Detecting errors before a program is run is a key objective of IBM VisualAge C++. Runtime errors are hard to find, and many are caused by mismatching subroutine interfaces or conflicting data definitions.
VisualAge C++ uses a scheme for early detection that encodes information about all external symbols (data and programs). If the -qextchk option has been specified, this information about external symbols is checked at bind or load time for consistency.
The Assembler Language Reference for the AIX RISC System/6000 book describes the following details of the Subroutine Linkage Convention:
Interlanguage Calling Conventions
Corresponding Data Types
Use the Subroutine Linkage Conventions in Interlanguage Calls
Sample Program: C Calling Fortran