Auto merge of rust-lang#67885 - tobithiel:fix_group_lint_allow_overri…

…de, r=Mark-Simulacrum

rustc_session: allow overriding lint level of individual lints from a group

Fixes rust-lang#58211 and fixes rust-lang/rust-clippy#4778 and fixes rust-lang/rust-clippy#4091

Instead of hard-coding the lint level preferences (from lowest to highest precedence: `lint::Allow -> lint::Warn -> lint::Deny -> lint::Forbid`), the position of the argument in the command line gets taken into account.

Examples:
1. Passing `-D unused -A unused-variables` denies everything in the lint group `unused` **except** `unused-variables` which is explicitly allowed.
1. Passing `-A unused-variables -D unused` denies everything in the lint group `unused` **including** `unused-variables` since the allow is specified before the deny (and therefore overridden by the deny).

This matches the behavior that is already being used when specifying `allow`/`deny` in the source code.

src/doc/rustc/src/command-line-arguments.md

@@ -215,21 +215,29 @@ This controls which [target](targets/index.md) to produce.
 
 This flag will set which lints should be set to the [warn level](lints/levels.md#warn).
 
+_Note:_ The order of these lint level arguments is taken into account, see [lint level via compiler flag](lints/levels.md#via-compiler-flag) for more information.
+
 <a id="option-a-allow"></a>
 ## `-A`: set lint allowed
 
 This flag will set which lints should be set to the [allow level](lints/levels.md#allow).
 
+_Note:_ The order of these lint level arguments is taken into account, see [lint level via compiler flag](lints/levels.md#via-compiler-flag) for more information.
+
 <a id="option-d-deny"></a>
 ## `-D`: set lint denied
 
 This flag will set which lints should be set to the [deny level](lints/levels.md#deny).
 
+_Note:_ The order of these lint level arguments is taken into account, see [lint level via compiler flag](lints/levels.md#via-compiler-flag) for more information.
+
 <a id="option-f-forbid"></a>
 ## `-F`: set lint forbidden
 
 This flag will set which lints should be set to the [forbid level](lints/levels.md#forbid).
 
+_Note:_ The order of these lint level arguments is taken into account, see [lint level via compiler flag](lints/levels.md#via-compiler-flag) for more information.
+
 <a id="option-z-unstable"></a>
 ## `-Z`: set unstable options
 

