Bootstrap warning "Use `--keep-stage-std` ..." persists even when the option is used

cushionbadak · January 4, 2024, 9:19am

A pull request Add `--keep-stage-std` to `x.py` for keeping only standard library artifacts by ecstatic-morse · Pull Request #77120 · rust-lang/rust · GitHub introduces an option --keep-stage-std for bootstrapping (./x), but it does not provide any meaningful action, but it is just another syntactic bloat of --keep-stage option.

As you can see in the pull request, it pipes the option --keep-stage-std value to config.keep_stage_std and flags.keep_stage_std, but I cannot find any unique functionality of config.keep_stage_std value compared to config.keep_stage.

~~I think keeping this option is unnecessary. Am I missing something?~~

~~Reference: Following is the only part~~ I found where config.keep_stage_std value used:

github.com

rust-lang/rust/blob/139fb2214675fed8143a12f6287a3a1e6e2e866d/src/bootstrap/src/core/build_steps/compile.rs#L141-L151


      
          if builder.config.keep_stage.contains(&compiler.stage)
              || builder.config.keep_stage_std.contains(&compiler.stage)
          {
              builder.info("WARNING: Using a potentially old libstd. This may not behave well.");
          
              copy_third_party_objects(builder, &compiler, target);
              copy_self_contained_objects(builder, &compiler, target);
          
              builder.ensure(StdLink::from_std(self, compiler));
              return;
          }

EDIT: I discovered another logic that distinguishes keep_stage and keep_stage_std:

github.com

rust-lang/rust/blob/090d5eac722000906cc00d991f2bf052b0e388c3/src/bootstrap/src/core/build_steps/compile.rs#L1255-L1270


      
          fn run(self, builder: &Builder<'_>) {
              let compiler = self.compiler;
              let target = self.target;
              let backend = self.backend;
          
              builder.ensure(Rustc::new(compiler, target));
          
              if builder.config.keep_stage.contains(&compiler.stage) {
                  builder.info(
                      "WARNING: Using a potentially old codegen backend. \
                      This may not behave well.",
                  );
                  // Codegen backends are linked separately from this step today, so we don't do
                  // anything here.
                  return;
              }

EDIT: changed the title from "Bootstrap option --keep-stage-std is meaningless" to "Bootstrap warning "Use --keep-stage-std ..." persists even when the option is used". I'm rethinking whether the option is actually meaningless. Sorry for the confusion.

From my understanding:

keep_stage copies third party objects and copy_self_contained_objects, skipping the compiler build
keep_stage_std also copies these objects but doesn't skip the compiler build.

I apologize for my earlier mistake. Let's discuss this option further. My initial misunderstanding and post on this forum were prompted by a persistent warning message from the bootstrapping script ./x. It shows "WARNING: Use --keep-stage-std if you want to rebuild the compiler when it changes", even if I use multiple --keep-stage-std options like ./x build compiler --keep-stage 0 --keep-stage 1 --keep-stage-std 0 --keep-stage-std 1. After researching on GitHub, I realized that this warning only depends on the keep_stage configuration, not the presense of keep_stage_std.

github.com

rust-lang/rust/blob/090d5eac722000906cc00d991f2bf052b0e388c3/src/bootstrap/src/core/build_steps/compile.rs#L821-L826


      
          if builder.config.keep_stage.contains(&compiler.stage) {
              builder.info("WARNING: Using a potentially old librustc. This may not behave well.");
              builder.info("WARNING: Use `--keep-stage-std` if you want to rebuild the compiler when it changes");
              builder.ensure(RustcLink::from_rustc(self, compiler));
              return;
          }

I find this rigid method of showing warning messages to be confusing and not straightforward.

system · April 3, 2024, 9:19am

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Bootstrap warning "Use `--keep-stage-std` ..." persists even when the option is used

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