Merge pull request #497 from github/lcartey/exceptions-exclude-noexcept

Exceptions: do not rethrow from functions with incompatible exception specifications.

Author: rvermeulen

change_notes/2024-01-24-throwing-functions-exclude-noexcept.md

@@ -0,0 +1,6 @@
+ * Exceptions are no longer propagated from calls to `noexcept` functions, or calls functions with dynamic exception specifications where the exception is not permitted. This is consistent with the default behaviour specified in `[expect.spec]` which indicates that `std::terminate` is called. This has the following impact:
+   - `A15-4-2`, `ERR55-CPP` - reduce false positives for `noexcept` functions which call other `noexcept` function which may throw.
+   - `A15-2-2` - reduce false positives for constructors which call `noexcept` functions.
+   - `A15-4-5` - reduce false positives for checked exceptions that are thrown from `noexcept` functions called by the original function.
+   - `DCL57-CPP` - do not report exceptions thrown from `noexcept` functions called by deallocation functions or destructors.
+   - `A15-5-1`, `M15-3-1` - do not report exceptions thrown from `noexcept` functions called by special functions.

cpp/autosar/test/rules/A15-4-2/NoExceptFunctionThrows.expected

@@ -1,11 +1,19 @@
 edges
 | test.cpp:5:3:5:20 | throw ... [ExceptionA] | test.cpp:4:6:4:15 | test_throw [ExceptionA] |
-| test.cpp:8:6:8:11 | throwA [ExceptionA] | test.cpp:11:3:11:8 | call to throwA [ExceptionA] |
-| test.cpp:8:6:8:11 | throwA [ExceptionA] | test.cpp:15:3:15:8 | call to throwA [ExceptionA] |
+| test.cpp:8:6:8:11 | throwA [ExceptionA] | test.cpp:9:25:9:30 | call to throwA [ExceptionA] |
+| test.cpp:8:6:8:11 | throwA [ExceptionA] | test.cpp:10:42:10:47 | call to throwA [ExceptionA] |
+| test.cpp:8:6:8:11 | throwA [ExceptionA] | test.cpp:13:3:13:8 | call to throwA [ExceptionA] |
+| test.cpp:8:6:8:11 | throwA [ExceptionA] | test.cpp:17:3:17:8 | call to throwA [ExceptionA] |
 | test.cpp:8:17:8:34 | throw ... [ExceptionA] | test.cpp:8:6:8:11 | throwA [ExceptionA] |
-| test.cpp:11:3:11:8 | call to throwA [ExceptionA] | test.cpp:10:6:10:24 | test_indirect_throw [ExceptionA] |
-| test.cpp:15:3:15:8 | call to throwA [ExceptionA] | test.cpp:14:6:14:26 | test_indirect_throw_2 [ExceptionA] |
+| test.cpp:9:6:9:19 | indirectThrowA [ExceptionA] | test.cpp:34:3:34:16 | call to indirectThrowA [ExceptionA] |