src/doc/rustc/src/lints/levels.md

@@ -164,6 +164,18 @@ And of course, you can mix these four flags together:
 $ rustc lib.rs --crate-type=lib -D missing-docs -A unused-variables
 ```
 
+The order of these command line arguments is taken into account. The following allows the `unused-variables` lint, because it is the last argument for that lint:
+
+```bash
+$ rustc lib.rs --crate-type=lib -D unused-variables -A unused-variables
+```
+
+You can make use of this behavior by overriding the level of one specific lint out of a group of lints. The following example denies all the lints in the `unused` group, but explicitly allows the `unused-variables` lint in that group:
+
+```bash
+$ rustc lib.rs --crate-type=lib -D unused -A unused-variables
+```
+
 ### Via an attribute
 
 You can also modify the lint level with a crate-wide attribute:

src/librustc_session/config.rs

@@ -1006,19 +1006,26 @@ pub fn get_cmd_lint_options(
  matches: &getopts::Matches,
  error_format: ErrorOutputType,
 ) -> (Vec<(String, lint::Level)>, bool, Option<lint::Level>) {
- let mut lint_opts = vec![];
+ let mut lint_opts_with_position = vec![];
  let mut describe_lints = false;
 
  for &level in &[lint::Allow, lint::Warn, lint::Deny, lint::Forbid] {
- for lint_name in matches.opt_strs(level.as_str()) {
+ for (arg_pos, lint_name) in matches.opt_strs_pos(level.as_str()) {
  if lint_name == "help" {
  describe_lints = true;
  } else {
- lint_opts.push((lint_name.replace("-", "_"), level));
+ lint_opts_with_position.push((arg_pos, lint_name.replace("-", "_"), level));
  }
  }
  }
 
+ lint_opts_with_position.sort_by_key(|x| x.0);
+ let lint_opts = lint_opts_with_position
+ .iter()
+ .cloned()
+ .map(|(_, lint_name, level)| (lint_name, level))
+ .collect();
+
  let lint_cap = matches.opt_str("cap-lints").map(|cap| {
  lint::Level::from_str(&cap)
  .unwrap_or_else(|| early_error(error_format, &format!("unknown lint level: `{}`", cap)))

src/test/ui-fulldeps/lint-group-denied-lint-allowed.rs

@@ -0,0 +1,7 @@
+// aux-build:lint-group-plugin-test.rs
+// check-pass
+// compile-flags: -D unused -A unused-variables
+
+fn main() {
+ let x = 1;
+}

src/tools/compiletest/src/runtest.rs

@@ -1478,11 +1478,7 @@ impl<'test> TestCx<'test> {
  WillExecute::No => TargetLocation::ThisDirectory(self.output_base_dir()),
  };
 
- let mut rustc = self.make_compile_args(&self.testpaths.file, output_file, emit_metadata);
-
- rustc.arg("-L").arg(&self.aux_output_dir_name());
-
- match self.config.mode {
+ let allow_unused = match self.config.mode {
  CompileFail | Ui => {
  // compile-fail and ui tests tend to have tons of unused code as
  // it's just testing various pieces of the compile, but we don't
@@ -1495,11 +1491,18 @@ impl<'test> TestCx<'test> {
  // via command line flags.
  && local_pm != Some(PassMode::Run)
  {
- rustc.args(&["-A", "unused"]);
+ AllowUnused::Yes
+ } else {
+ AllowUnused::No
  }
  }
- _ => {}
- }
+ _ => AllowUnused::No,
+ };
+
+ let mut rustc =
+ self.make_compile_args(&self.testpaths.file, output_file, emit_metadata, allow_unused);
+
+ rustc.arg("-L").arg(&self.aux_output_dir_name());
 
  self.compose_and_run_compiler(rustc, None)
  }
@@ -1710,7 +1713,8 @@ impl<'test> TestCx<'test> {
  // Create the directory for the stdout/stderr files.
  create_dir_all(aux_cx.output_base_dir()).unwrap();
  let input_file = &aux_testpaths.file;
- let mut aux_rustc = aux_cx.make_compile_args(input_file, aux_output, EmitMetadata::No);
+ let mut aux_rustc =
+ aux_cx.make_compile_args(input_file, aux_output, EmitMetadata::No, AllowUnused::No);
 
  let (dylib, crate_type) = if aux_props.no_prefer_dynamic {
  (true, None)
@@ -1819,6 +1823,7 @@ impl<'test> TestCx<'test> {
  input_file: &Path,
  output_file: TargetLocation,
  emit_metadata: EmitMetadata,
+ allow_unused: AllowUnused,
  ) -> Command {
  let is_rustdoc = self.is_rustdoc();
  let mut rustc = if !is_rustdoc {
@@ -1953,6 +1958,10 @@ impl<'test> TestCx<'test> {
  rustc.arg("-Ctarget-feature=-crt-static");
  }
 
+ if let AllowUnused::Yes = allow_unused {
+ rustc.args(&["-A", "unused"]);
+ }
+
  rustc.args(&self.props.compile_flags);
 
  rustc
@@ -2136,7 +2145,8 @@ impl<'test> TestCx<'test> {
 
  let output_file = TargetLocation::ThisDirectory(self.output_base_dir());
  let input_file = &self.testpaths.file;
- let mut rustc = self.make_compile_args(input_file, output_file, EmitMetadata::No);
+ let mut rustc =
+ self.make_compile_args(input_file, output_file, EmitMetadata::No, AllowUnused::No);
  rustc.arg("-L").arg(aux_dir).arg("--emit=llvm-ir");
 
  self.compose_and_run_compiler(rustc, None)
@@ -2149,7 +2159,8 @@ impl<'test> TestCx<'test> {
 
  let output_file = TargetLocation::ThisFile(output_path.clone());
  let input_file = &self.testpaths.file;
- let mut rustc = self.make_compile_args(input_file, output_file, EmitMetadata::No);
+ let mut rustc =
+ self.make_compile_args(input_file, output_file, EmitMetadata::No, AllowUnused::No);
 
  rustc.arg("-L").arg(self.aux_output_dir_name());
 
@@ -3000,6 +3011,7 @@ impl<'test> TestCx<'test> {
  &self.testpaths.file.with_extension(UI_FIXED),
  TargetLocation::ThisFile(self.make_exe_name()),
  emit_metadata,
+ AllowUnused::No,
  );
  rustc.arg("-L").arg(&self.aux_output_dir_name());
  let res = self.compose_and_run_compiler(rustc, None);
@@ -3487,6 +3499,11 @@ enum ExpectedLine<T: AsRef<str>> {
  Text(T),
 }
 
+enum AllowUnused {
+ Yes,
+ No,
+}
+
 impl<T> fmt::Debug for ExpectedLine<T>
 where
  T: AsRef<str> + fmt::Debug,