Auto merge of #86970 - inquisitivecrystal:force-warn, r=davidtwco

Make `--force-warns` a normal lint level option

Now that `ForceWarn` is a lint level, there's no reason `--force-warns` should be treated differently from other options that set lint levels. This merges the `ForceWarn` handling in with the other lint level command line options. It also unifies all of the relevant selection logic in `compiler/rustc_lint/src/levels.rs`, rather than having some of it weirdly elsewhere.

Fixes #86958, which arose from the special-cased handling of `ForceWarn` having had an error in it.

compiler/rustc_lint/src/levels.rs

@@ -26,8 +26,6 @@ use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{source_map::MultiSpan, Span, DUMMY_SP};
 use tracing::debug;
 
-use std::cmp;
-
 fn lint_levels(tcx: TyCtxt<'_>, (): ()) -> LintLevelMap {
     let store = unerased_lint_store(tcx);
     let crate_attrs = tcx.hir().attrs(CRATE_HIR_ID);
@@ -91,12 +89,6 @@ impl<'s> LintLevelsBuilder<'s> {
         for &(ref lint_name, level) in &sess.opts.lint_opts {
             store.check_lint_name_cmdline(sess, &lint_name, level, self.crate_attrs);
             let orig_level = level;
-
-            // If the cap is less than this specified level, e.g., if we've got
-            // `--cap-lints allow` but we've also got `-D foo` then we ignore
-            // this specification as the lint cap will set it to allow anyway.
-            let level = cmp::min(level, self.sets.lint_cap);
-
             let lint_flag_val = Symbol::intern(lint_name);
 
             let ids = match store.find_lints(&lint_name) {
@@ -104,23 +96,17 @@ impl<'s> LintLevelsBuilder<'s> {
                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
             };
             for id in ids {
+                // ForceWarn and Forbid cannot be overriden
+                if let Some((Level::ForceWarn | Level::Forbid, _)) = specs.get(&id) {
+                    continue;
+                }
+
                 self.check_gated_lint(id, DUMMY_SP);
                 let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
                 specs.insert(id, (level, src));
             }
         }
 
-        for lint_name in &sess.opts.force_warns {
-            store.check_lint_name_cmdline(sess, lint_name, Level::ForceWarn, self.crate_attrs);
-            let lints = store
-                .find_lints(lint_name)
-                .unwrap_or_else(|_| bug!("A valid lint failed to produce a lint ids"));
-            for id in lints {
-                let src = LintLevelSource::CommandLine(Symbol::intern(lint_name), Level::ForceWarn);
-                specs.insert(id, (Level::ForceWarn, src));
-            }
-        }
-
         self.cur = self.sets.list.push(LintSet { specs, parent: COMMAND_LINE });
     }
 

compiler/rustc_session/src/config.rs

@@ -677,7 +677,6 @@ impl Default for Options {
             optimize: OptLevel::No,
             debuginfo: DebugInfo::None,
             lint_opts: Vec::new(),
-            force_warns: Vec::new(),
             lint_cap: None,
             describe_lints: false,
             output_types: OutputTypes(BTreeMap::new()),
@@ -1172,20 +1171,20 @@ pub fn get_cmd_lint_options(
     matches: &getopts::Matches,
     error_format: ErrorOutputType,
     debugging_opts: &DebuggingOptions,
-) -> (Vec<(String, lint::Level)>, bool, Option<lint::Level>, Vec<String>) {
+) -> (Vec<(String, lint::Level)>, bool, Option<lint::Level>) {
     let mut lint_opts_with_position = vec![];
     let mut describe_lints = false;
 
-    for level in [lint::Allow, lint::Warn, lint::Deny, lint::Forbid] {
-        for (passed_arg_pos, lint_name) in matches.opt_strs_pos(level.as_str()) {
-            let arg_pos = if let lint::Forbid = level {
-                // HACK: forbid is always specified last, so it can't be overridden.
-                // FIXME: remove this once <https://github.com/rust-lang/rust/issues/70819> is
-                // fixed and `forbid` works as expected.
-                usize::MAX
-            } else {
-                passed_arg_pos
-            };
+    if !debugging_opts.unstable_options && matches.opt_present("force-warns") {
+        early_error(
+            error_format,
+            "the `-Z unstable-options` flag must also be passed to enable \
+            the flag `--force-warns=lints`",
+        );
+    }
+
+    for level in [lint::Allow, lint::Warn, lint::ForceWarn, lint::Deny, lint::Forbid] {
+        for (arg_pos, lint_name) in matches.opt_strs_pos(level.as_str()) {
             if lint_name == "help" {
                 describe_lints = true;
             } else {
@@ -1206,18 +1205,7 @@ pub fn get_cmd_lint_options(
             .unwrap_or_else(|| early_error(error_format, &format!("unknown lint level: `{}`", cap)))
     });
 
-    if !debugging_opts.unstable_options && matches.opt_present("force-warns") {
-        early_error(
-            error_format,
-            "the `-Z unstable-options` flag must also be passed to enable \
-            the flag `--force-warns=lints`",
-        );
-    }
-
-    let force_warns =
-        matches.opt_strs("force-warns").into_iter().map(|name| name.replace('-', "_")).collect();
-
-    (lint_opts, describe_lints, lint_cap, force_warns)
+    (lint_opts, describe_lints, lint_cap)
 }
 
