Linker Can Indiscriminately Bind Different Types

The information in this article applies to:

• Microsoft LINK for MS-DOS, versions 1.x, 2.x, 3.x, 4.x, 5.01, 5.02, 5.03, 5.05, 5.1, 5.11, 5.13, 5.15, 5.3, 5.31.009, 5.5, and 5.6

The object module format used by the Microsoft languages contains a record type that is used to bind symbol definitions to symbol references in other modules. This record is known as a "fixup." As defined by Intel, the fixup record type contains no information as to the type of data that is to be fixed up. Under certain circumstances, this can cause unexpected and undesired binding at link time. The code below demonstrates such an instance:

    /*----- FILE1.C -----*/

    void bar( void );

    void main( void )
    {
        bar();
    }


    /*----- FILE2.C -----*/

    int bar;

The linker has no way of determining the types of the reference to, and definition of, bar. This is a limitation of the object file format. If an include file was used to prototype bar and was then included in both files, the compiler could have detected the redefinition of bar.

This information applies to all versions of LINK.