WXTRN instruction

The WXTRN statement identifies "weak external" symbols referred to in a source module but defined in another source module. The WXTRN instruction differs from the EXTRN instruction (see EXTRN instruction) as follows:

Read syntax diagramSkip visual syntax diagram>>-+-----------------+--WXTRN----------------------------------->
   '-sequence_symbol-'         
 
   .-,-------------------------------.  
   V                                 |  
>----+-external_symbol-------------+-+-------------------------><
     |       .-,---------------.   |    
     |       V                 |   |    
     '-PART(---external_symbol-+-)-'    
 
sequence_symbol
is a sequence symbol.
external_symbol
is a relocatable symbol that is not:
PART(external_symbol)
external_symbol is a relocatable symbol as described above, that also:

The external symbols identified by a WXTRN instruction have the same properties as the external symbols identified by the EXTRN instruction. However, the type code assigned to these external symbols differs.

V-Type Address Constant: If a symbol, specified in a V-type address constant, is also identified by a WXTRN instruction, it is assigned the same ESD type code as the symbol in the WXTRN instruction, and is treated by the linkage editor as a weak external symbol.

If an external symbol is identified by both an EXTRN and WXTRN instruction in the same source module, the first declaration takes precedence, and subsequent declarations are flagged with diagnostic messages.


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