[PATCH] D139168: [C++20] [Modules] [ClangScanDeps] Enable to print make-style dependency file within P1689 format (4/4)

Sun Jan 8 18:42:13 PST 2023

ben.boeckel added a comment.

In D139168#4034885 <https://reviews.llvm.org/D139168#4034885>, @ChuanqiXu wrote:

> @Arthapz Great to hear that! It is pretty important for us to know there are more build systems which are using these functionality. BTW, for header units, it is still under discussion that how should build system and compiler interact about header units. It is still unclear whether or not the header units should be transparent to build systems (and other tools).

Header units have even more need to be involved in the build graph than named units. ODR violations and cache invalidation problems await anyone just winging it on header units (at least that's the understanding I've gotten from SG15 meetings).

> I mean, it is possible to get the make-style format information by `clang-scan-deps -format=make --compilation-database=db.json`. (Although it sounds not smart indeed)

I don't see the benefit of having to run two commands to get this information.

> Then how do you feel about the current strategy? `clang-scan-deps --format=p1689 --compilation-database=db.json`. Then if every commands in db.json has the same `-MF` value, it should be able to satisfy your requirement.

This seems…reasonable. No worse than the other lies we have to tell in a databse. FWIW, the same with should happen with `-MT`.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D139168/new/

https://reviews.llvm.org/D139168