Preprocessor support

The generator understands a limited subset of C preprocessor directives embedded in Fortran sources.

Supported range

• Object-like #define macros.
• Simple function-like macros without token pasting or variadic arguments.
• Conditionals using #if defined(NAME), #if !defined(NAME), #ifdef, #ifndef, #else, and #endif.
• Macros declared inside modules are tracked so later references expand within the module.

Unsupported features

• #include directives.
• #elif branches and general #if expressions beyond defined(...).
• Macros that use token pasting (##), stringification (#), variadic arguments, or line continuation characters (\).
• Complex expression evaluation inside #if directives or macro bodies.

Known limitations

• Expansion is purely textual and does not perform full C preprocessing.
• Only macros defined in the current file are considered; macros from included files or build system definitions are ignored.
• Directives that cannot be interpreted are preserved verbatim in the generated output.