From e0ca1f5e689d09f91f5de7bc37a9a588e0ad5a56 Mon Sep 17 00:00:00 2001 From: Victor Chernyakin Date: Wed, 24 Sep 2025 12:43:55 -0700 Subject: [PATCH 1/3] [clang-tidy] Improve `bugprone-exception-escape`'s handling of lambdas --- .../clang-tidy/utils/ExceptionAnalyzer.cpp | 5 +++ clang-tools-extra/docs/ReleaseNotes.rst | 5 +++ .../checkers/bugprone/exception-escape.cpp | 34 +++++++++++++++++++ 3 files changed, 44 insertions(+) diff --git a/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp b/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp index bdde7249d2796..fd4320eb8144b 100644 --- a/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp +++ b/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp @@ -595,6 +595,11 @@ ExceptionAnalyzer::throwsException(const Stmt *St, Results.merge(DestructorExcs); } } + } else if (const auto *Lambda = dyn_cast(St)) { + for (const Stmt *Init : Lambda->capture_inits()) { + ExceptionInfo Excs = throwsException(Init, Caught, CallStack); + Results.merge(Excs); + } } else { for (const Stmt *Child : St->children()) { ExceptionInfo Excs = throwsException(Child, Caught, CallStack); diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst index 7cdff86beeec6..63ea45cb39270 100644 --- a/clang-tools-extra/docs/ReleaseNotes.rst +++ b/clang-tools-extra/docs/ReleaseNotes.rst @@ -210,6 +210,11 @@ Changes in existing checks correcting a spelling mistake on its option ``NamePrefixSuffixSilenceDissimilarityTreshold``. +- Improved :doc:`bugprone-exception-escape + ` check's handling of lambdas: + exceptions from captures are now diagnosed, exceptions in the bodies of + lambdas that aren't actually invoked are not. + - Improved :doc:`bugprone-infinite-loop ` check by adding detection for variables introduced by structured bindings. diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp index b10bd1d482867..90022b96a3130 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp @@ -894,3 +894,37 @@ void pointer_exception_can_not_escape_with_void_handler() noexcept { } catch (void *) { } } + +void throw_in_uninvoked_lambda() noexcept { + [] { throw 42; }; +} + +void throw_in_lambda() noexcept { + // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: an exception may be thrown in function 'throw_in_lambda' which should not throw exceptions + [] { throw 42; }(); + // CHECK-MESSAGES: :[[@LINE-1]]:8: note: frame #0: unhandled exception of type 'int' may be thrown in function 'operator()' here + // CHECK-MESSAGES: :[[@LINE-2]]:19: note: frame #1: function 'throw_in_lambda' calls function 'operator()' here +} + +struct copy_constructor_throws { + copy_constructor_throws(const copy_constructor_throws&) { throw 42; } +}; + +void throw_in_lambda_default_by_value_capture(const copy_constructor_throws& a) noexcept { + // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: an exception may be thrown in function 'throw_in_lambda_default_by_value_capture' which should not throw exceptions + [=] { a; }; + // CHECK-MESSAGES: :[[@LINE-6]]:61: note: frame #0: unhandled exception of type 'int' may be thrown in function 'copy_constructor_throws' here + // CHECK-MESSAGES: :[[@LINE-2]]:4: note: frame #1: function 'throw_in_lambda_default_by_value_capture' calls function 'copy_constructor_throws' here +} + +void throw_in_lambda_explicit_by_value_capture(const copy_constructor_throws& a) noexcept { + // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: an exception may be thrown in function 'throw_in_lambda_explicit_by_value_capture' which should not throw exceptions + [a] {}; + // CHECK-MESSAGES: :[[@LINE-13]]:61: note: frame #0: unhandled exception of type 'int' may be thrown in function 'copy_constructor_throws' here + // CHECK-MESSAGES: :[[@LINE-2]]:4: note: frame #1: function 'throw_in_lambda_explicit_by_value_capture' calls function 'copy_constructor_throws' here +} + +void no_throw_in_lambda_by_reference_capture(const copy_constructor_throws& a) noexcept { + [&] { a; }; + [&a] {}; +} From 5cf9561ced5c2c8de360a85dd73aad42bf43f873 Mon Sep 17 00:00:00 2001 From: Victor Chernyakin Date: Wed, 24 Sep 2025 13:34:39 -0700 Subject: [PATCH 2/3] test throw in lambda --- .../test/clang-tidy/checkers/bugprone/exception-escape.cpp | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp index 90022b96a3130..e27148f81fcdd 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp @@ -928,3 +928,7 @@ void no_throw_in_lambda_by_reference_capture(const copy_constructor_throws& a) n [&] { a; }; [&a] {}; } + +const auto throw_in_noexcept_lambda = [] () noexcept { throw 42; }; +// CHECK-MESSAGES: :[[@LINE-1]]:39: warning: an exception may be thrown in function 'operator()' which should not throw exceptions +// CHECK-MESSAGES: :[[@LINE-2]]:56: note: frame #0: unhandled exception of type 'int' may be thrown in function 'operator()' here From 76518363feaaa526b7bc33b75af041498d5b0fd1 Mon Sep 17 00:00:00 2001 From: Victor Chernyakin Date: Thu, 25 Sep 2025 08:35:47 -0700 Subject: [PATCH 3/3] more tests --- .../checkers/bugprone/exception-escape.cpp | 24 +++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp index e27148f81fcdd..a52bbe2246d1e 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape.cpp @@ -929,6 +929,30 @@ void no_throw_in_lambda_by_reference_capture(const copy_constructor_throws& a) n [&a] {}; } +void throw_in_lambda_init_capture() noexcept { + // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: an exception may be thrown in function 'throw_in_lambda_init_capture' which should not throw exceptions + [a = [] { throw 42; return 0; }()] {}; + // CHECK-MESSAGES: :[[@LINE-1]]:13: note: frame #0: unhandled exception of type 'int' may be thrown in function 'operator()' here + // CHECK-MESSAGES: :[[@LINE-2]]:34: note: frame #1: function 'throw_in_lambda_init_capture' calls function 'operator()' here +} + +void throw_from_nested_lambda() noexcept { + // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: an exception may be thrown in function 'throw_from_nested_lambda' which should not throw exceptions + [] { [] { throw 42; }(); }(); + // CHECK-MESSAGES: :[[@LINE-1]]:13: note: frame #0: unhandled exception of type 'int' may be thrown in function 'operator()' here + // CHECK-MESSAGES: :[[@LINE-2]]:24: note: frame #1: function 'operator()' calls function 'operator()' here + // CHECK-MESSAGES: :[[@LINE-3]]:29: note: frame #2: function 'throw_from_nested_lambda' calls function 'operator()' here +} + const auto throw_in_noexcept_lambda = [] () noexcept { throw 42; }; // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: an exception may be thrown in function 'operator()' which should not throw exceptions // CHECK-MESSAGES: :[[@LINE-2]]:56: note: frame #0: unhandled exception of type 'int' may be thrown in function 'operator()' here + +void thrower() { + throw 42; +} + +const auto indirect_throw_in_noexcept_lambda = [] () noexcept { thrower(); }; +// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: an exception may be thrown in function 'operator()' which should not throw exceptions +// CHECK-MESSAGES: :[[@LINE-5]]:3: note: frame #0: unhandled exception of type 'int' may be thrown in function 'thrower' here +// CHECK-MESSAGES: :[[@LINE-3]]:65: note: frame #1: function 'operator()' calls function 'thrower' here