QA·C Help - 1513

	1513	Identifier 'name' with external linkage has separate non-defining declarations in more than one location.

CMA maintenance checks

In a linkable program, only one definition of a function or object is allowed. Where several declarations (defining and non-defining) for the same name have external linkage, all declarations must be compatible.

Maintenance of a project may require changes to the types of functions or objects. When such maintenance takes place, it is important that all declarations are updated correctly. Accordingly, the more declarations for a single name, the more chance that one will be missed during maintenance.

Example:


// TU1.cpp
int foo(int);

// TU2.cpp
int foo(int);

void bar()
{
  int i = foo(10);
}

// TU3.cpp
int foo(int)
{
  return 0;
}

Maintenance requires that the function returns void, so a change is made. Linkers in general only consider names, they will not warn that the return type of the function is different in a different translation unit, and so this may be the cause of hard to find errors in a program.

Example;


// TU1.cpp
void foo(int);

// TU2.cpp
int foo(int);          // ERROR: Declaration for 'foo' was not updated.

void bar ()
{
  int i = foo(10);     // ERROR: foo no longer returns a value
}

// TU3.cpp
void foo(int)
{
  return;
}

See also:

1509 'name' has external linkage and has multiple definitions.
1510 'name' has external linkage and has incompatible declarations.
1512 Identifier 'name' with external linkage has separate declarations in multiple translation units.

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