Force warn on lint groups as well

compiler/rustc_lint/src/context.rs

@@ -334,8 +334,14 @@ impl LintStore {
         }
     }
 
-    /// Checks the validity of lint names derived from the command line
-    pub fn check_lint_name_cmdline(&self, sess: &Session, lint_name: &str, level: Level) {
+    /// Checks the validity of lint names derived from the command line. Returns
+    /// true if the lint is valid, false otherwise.
+    pub fn check_lint_name_cmdline(
+        &self,
+        sess: &Session,
+        lint_name: &str,
+        level: Option<Level>,
+    ) -> bool {
         let db = match self.check_lint_name(lint_name, None) {
             CheckLintNameResult::Ok(_) => None,
             CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
@@ -361,18 +367,23 @@ impl LintStore {
         };
 
         if let Some(mut db) = db {
-            let msg = format!(
-                "requested on the command line with `{} {}`",
-                match level {
-                    Level::Allow => "-A",
-                    Level::Warn => "-W",
-                    Level::Deny => "-D",
-                    Level::Forbid => "-F",
-                },
-                lint_name
-            );
-            db.note(&msg);
+            if let Some(level) = level {
+                let msg = format!(
+                    "requested on the command line with `{} {}`",
+                    match level {
+                        Level::Allow => "-A",
+                        Level::Warn => "-W",
+                        Level::Deny => "-D",
+                        Level::Forbid => "-F",
+                    },
+                    lint_name
+                );
+                db.note(&msg);
+            }
             db.emit();
+            false
+        } else {
+            true
         }
     }
 

compiler/rustc_lint/src/levels.rs

@@ -88,7 +88,7 @@ impl<'s> LintLevelsBuilder<'s> {
         self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
 
         for &(ref lint_name, level) in &sess.opts.lint_opts {
-            store.check_lint_name_cmdline(sess, &lint_name, level);
+            store.check_lint_name_cmdline(sess, &lint_name, Some(level));
             let orig_level = level;
 
             // If the cap is less than this specified level, e.g., if we've got
@@ -110,8 +110,13 @@ impl<'s> LintLevelsBuilder<'s> {
         }
 
         for lint_name in &sess.opts.force_warns {
-            store.check_lint_name_cmdline(sess, &lint_name, Level::Allow); // FIXME level is wrong
-            self.sets.force_warns.insert(lint_name.to_uppercase());
+            let valid = store.check_lint_name_cmdline(sess, lint_name, None);
+            if valid {
+                let lints = store
+                    .find_lints(lint_name)
+                    .unwrap_or_else(|_| bug!("A valid lint failed to produce a lint ids"));
+                self.sets.force_warns.extend(&lints);
+            }
         }
 
         self.sets.list.push(LintSet::CommandLine { specs });

compiler/rustc_middle/src/lint.rs

@@ -60,7 +60,7 @@ pub type LevelAndSource = (Level, LintLevelSource);
 pub struct LintLevelSets {
     pub list: Vec<LintSet>,
     pub lint_cap: Level,
-    pub force_warns: FxHashSet<String>,
+    pub force_warns: FxHashSet<LintId>,
 }
 
 #[derive(Debug)]
@@ -94,7 +94,7 @@ impl LintLevelSets {
         sess: &Session,
     ) -> LevelAndSource {
         // Check whether we should always warn
-        if self.force_warns.contains(lint.name) {
+        if self.force_warns.contains(&LintId::of(lint)) {
             return (Level::Warn, LintLevelSource::ForceWarn(Symbol::intern(lint.name)));
         }
 

compiler/rustc_session/src/config.rs

@@ -1164,6 +1164,7 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
 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>) {
     let mut lint_opts_with_position = vec![];
     let mut describe_lints = false;
@@ -1198,6 +1199,14 @@ 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");
 
     (lint_opts, describe_lints, lint_cap, force_warns)
@@ -1937,10 +1946,10 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let crate_types = parse_crate_types_from_list(unparsed_crate_types)
         .unwrap_or_else(|e| early_error(error_format, &e[..]));
 
-    let (lint_opts, describe_lints, lint_cap, force_warns) =
-        get_cmd_lint_options(matches, error_format);
-
     let mut debugging_opts = DebuggingOptions::build(matches, error_format);
+    let (lint_opts, describe_lints, lint_cap, force_warns) =
+        get_cmd_lint_options(matches, error_format, &debugging_opts);
+
     check_debug_option_stability(&debugging_opts, error_format, json_rendered);
 
     if !debugging_opts.unstable_options && json_unused_externs {

src/librustdoc/config.rs

@@ -635,7 +635,8 @@ impl Options {
         let generate_redirect_map = matches.opt_present("generate-redirect-map");
         let show_type_layout = matches.opt_present("show-type-layout");
 