+| test.cpp:9:25:9:30 | call to throwA [ExceptionA] | test.cpp:9:6:9:19 | indirectThrowA [ExceptionA] |
+| test.cpp:10:42:10:47 | call to throwA [ExceptionA] | test.cpp:10:6:10:27 | noexceptIndirectThrowA [ExceptionA] |
+| test.cpp:13:3:13:8 | call to throwA [ExceptionA] | test.cpp:12:6:12:24 | test_indirect_throw [ExceptionA] |
+| test.cpp:17:3:17:8 | call to throwA [ExceptionA] | test.cpp:16:6:16:26 | test_indirect_throw_2 [ExceptionA] |
+| test.cpp:34:3:34:16 | call to indirectThrowA [ExceptionA] | test.cpp:33:6:33:26 | test_indirect_throw_6 [ExceptionA] |
 #select
 | test.cpp:4:6:4:15 | test_throw | test.cpp:5:3:5:20 | throw ... [ExceptionA] | test.cpp:4:6:4:15 | test_throw [ExceptionA] | Function test_throw is declared noexcept(true) but can throw exceptions of type ExceptionA. |
-| test.cpp:10:6:10:24 | test_indirect_throw | test.cpp:8:17:8:34 | throw ... [ExceptionA] | test.cpp:10:6:10:24 | test_indirect_throw [ExceptionA] | Function test_indirect_throw is declared noexcept(true) but can throw exceptions of type ExceptionA. |
-| test.cpp:14:6:14:26 | test_indirect_throw_2 | test.cpp:8:17:8:34 | throw ... [ExceptionA] | test.cpp:14:6:14:26 | test_indirect_throw_2 [ExceptionA] | Function test_indirect_throw_2 is declared noexcept(true) but can throw exceptions of type ExceptionA. |
+| test.cpp:10:6:10:27 | noexceptIndirectThrowA | test.cpp:8:17:8:34 | throw ... [ExceptionA] | test.cpp:10:6:10:27 | noexceptIndirectThrowA [ExceptionA] | Function noexceptIndirectThrowA is declared noexcept(true) but can throw exceptions of type ExceptionA. |
+| test.cpp:12:6:12:24 | test_indirect_throw | test.cpp:8:17:8:34 | throw ... [ExceptionA] | test.cpp:12:6:12:24 | test_indirect_throw [ExceptionA] | Function test_indirect_throw is declared noexcept(true) but can throw exceptions of type ExceptionA. |
+| test.cpp:16:6:16:26 | test_indirect_throw_2 | test.cpp:8:17:8:34 | throw ... [ExceptionA] | test.cpp:16:6:16:26 | test_indirect_throw_2 [ExceptionA] | Function test_indirect_throw_2 is declared noexcept(true) but can throw exceptions of type ExceptionA. |
+| test.cpp:33:6:33:26 | test_indirect_throw_6 | test.cpp:8:17:8:34 | throw ... [ExceptionA] | test.cpp:33:6:33:26 | test_indirect_throw_6 [ExceptionA] | Function test_indirect_throw_6 is declared noexcept(true) but can throw exceptions of type ExceptionA. |

