================
@@ -0,0 +1,103 @@
+// RUN: %check_clang_tidy %s bugprone-exception-rethrow %t -- -- -fexceptions
+
+struct exception {};
+
+namespace std {
+ template <class T>
+ T&& move(T &x) {
+ return static_cast<T&&>(x);
+ }
+}
+
+void correct() {
+ try {
+ throw exception();
+ } catch(const exception &) {
+ throw;
+ }
+}
+
+void correct2() {
+ try {
+ throw exception();
+ } catch(const exception &e) {
+ try {
+ throw exception();
+ } catch(...) {}
+ }
+}
+
+void not_correct() {
+ try {
+ throw exception();
+ } catch(const exception &e) {
+ throw e;
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught
'exception' exception, remove the argument to throw the original exception
object [bugprone-exception-rethrow]
+ }
+}
+
+void not_correct2() {
+ try {
+ throw exception();
+ } catch(const exception &e) {
+ throw (e);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught
'exception' exception, remove the argument to throw the original exception
object [bugprone-exception-rethrow]
+ }
+}
+
+void not_correct3() {
+ try {
+ throw exception();
+ } catch(const exception &e) {
+ throw exception(e);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught
'exception' exception, remove the argument to throw the original exception
object [bugprone-exception-rethrow]
+ }
+}
+
+void not_correct4() {
+ try {
+ throw exception();
+ } catch(exception &e) {
+ throw std::move(e);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught
'exception' exception, remove the argument to throw the original exception
object [bugprone-exception-rethrow]
+ }
+}
+
+void not_correct5() {
+ try {
+ throw 5;
+ } catch(const int &e) {
+ throw e;
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught
'int' exception, remove the argument to throw the original exception object
[bugprone-exception-rethrow]
+ }
+}
+
+void rethrow_not_correct() {
+ throw;
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: empty 'throw' outside a catch
block with no operand triggers 'std::terminate()' [bugprone-exception-rethrow]
+}
+
+void rethrow_not_correct2() {
+ try {
+ throw;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: empty 'throw' outside a catch
block with no operand triggers 'std::terminate()' [bugprone-exception-rethrow]
+ } catch(...) {
+ }
+}
+
+void rethrow_correct() {
+ try {
+ throw 5;
+ } catch(...) {
+ throw;
+ }
+}
+
+void rethrow_in_lambda() {
+ try {
+ throw 5;
+ } catch(...) {
+ auto lambda = [] { throw; };
+// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: empty 'throw' outside a catch
block with no operand triggers 'std::terminate()' [bugprone-exception-rethrow]
----------------
isuckatcs wrote:
This is actually correct if the lambda is called inside the catch block, or not
called at all.
See the snippet below on [godbolt](https://godbolt.org/z/xPhx4Pfa4).
```c++
void rethrow_in_lambda() {
try {
throw 5;
} catch(...) {
auto lambda = [] { throw; };
lambda();
}
}
```
The issue only happens, if the lambda escapes the `catch` block.
See my original example on [godbolt](https://godbolt.org/z/Yxoxso3ra):
```c++
void foo() {
std::function<void()> fn;
try {
throw 1;
} catch (...) {
fn = [] { throw; }; // the lambda and the `throw` escape the catch block
}
fn();
}
```
I think besides using a lambda, the only other way this can happen is the one
below.
```c++
void rethrow_in_lambda() {
std::function<void()> fn;
try {
throw 1;
} catch (...) {
struct wrapper {
static void foo() { throw; };
};
fn = wrapper::foo;
}
fn();
}
```
I guess to be 100% accurate in detecting these cases, we need flow sensitive
analysis*, so I think we should just ignore them and mention it in the docs
too. Finding these `throw;` statements is something we already do with
`ASTMatcher`s, so ignoring them will work.
*the `throw;` escaping can happen in any nested function. E.g.:
```c++
#include <functional>
std::function<void()> fn;
void escape(std::function<void()> &ref) {
fn = ref;
}
void rethrow_in_lambda() {
try {
throw 1;
} catch (...) {
std::function<void()> lambda = [] { throw; };
escape(lambda);
}
}
int main() {
rethrow_in_lambda();
fn();
return 0;
}
```
https://github.com/llvm/llvm-project/pull/86448
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