-        let (lint_opts, describe_lints, lint_cap) = get_cmd_lint_options(matches, error_format);
+        let (lint_opts, describe_lints, lint_cap, _) =
+            get_cmd_lint_options(matches, error_format, &debugging_opts);
 
         Ok(Options {
             input,

src/librustdoc/lib.rs

@@ -510,6 +510,14 @@ fn opts() -> Vec<RustcOptGroup> {
                 "LEVEL",
             )
         }),
+        unstable("force-warns", |o| {
+            o.optopt(
+                "",
+                "force-warns",
+                "Lints that will warn even if allowed somewhere else",
+                "LINTS",
+            )
+        }),
         unstable("index-page", |o| {
             o.optopt("", "index-page", "Markdown file to be used as index page", "PATH")
         }),

src/test/ui/lint/force-warn/force-allowed-by-default-lint.stderr

@@ -1,5 +1,5 @@
 warning: hidden lifetime parameters in types are deprecated
-  --> $DIR/force-allow-by-default.rs:8:12
+  --> $DIR/force-allowed-by-default-lint.rs:8:12
    |
 LL | fn foo(x: &Foo) {}
    |            ^^^- help: indicate the anonymous lifetime: `<'_>`

src/test/ui/lint/force-warn/force-lint-allow-all-warnings.stderr

@@ -1,5 +1,5 @@
 warning: function is never used: `dead_function`
-  --> $DIR/force-allow-all-warnings.rs:6:4
+  --> $DIR/force-lint-allow-all-warnings.rs:6:4
    |
 LL | fn dead_function() {}
    |    ^^^^^^^^^^^^^

src/test/ui/lint/force-warn/force-lint-group-allow-all-warnings.rs

@@ -0,0 +1,9 @@
+// compile-flags: --force-warns nonstandard_style
+// check-pass
+
+#![allow(warnings)]
+
+pub fn FUNCTION() {}
+//~^ WARN function `FUNCTION` should have a snake case name
+
+fn main() {}

src/test/ui/lint/force-warn/force-lint-group-allow-all-warnings.stderr

@@ -0,0 +1,10 @@
+warning: function `FUNCTION` should have a snake case name
+  --> $DIR/force-lint-group-allow-all-warnings.rs:6:8
+   |
+LL | pub fn FUNCTION() {}
+   |        ^^^^^^^^ help: convert the identifier to snake case: `function`
+   |
+   = note: Warning forced by `force-warns` commandline option
+
+warning: 1 warning emitted
+

src/test/ui/lint/force-warn/force-lint-in-allowed-group.stderr

@@ -0,0 +1,12 @@
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/force-lint-in-allowed-group.rs:8:25
+   |
+LL | pub fn function(_x: Box<SomeTrait>) {}
+   |                         ^^^^^^^^^ help: use `dyn`: `dyn SomeTrait`
+   |
+   = note: Warning forced by `force-warns` commandline option
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
+   = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
+
+warning: 1 warning emitted
+

src/test/ui/lint/force-warn/force-warn-group-allow-warning.rs

@@ -0,0 +1,12 @@
+// compile-flags: --force-warns rust_2018_idioms
+// check-pass
+
+#![allow(bare_trait_objects)]
+
+pub trait SomeTrait {}
+
+pub fn function(_x: Box<SomeTrait>) {}
+//~^ WARN trait objects without an explicit `dyn` are deprecated
+//~| WARN this was previously accepted by the compiler
+
+fn main() {}

src/test/ui/lint/force-warn/force-warn-group-allow-warning.stderr

@@ -0,0 +1,12 @@
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/force-warn-group-allow-warning.rs:8:25
+   |
+LL | pub fn function(_x: Box<SomeTrait>) {}
+   |                         ^^^^^^^^^ help: use `dyn`: `dyn SomeTrait`
+   |
+   = note: Warning forced by `force-warns` commandline option
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
+   = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
+
+warning: 1 warning emitted
+

src/test/ui/lint/force-warn/force-warn-group.rs

@@ -1,4 +1,3 @@
-// ignore-test
 // compile-flags: --force-warns rust_2018_idioms
 // check-pass
 

src/test/ui/lint/force-warn/force-warn-group.stderr

@@ -1,5 +1,5 @@
 warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/force-allowed-group.rs:8:25
+  --> $DIR/force-warn-group.rs:8:25
    |
 LL | pub fn function(_x: Box<SomeTrait>) {}
    |                         ^^^^^^^^^ help: use `dyn`: `dyn SomeTrait`