN: %check_clang_tidy -std=c++17-or-later -check-suffix=,CUSTOMSWAP %s bugprone-unsafe-to-allow-exceptions %t -- \
+// RUN: -config="{CheckOptions: { \
+// RUN: bugprone-unsafe-to-allow-exceptions.CheckedSwapFunctions: 'swap;iter_swap;iter_move;swap1', \
+// RUN: }}" \
+// RUN: -- -fexceptions
+
+struct may_throw {
+ may_throw(may_throw&&) noexcept(false) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'may_throw' should not throw exceptions but it is still marked as potentially throwing [bugprone-unsafe-to-allow-exceptions]
+ }
+ may_throw& operator=(may_throw&&) noexcept(false) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: function 'operator=' should not throw exceptions but it is still marked as potentially throwing
+ }
+ ~may_throw() noexcept(false) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function '~may_throw' should not throw exceptions but it is still marked as potentially throwing
+ }
+
+ void f() noexcept(false) {
+ }
+};
+
+struct no_throw {
+ no_throw(no_throw&&) throw() {
+ }
+ no_throw& operator=(no_throw&&) noexcept(true) {
+ }
+ ~no_throw() noexcept(true) {
+ }
+};
+
+int main() noexcept(false) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: function 'main' should not throw exceptions but it is still marked as potentially throwing
+ return 0;
+}
+
+void swap(int&, int&) noexcept(false) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'swap' should not throw exceptions but it is still marked as potentially throwing
+}
+
+void iter_swap(int&, int&) noexcept(false) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'iter_swap' should not throw exceptions but it is still marked as potentially throwing
+}
+
+void iter_move(int&) noexcept(false) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'iter_move' should not throw exceptions but it is still marked as potentially throwing
+}
+
+void swap(double&, double&) {
+}
+
+void swap1(long&) noexcept(false) {
+ // CHECK-MESSAGES-CUSTOMSWAP: :[[@LINE-1]]:6: warning: function 'swap1' should not throw exceptions but it is still marked as potentially throwing
+}
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