Search-path helpers live inside the C preprocessor

Found 2026-08-19 while measuring [[feature-a-build-a-reduced-compiler-by-selecting-frontends-and-targets]] by omission.

Omitting the C frontend (clexer.inc, cparser.inc, cpreproc.inc) gives 11 errors. Six are AddPasUnitDir and one is AddPasIncDir — called from compiler.pas's ordinary command-line handling for -Fu and -I, which have nothing to do with C:

compiler.pas(723,7)  AddPasUnitDir      compiler.pas(729,7)  AddPasIncDir
compiler.pas(736,7)  AddCIncludeDir     compiler.pas(737,7)  AddPasUnitDir
compiler.pas(906,7)  AddPasUnitDir      compiler.pas(913,7)  AddPasUnitDir
compiler.pas(915,5)  AddPasUnitDir

The name says it: AddPas... in cpreproc.inc. It is a misplacement, not coupling — nothing about a Pascal unit search path belongs to the C preprocessor, and the only reason it sits there is that the C include-path code needed a list first.

Fix

Move the three Add*Dir helpers (and whatever state they own) to a shared file — defs.inc or a small search-path section in parser.inc. No behaviour change; omit-c drops from 11 sites to about 4, and the remaining four are the real ones (CLexAppend, CLexAll, ParseCProgram, and one in parser.inc).

Worth doing independently of the reduction feature: today a reader looking for how -Fu is handled has no reason to open the C preprocessor.

Gate

Track A's: make compiler/pascal26 (byte-identical fixedpoint) + tools/gate.sh quick.