cpp/autosar/test/rules/A15-4-2/test.cpp

@@ -6,6 +6,8 @@ void test_throw() noexcept(true) {
 }
 
 void throwA() { throw ExceptionA(); }
+void indirectThrowA() { throwA(); }
+void noexceptIndirectThrowA() noexcept { throwA(); } // NON_COMPLIANT
 
 void test_indirect_throw() noexcept(true) {
   throwA(); // NON_COMPLIANT - function marked as noexcept(true)
@@ -21,4 +23,13 @@ void test_indirect_throw_3() noexcept(false) {
 
 void test_indirect_throw_4() {
   throwA(); // COMPLIANT - function marked as noexcept(false)
+}
+
+void test_indirect_throw_5() noexcept {
+  noexceptIndirectThrowA(); // COMPLIANT - noexceptIndirectThrowA would call
+                            // std::terminate() if ExceptionA is thrown
+}
+
+void test_indirect_throw_6() noexcept {
+  indirectThrowA(); // NON_COMPLIANT
 }

cpp/cert/test/rules/ERR55-CPP/HonorExceptionSpecifications.expected

@@ -1,8 +1,35 @@
 edges
+| test_dynamic_specification.cpp:9:6:9:22 | throw_logic_error [logic_error] | test_dynamic_specification.cpp:34:3:34:19 | call to throw_logic_error [logic_error] |
+| test_dynamic_specification.cpp:9:6:9:22 | throw_logic_error [logic_error] | test_dynamic_specification.cpp:38:3:38:19 | call to throw_logic_error [logic_error] |
+| test_dynamic_specification.cpp:9:6:9:22 | throw_logic_error [logic_error] | test_dynamic_specification.cpp:43:3:43:19 | call to throw_logic_error [logic_error] |
+| test_dynamic_specification.cpp:9:28:9:58 | throw ... [logic_error] | test_dynamic_specification.cpp:9:6:9:22 | throw_logic_error [logic_error] |
 | test_dynamic_specification.cpp:22:3:22:24 | throw ... [exception] | test_dynamic_specification.cpp:20:6:20:49 | test_simple_exception_spec_covered_inherited [exception] |
 | test_dynamic_specification.cpp:29:3:29:24 | throw ... [exception] | test_dynamic_specification.cpp:28:6:28:30 | test_no_throw_contravened [exception] |
-| test_no_except.cpp:8:3:8:14 | throw ... [char *] | test_no_except.cpp:7:6:7:23 | test_noexcept_true [char *] |
+| test_dynamic_specification.cpp:33:6:33:31 | indirect_throw_logic_error [logic_error] | test_dynamic_specification.cpp:48:3:48:28 | call to indirect_throw_logic_error [logic_error] |
+| test_dynamic_specification.cpp:34:3:34:19 | call to throw_logic_error [logic_error] | test_dynamic_specification.cpp:33:6:33:31 | indirect_throw_logic_error [logic_error] |
+| test_dynamic_specification.cpp:38:3:38:19 | call to throw_logic_error [logic_error] | test_dynamic_specification.cpp:37:6:37:46 | indirect_throw_logic_error_but_terminates [logic_error] |
+| test_dynamic_specification.cpp:43:3:43:19 | call to throw_logic_error [logic_error] | test_dynamic_specification.cpp:41:6:41:48 | indirect_throw_logic_error_but_terminates_2 [logic_error] |
+| test_dynamic_specification.cpp:48:3:48:28 | call to indirect_throw_logic_error [logic_error] | test_dynamic_specification.cpp:47:6:47:25 | test_indirect_throws [logic_error] |
+| test_no_except.cpp:4:3:4:20 | throw ... [ExceptionA] | test_no_except.cpp:3:6:3:15 | test_throw [ExceptionA] |
+| test_no_except.cpp:7:6:7:11 | throwA [ExceptionA] | test_no_except.cpp:8:25:8:30 | call to throwA [ExceptionA] |
+| test_no_except.cpp:7:6:7:11 | throwA [ExceptionA] | test_no_except.cpp:9:42:9:47 | call to throwA [ExceptionA] |
+| test_no_except.cpp:7:6:7:11 | throwA [ExceptionA] | test_no_except.cpp:12:3:12:8 | call to throwA [ExceptionA] |
+| test_no_except.cpp:7:6:7:11 | throwA [ExceptionA] | test_no_except.cpp:16:3:16:8 | call to throwA [ExceptionA] |
+| test_no_except.cpp:7:17:7:34 | throw ... [ExceptionA] | test_no_except.cpp:7:6:7:11 | throwA [ExceptionA] |
+| test_no_except.cpp:8:6:8:19 | indirectThrowA [ExceptionA] | test_no_except.cpp:33:3:33:16 | call to indirectThrowA [ExceptionA] |
+| test_no_except.cpp:8:25:8:30 | call to throwA [ExceptionA] | test_no_except.cpp:8:6:8:19 | indirectThrowA [ExceptionA] |
+| test_no_except.cpp:9:42:9:47 | call to throwA [ExceptionA] | test_no_except.cpp:9:6:9:27 | noexceptIndirectThrowA [ExceptionA] |
