MISRA C++:2008 Rule 15-3-7

Where multiple handlers are provided in a single try-catch statement or function-try-block, any ellipsis (catch-all) handler shall occur last

Description

Rule Definition

Where multiple handlers are provided in a single try-catch statement or function-try-block, any ellipsis (catch-all) handler shall occur last.

Rationale

In a try-catch statement or function-try block, the compiler matches the raised exception with a catch() handler. The catch(…) handler matches any exception. Handlers after the catch-all handler within the same try-catch statement or function try-block are ignored by the compiler during the exception handling process and are unreachable code.

Having a handler after the catch-all handler might result in developer confusion as to why certain intended handlers are not being executed. Likewise, the catch-all handler might not handle the exception in the way the developer intends, resulting in confusion.

Polyspace Implementation

Polyspace^® raises this defect whenever a handler appears after the catch-all handler within the try-catch statement or function try-block.

Troubleshooting

If you expect a rule violation but Polyspace does not report it, see Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

Handlers After the Catch-All Handler Are Noncompliant

#include <iostream>
#include <exception>

using namespace std;

int main()
{

	try
	{
		//some code
	} catch(exception& e1) {     //Compliant
	
		//...
	
	} catch(...) {               //Compliant
		
		//...
	
	} catch(exception& e2) {     //Noncompliant
	
		//...
	
	}
	}
	
	return 0;
}

Because the catch (exception& e2) handler comes after the catch(…) handler, Polyspace flags the handler before the catch-all handler as noncompliant. This issue might result in a compilation error.

Check Information

Group: Exception Handling

Category: Required

Version History

Introduced in R2013b