Rebuild when an #included header changes #31
2026-07-31
test: header-change incrementality across every compile path
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One header per pass, asserting both directions — the objects that include it recompile, the ones that don't are untouched — then running the binary, since "was recompiled" only matters if the program agrees with itself. Covers the module interface (a macro in its global module fragment decides an exported class's layout), the implementation unit, a C source, an idle rebuild that must recompile nothing, and an object whose depfile is gone. The implementation unit's header has a space in its name so the depfile spells it escaped.
fix(incremental): relink when a C or CUDA object is rebuilt
The C compile loop sets no repack flag, and the "is any object newer than the archive" sweep only walked interfaces and implementations. So editing a .c recompiled its object and then linked nothing: the archive and the executable kept the previous one. Surfaced by the header-change test, where a rebuilt counter.c produced a binary still printing the old value.
feat(incremental): rebuild when an #included header changes
The staleness check compared an artifact against its own source and its module imports. Headers were in neither set: the scanner reads `import` lines, and a .cppm or .cpp keeps its mtime when a header it includes is edited — so the build reported nothing to do and left objects compiled against the previous contents. Same silent mixed-layout binary as issue 27, reached through #include instead of import. Ask the compiler what it actually opened. Every C++ and C compile now passes -MD -MF <artifact>.d, and Check reads that depfile back through NewestPrerequisite, comparing every prerequisite's mtime against the artifact. A missing depfile (an object from a crafter-build that wrote none) or a prerequisite that no longer exists reads as "rebuild": neither is evidence of freshness. The parser unescapes make syntax rather than splitting on whitespace, since clang wraps depfiles onto continuation lines and escapes spaces in filenames.