+| test_no_except.cpp:12:3:12:8 | call to throwA [ExceptionA] | test_no_except.cpp:11:6:11:24 | test_indirect_throw [ExceptionA] |
+| test_no_except.cpp:16:3:16:8 | call to throwA [ExceptionA] | test_no_except.cpp:15:6:15:26 | test_indirect_throw_2 [ExceptionA] |
+| test_no_except.cpp:33:3:33:16 | call to indirectThrowA [ExceptionA] | test_no_except.cpp:32:6:32:26 | test_indirect_throw_6 [ExceptionA] |
 #select
 | test_dynamic_specification.cpp:20:6:20:49 | test_simple_exception_spec_covered_inherited | test_dynamic_specification.cpp:22:3:22:24 | throw ... [exception] | test_dynamic_specification.cpp:20:6:20:49 | test_simple_exception_spec_covered_inherited [exception] | test_simple_exception_spec_covered_inherited can throw an exception of type std::exception but has a dynamic exception specification that does not specify this type. |
 | test_dynamic_specification.cpp:28:6:28:30 | test_no_throw_contravened | test_dynamic_specification.cpp:29:3:29:24 | throw ... [exception] | test_dynamic_specification.cpp:28:6:28:30 | test_no_throw_contravened [exception] | test_no_throw_contravened can throw an exception of type std::exception but has a dynamic exception specification that does not specify this type. |
-| test_no_except.cpp:7:6:7:23 | test_noexcept_true | test_no_except.cpp:8:3:8:14 | throw ... [char *] | test_no_except.cpp:7:6:7:23 | test_noexcept_true [char *] | test_noexcept_true can throw an exception of type char * but is marked noexcept(true). |
+| test_dynamic_specification.cpp:37:6:37:46 | indirect_throw_logic_error_but_terminates | test_dynamic_specification.cpp:9:28:9:58 | throw ... [logic_error] | test_dynamic_specification.cpp:37:6:37:46 | indirect_throw_logic_error_but_terminates [logic_error] | indirect_throw_logic_error_but_terminates can throw an exception of type std::logic_error but has a dynamic exception specification that does not specify this type. |
+| test_dynamic_specification.cpp:41:6:41:48 | indirect_throw_logic_error_but_terminates_2 | test_dynamic_specification.cpp:9:28:9:58 | throw ... [logic_error] | test_dynamic_specification.cpp:41:6:41:48 | indirect_throw_logic_error_but_terminates_2 [logic_error] | indirect_throw_logic_error_but_terminates_2 can throw an exception of type std::logic_error but has a dynamic exception specification that does not specify this type. |
+| test_dynamic_specification.cpp:47:6:47:25 | test_indirect_throws | test_dynamic_specification.cpp:9:28:9:58 | throw ... [logic_error] | test_dynamic_specification.cpp:47:6:47:25 | test_indirect_throws [logic_error] | test_indirect_throws can throw an exception of type std::logic_error but has a dynamic exception specification that does not specify this type. |
+| test_no_except.cpp:3:6:3:15 | test_throw | test_no_except.cpp:4:3:4:20 | throw ... [ExceptionA] | test_no_except.cpp:3:6:3:15 | test_throw [ExceptionA] | test_throw can throw an exception of type ExceptionA but is marked noexcept(true). |
+| test_no_except.cpp:9:6:9:27 | noexceptIndirectThrowA | test_no_except.cpp:7:17:7:34 | throw ... [ExceptionA] | test_no_except.cpp:9:6:9:27 | noexceptIndirectThrowA [ExceptionA] | noexceptIndirectThrowA can throw an exception of type ExceptionA but is marked noexcept(true). |
+| test_no_except.cpp:11:6:11:24 | test_indirect_throw | test_no_except.cpp:7:17:7:34 | throw ... [ExceptionA] | test_no_except.cpp:11:6:11:24 | test_indirect_throw [ExceptionA] | test_indirect_throw can throw an exception of type ExceptionA but is marked noexcept(true). |
+| test_no_except.cpp:15:6:15:26 | test_indirect_throw_2 | test_no_except.cpp:7:17:7:34 | throw ... [ExceptionA] | test_no_except.cpp:15:6:15:26 | test_indirect_throw_2 [ExceptionA] | test_indirect_throw_2 can throw an exception of type ExceptionA but is marked noexcept(true). |
+| test_no_except.cpp:32:6:32:26 | test_indirect_throw_6 | test_no_except.cpp:7:17:7:34 | throw ... [ExceptionA] | test_no_except.cpp:32:6:32:26 | test_indirect_throw_6 [ExceptionA] | test_indirect_throw_6 can throw an exception of type ExceptionA but is marked noexcept(true). |

