Dec 28, 2024 · Dec 17, 2024 · Dec 18, 2024 · Dec 19, 2024
diff --git a/change_notes/2024-12-17-fix-fp-824-a15-4-4 b/change_notes/2024-12-17-fix-fp-824-a15-4-4
 - `A15-4-4` - `MissingNoExcept.ql`:
   - Reduce false positives by not reporting on functions that have a noexcept specification with a complex expression or call other such functions.
diff --git a/cpp/autosar/src/rules/A15-4-4/MissingNoExcept.ql b/cpp/autosar/src/rules/A15-4-4/MissingNoExcept.ql
 import codingstandards.cpp.exceptions.ExceptionSpecifications
 import codingstandards.cpp.exceptions.ExceptionFlow

 // These functions have a noexcept specification that could not be resolved
 // to noexcept(true). So either, they are noexcept(false) functions which
 // means, they can throw an exception OR they have an expression which
 // could not be resolved to "true" or "false". Even in this case, lets
 // be more conservative and assume they may thrown an exception.
 class FunctionWithUnknownNoExcept extends Function {
  FunctionWithUnknownNoExcept() {
    // Exists a noexcept specification but not noexcept(true)
    exists(this.getADeclarationEntry().getNoExceptExpr()) and
    not isNoExceptTrue(this)
  }
 }

 // This predicate checks if a function can call to other functions
 // that may have a noexcept specification which cannot be resolved to
 // noexcept(true).
 predicate mayCallThrowingFunctions(Function f) {
  // Exists a call in this function
  exists(Call fc |
    fc.getEnclosingFunction() = f and
    (
      // Either this call is to a function with an unknown noexcept OR
      fc.getTarget() instanceof FunctionWithUnknownNoExcept
      or
      // That function can further have calls to unknown noexcept functions.
      mayCallThrowingFunctions(fc.getTarget())
    )
  )
 }

 from Function f
 where
  not isExcluded(f, Exceptions1Package::missingNoExceptQuery()) and
  not isNoExceptTrue(f) and
  // Not explicitly marked noexcept(false)
  not isNoExceptExplicitlyFalse(f) and
  // Not having a noexcept specification that
  // could not be computed as true or false above.
  not exists(f.getADeclarationEntry().getNoExceptExpr()) and
  // Not calling function(s) which have a noexcept specification that
  // could not be computed as true.
  not mayCallThrowingFunctions(f) and
  // Not compiler generated
  not f.isCompilerGenerated() and
  // The function is defined in this database
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		- `A15-4-4` - `MissingNoExcept.ql`:
		- Reduce false positives by not reporting on functions that have a noexcept specification with a complex expression or call other such functions.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -19,6 +19,36 @@ import codingstandards.cpp.autosar
		import codingstandards.cpp.exceptions.ExceptionSpecifications
		import codingstandards.cpp.exceptions.ExceptionFlow

		// These functions have a noexcept specification that could not be resolved
		// to noexcept(true). So either, they are noexcept(false) functions which
		// means, they can throw an exception OR they have an expression which
		// could not be resolved to "true" or "false". Even in this case, lets
		// be more conservative and assume they may thrown an exception.
		class FunctionWithUnknownNoExcept extends Function {
		FunctionWithUnknownNoExcept() {
		// Exists a noexcept specification but not noexcept(true)
		exists(this.getADeclarationEntry().getNoExceptExpr()) and
		not isNoExceptTrue(this)
		}
		}

		// This predicate checks if a function can call to other functions
		// that may have a noexcept specification which cannot be resolved to
		// noexcept(true).
		predicate mayCallThrowingFunctions(Function f) {
		// Exists a call in this function
		exists(Call fc \|
		fc.getEnclosingFunction() = f and
		(
		// Either this call is to a function with an unknown noexcept OR
		fc.getTarget() instanceof FunctionWithUnknownNoExcept
		or
		// That function can further have calls to unknown noexcept functions.
		mayCallThrowingFunctions(fc.getTarget())
		)
		)
		}

		from Function f
		where
		not isExcluded(f, Exceptions1Package::missingNoExceptQuery()) and
Expand All		@@ -28,6 +58,12 @@ where
		not isNoExceptTrue(f) and
		// Not explicitly marked noexcept(false)
		not isNoExceptExplicitlyFalse(f) and
		// Not having a noexcept specification that
		// could not be computed as true or false above.
		not exists(f.getADeclarationEntry().getNoExceptExpr()) and
		// Not calling function(s) which have a noexcept specification that
		// could not be computed as true.
		not mayCallThrowingFunctions(f) and
		// Not compiler generated
		not f.isCompilerGenerated() and
		// The function is defined in this database
Expand Down