Add an option to emit compiler warnings when using 'rustc --parse-only'

[strangeglyph]

Right now, when using rustc to only parse an input file, only errors are displayed. There should be an option to also display warnings (and notes) without having to fully compile the program.

Trying again with a recent build of rustc, it appears that not even errors are displayed with rustc 0.5

[brson]

--parse-only results in no analysis being performed, so only syntax errors can be emitted. When I run rustc --parse-only over a file with invalid syntax I see the error. The parser doesn't appear to contain any warnings and only one 'note' (for duplicate drop blocks in structs), but I do see that emitted.

[catamorphism]

Closing because this isn't really feasible (linting comes after many other passes that get skipped with --parse-only.)

[Ghoughpteighbteau]

can we get a recommendation from one of the devs as to what arguments we should use if we are checking the syntax of a file for correctness? For error and warning highlighting.

[pnkfelix]

@Ghoughpteighbteau I'm guessing that since the lints use much info from the analysis passes, you still need those, so --no-analysis is not good enough.

Thus I suspect --no-trans is the best you can do.

[Hi-Angel]

Neither option works for me.

$ rustc main.rs --no-trans
error: Unrecognized option: 'no-trans'

$ rustc main.rs --parse-only
error: Unrecognized option: 'parse-only'

[jonas-schievink]

@Hi-Angel you probably want to use cargo check, which uses rustc --emit=metadata internally. This thread is extremely old, things have changed a lot since then.