18.3 Source Files Containing Type Information

Whenever you add GTY markers to a source file that previously had none, or create a new source file containing GTY markers, there are three things you need to do:

1. You need to add the file to the list of source files the type machinery scans. There are four cases:
   1. For a back-end file, this is usually done automatically; if not, you should add it to target_gtfiles in the appropriate port's entries in config.gcc.
   2. For files shared by all front ends, add the filename to the GTFILES variable in Makefile.in.
   3. For files that are part of one front end, add the filename to the gtfiles variable defined in the appropriate config-lang.in. For C, the file is c-config-lang.in.
   4. For files that are part of some but not all front ends, add the filename to the gtfiles variable of all the front ends that use it.
2. If the file was a header file, you'll need to check that it's included in the right place to be visible to the generated files. For a back-end header file, this should be done automatically. For a front-end header file, it needs to be included by the same file that includes gtype-lang.h. For other header files, it needs to be included in gtype-desc.c, which is a generated file, so add it to ifiles in open_base_file in gengtype.c.

   For source files that aren't header files, the machinery will generate a header file that should be included in the source file you just changed. The file will be called gt-path.h where path is the pathname relative to the gcc directory with slashes replaced by -, so for example the header file to be included in cp/parser.c is called gt-cp-parser.c. The generated header file should be included after everything else in the source file. Don't forget to mention this file as a dependency in the Makefile!

3. If a new gt-path.h file is needed, you need to arrange to add a Makefile rule that will ensure this file can be built. This is done by making it a dependency of s-gtype, like this:

        
        gt-path.h : s-gtype ; @true
   

For language frontends, there is another file that needs to be included somewhere. It will be called gtype-lang.h, where lang is the name of the subdirectory the language is contained in. It will need Makefile rules just like the other generated files.