 /// Parses the `--color` flag.
@@ -1955,7 +1943,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         .unwrap_or_else(|e| early_error(error_format, &e[..]));
 
     let mut debugging_opts = DebuggingOptions::build(matches, error_format);
-    let (lint_opts, describe_lints, lint_cap, force_warns) =
+    let (lint_opts, describe_lints, lint_cap) =
         get_cmd_lint_options(matches, error_format, &debugging_opts);
 
     check_debug_option_stability(&debugging_opts, error_format, json_rendered);
@@ -2129,7 +2117,6 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         optimize: opt_level,
         debuginfo,
         lint_opts,
-        force_warns,
         lint_cap,
         describe_lints,
         output_types,

compiler/rustc_session/src/options.rs

@@ -135,7 +135,6 @@ top_level_options!(
         debuginfo: DebugInfo [TRACKED],
         lint_opts: Vec<(String, lint::Level)> [TRACKED_NO_CRATE_HASH],
         lint_cap: Option<lint::Level> [TRACKED_NO_CRATE_HASH],
-        force_warns: Vec<String> [TRACKED_NO_CRATE_HASH],
         describe_lints: bool [UNTRACKED],
         output_types: OutputTypes [TRACKED],
         search_paths: Vec<SearchPath> [UNTRACKED],

src/librustdoc/config.rs

@@ -632,7 +632,7 @@ impl Options {
         let show_type_layout = matches.opt_present("show-type-layout");
         let nocapture = matches.opt_present("nocapture");
 
-        let (lint_opts, describe_lints, lint_cap, _) =
+        let (lint_opts, describe_lints, lint_cap) =
             get_cmd_lint_options(matches, error_format, &debugging_opts);
 
         Ok(Options {

src/test/ui/lint/cli-lint-override.forbid_warn.stderr

@@ -0,0 +1,11 @@
+error: extern declarations without an explicit ABI are deprecated
+  --> $DIR/cli-lint-override.rs:12:1
+   |
+LL | extern fn foo() {}
+   | ^^^^^^^^^^^^^^^ ABI should be specified here
+   |
+   = note: requested on the command line with `-F missing-abi`
+   = help: the default ABI is C
+
+error: aborting due to previous error
+

src/test/ui/lint/cli-lint-override.force_warn_deny.stderr

@@ -0,0 +1,11 @@
+warning: extern declarations without an explicit ABI are deprecated
+  --> $DIR/cli-lint-override.rs:12:1
+   |
+LL | extern fn foo() {}
+   | ^^^^^^^^^^^^^^^ ABI should be specified here
+   |
+   = note: requested on the command line with `--force-warns missing-abi`
+   = help: the default ABI is C
+
+warning: 1 warning emitted
+

src/test/ui/lint/cli-lint-override.rs

@@ -0,0 +1,17 @@
+// Tests that subsequent lints specified via the command line override
+// each other, except for ForceWarn and Forbid, which cannot be overriden.
+//
+// revisions: warn_deny forbid_warn force_warn_deny
+//
+//[warn_deny] compile-flags: --warn missing_abi --deny missing_abi
+//[forbid_warn] compile-flags: --warn missing_abi --forbid missing_abi
+//[force_warn_deny] compile-flags: -Z unstable-options --force-warns missing_abi --allow missing_abi
+//[force_warn_deny] check-pass
+
+
+extern fn foo() {}
+//[warn_deny]~^ ERROR extern declarations without an explicit ABI are deprecated
+//[forbid_warn]~^^ ERROR extern declarations without an explicit ABI are deprecated
+//[force_warn_deny]~^^^ WARN extern declarations without an explicit ABI are deprecated
+
+fn main() {}

src/test/ui/lint/cli-lint-override.warn_deny.stderr

@@ -0,0 +1,11 @@
+error: extern declarations without an explicit ABI are deprecated
+  --> $DIR/cli-lint-override.rs:12:1
+   |
+LL | extern fn foo() {}
+   | ^^^^^^^^^^^^^^^ ABI should be specified here
+   |
+   = note: requested on the command line with `-D missing-abi`
+   = help: the default ABI is C
+
+error: aborting due to previous error
+

src/test/ui/lint/cli-unknown-force-warn.rs

@@ -0,0 +1,7 @@
+// Checks that rustc correctly errors when passed an invalid lint with
+// `--force-warns`. This is a regression test for issue #86958.
+//
+// compile-flags: -Z unstable-options --force-warns foo-qux
+// error-pattern: unknown lint: `foo_qux`
+
+fn main() {}

src/test/ui/lint/cli-unknown-force-warn.stderr

@@ -0,0 +1,15 @@
+error[E0602]: unknown lint: `foo_qux`
+   |
+   = note: requested on the command line with `--force-warns foo_qux`
+
+error[E0602]: unknown lint: `foo_qux`
+   |
+   = note: requested on the command line with `--force-warns foo_qux`
+
+error[E0602]: unknown lint: `foo_qux`
+   |
+   = note: requested on the command line with `--force-warns foo_qux`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0602`.