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Add info message for -Wall command #48765

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merged 3 commits into from
Mar 14, 2018
Merged

Add info message for -Wall command #48765

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c97c7bf
Add info message for -Wall command
Phlosioneer Mar 6, 2018
1246eef
Fix trailing whitespace
Phlosioneer Mar 6, 2018
c1337cd
Update -Wall message based on feedback
Phlosioneer Mar 13, 2018
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17 changes: 17 additions & 0 deletions src/librustc_driver/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1136,6 +1136,16 @@ fn usage(verbose: bool, include_unstable_options: bool) {
verbose_help);
}

fn print_wall_help() {
println!("
The flag -Wall does not exist in rustc. Most useful lints are enabled by default.
Use `rustc -W help` to see all available lints. The most used lints that are not
enabled by default covered by -Wunused; however, the best practice is to put
warning settings in the crate root using `#![warn(unused)]` instead of using
the command line flag directly.
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I'm fine with the feature. I would like to have a native speaker take a look over this. cc @rust-lang/docs

Maybe something closer to:

The flag `-Wall` does not exist in `rustc`. Most useful lints are enabled by default.
Use `rustc -W help` to see all available lints. The most used lints that are not
enabled by default are covered by `-Wunused`; however, the best practice is to
put warning settings in the crate root using `#![warn(LINT_NAME)]` instead of using
the command line flag directly.

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The most used lints that are not enabled by default are covered by -Wunused

Is there any particular reason why -Wunused is being called out here? Why unused vs. other lint checks?

the best practice is to put warning settings...

I might say "it's more common to put warning settings...", but I don't feel strongly

Other than that, seems good to me 👍

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unused turns on half of the allowed-by-default lints that I've ever seen used:

  • unused-qualifications
  • unused-results
  • unused-import-braces
  • unused-extern-crates

The others that I've personally seen used are:

  • missing-docs
  • trivial-casts
  • trivial-numeric-casts
  • unreachable-pub

And given that a LOT of crates in the ecosystem have #![warn(unused)], I thought it was the most relevant one to mention.

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Actually, looking at the -W help output, -Wunused only turns on unused-extern-crates... I thought it did all the unused-* lints?
I might have to go step-up my #![warn(unused-*)] lines in my projects.

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Actually, looking at the -W help output, -Wunused only turns on unused-extern-crates

taken from rustc -W help

Lint groups provided by rustc:

                   name  sub-lints
                   ----  ---------
               warnings  all lints that are set to issue warnings
              bad-style  non-camel-case-types, non-snake-case, non-upper-case-globals
    future-incompatible  private-in-public, pub-use-of-private-extern-crate, patterns-in-fns-without-body, safe-extern-statics, invalid-type-param-default, legacy-directory-ownership, legacy-imports, legacy-constructor-visibility, resolve-trait-on-defaulted-unit, missing-fragment-specifier, illegal-floating-point-literal-pattern, anonymous-parameters, parenthesized-params-in-types-and-modules, late-bound-lifetime-arguments, safe-packed-borrows, incoherent-fundamental-impls, coerce-never, tyvar-behind-raw-pointer
                 unused  unused-imports, unused-variables, unused-assignments, dead-code, unused-mut, unreachable-code, unreachable-patterns, unused-must-use, unused-unsafe, path-statements, unused-attributes, unused-macros, unused-allocation, unused-doc-comment, unused-extern-crates, unused-features, unused-parens


Compiler plugins can provide additional lints and lint groups. To see a listing of these, re-run `rustc -W help` with a crate filename.

");
}

fn describe_lints(sess: &Session, lint_store: &lint::LintStore, loaded_plugins: bool) {
println!("
Available lint options:
Expand Down Expand Up @@ -1380,6 +1390,13 @@ pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
return None;
}

// Handle the special case of -Wall.
let wall = matches.opt_strs("W");
if wall.iter().any(|x| *x == "all") {
print_wall_help();
return None;
}

// Don't handle -W help here, because we might first load plugins.
let r = matches.opt_strs("Z");
if r.iter().any(|x| *x == "help") {
Expand Down