dexonsmith added a comment. > This patch fixes dependency scanning of a TU with prebuilt modular/PCH > dependencies. > > Such modules/PCH might have been built using non-minimized files, while > dependency scanner does use the minimized versions of source files. Implicit > build doesn't like the discrepancy in file sizes and errors out. > > The issues is worked around by padding the minimized files with whitespace in > such scenarios. This approach throws away one advantage of source > minimization (the memory savings), but still keeps the benefits of faster > preprocessing/lexing.
I'm not sure this is the right approach. - Don't PCHs sometimes validate based on hashes of inputs instead of size? At least, that has been discussed, and this patch would block making the change. - Can PCHs embed inputs, like modules can? How would that work (or not) minimized sources generally? - What happens if the PCH has a delayed diagnostic, triggered when parsing the next thing? Will the fix-it point in the wrong place? (Are there other things that depend on reading the original sources when reading a PCH?) A few other ideas: 1. Disable PCH validation when minimizing. (Is that less robust than your current workaround? If so, can you explain why?) 2. Use the original PCH header in the scanning `-cc1`s (translate `-include-pch` to `-include`) and switch back in the generated `-cc1`s (back to `-include-pch`). 3. Embed instructions in the PCH for how to build it, and make a "minimized" version of the PCH. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D104465/new/ https://reviews.llvm.org/D104465 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