cpp/cert/test/rules/ERR55-CPP/test_dynamic_specification.cpp

@@ -27,4 +27,28 @@ void test_no_throw() throw() { // COMPLIANT
 
 void test_no_throw_contravened() throw() { // NON_COMPLIANT
   throw std::exception();
+}
+
+class DummyException {};
+void indirect_throw_logic_error() throw(std::logic_error) {
+  throw_logic_error(); // Exception flows out of function as specification is
+                       // compatible
+}
+void indirect_throw_logic_error_but_terminates() throw() { // NON_COMPLIANT
+  throw_logic_error(); // Exception does not flow out of function due to
+                       // specification
+}
+void indirect_throw_logic_error_but_terminates_2() // NON_COMPLIANT
+    throw(DummyException) {
+  throw_logic_error(); // Exception does not flow out of function due to
+                       // specification
+}
+
+void test_indirect_throws() throw() { // NON_COMPLIANT
+  indirect_throw_logic_error();
+}
+
+void test_indirect_throws_but_terminated() throw() { // COMPLIANT
+  indirect_throw_logic_error_but_terminates();
+  indirect_throw_logic_error_but_terminates_2();
 }

cpp/cert/test/rules/ERR55-CPP/test_no_except.cpp

@@ -1,9 +1,34 @@
-#include <stdexcept>
+class ExceptionA {};
 
-void test_noexcept_false() { // COMPLIANT
-  throw "test";
+void test_throw() noexcept(true) {
+  throw ExceptionA(); // NON_COMPLIANT - function marked as noexcept(true)
 }
 
-void test_noexcept_true() noexcept(true) { // NON_COMPLIANT
-  throw "test";
+void throwA() { throw ExceptionA(); }
+void indirectThrowA() { throwA(); }
+void noexceptIndirectThrowA() noexcept { throwA(); } // NON_COMPLIANT
+
+void test_indirect_throw() noexcept(true) {
+  throwA(); // NON_COMPLIANT - function marked as noexcept(true)
+}
+
+void test_indirect_throw_2() noexcept {
+  throwA(); // NON_COMPLIANT - function marked as noexcept(true)
+}
+
+void test_indirect_throw_3() noexcept(false) {
+  throwA(); // COMPLIANT - function marked as noexcept(false)
+}
+
+void test_indirect_throw_4() {
+  throwA(); // COMPLIANT - function marked as noexcept(false)
+}
+
+void test_indirect_throw_5() noexcept {
+  noexceptIndirectThrowA(); // COMPLIANT - noexceptIndirectThrowA would call
+                            // std::terminate() if ExceptionA is thrown
+}
+
+void test_indirect_throw_6() noexcept {
+  indirectThrowA(); // NON_COMPLIANT
 }

cpp/common/src/codingstandards/cpp/exceptions/ExceptionFlow.qll

@@ -4,6 +4,7 @@
 
 import cpp
 import codingstandards.cpp.standardlibrary.Exceptions
+import codingstandards.cpp.exceptions.ExceptionSpecifications
 import ThirdPartyExceptions
 
 /*
@@ -312,7 +313,28 @@ class ReThrowExprThrowingExpr extends ReThrowExpr, ThrowingExpr {
 
 /** An expression which calls a function which may throw an exception. */
 class FunctionCallThrowingExpr extends FunctionCall, ThrowingExpr {
-  override ExceptionType getAnExceptionType() { result = getAFunctionThrownType(getTarget(), _) }
+  override ExceptionType getAnExceptionType() {
+    exists(Function target |
+      target = getTarget() and
+      result = getAFunctionThrownType(target, _) and
+      // [expect.spec] states that throwing an exception type that is prohibited
+      // by the specification will result in the program terminating, unless
+      // a custom `unexpected_handler` is registered that throws an exception type
+      // which is compatible with the dynamic exception specification, or the
+      // dynamic exception specification lists `std::bad_exception`, in which case
+      // a `std::bad_exception` is thrown.
+      // As dynamic exception specifications and the `unexpected_handler` are both
+      // deprecated in C++14 and removed in C++17, we assume a default
+      // `std::unexpected` handler that calls `std::terminate` and therefore
+      // do not propagate such exceptions to the call sites for the function.
+      not (
+        hasDynamicExceptionSpecification(target) and
+        not result = getAHandledExceptionType(target.getAThrownType())
+        or
+        isNoExceptTrue(target)
+      )
+    )
+  }
 }
 
 module ExceptionPathGraph {