Revert "Prevent forbid from being ignored if overriden at the same level."

This reverts commit afa2a67.

Author: Mark-Simulacrum

compiler/rustc_lint/src/levels.rs

@@ -10,7 +10,6 @@ use rustc_hir as hir;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_hir::{intravisit, HirId};
 use rustc_middle::hir::map::Map;
-use rustc_middle::lint::LevelSource;
 use rustc_middle::lint::LintDiagnosticBuilder;
 use rustc_middle::lint::{struct_lint_level, LintLevelMap, LintLevelSets, LintSet, LintSource};
 use rustc_middle::ty::query::Providers;
@@ -97,44 +96,6 @@ impl<'s> LintLevelsBuilder<'s> {
         self.sets.list.push(LintSet::CommandLine { specs });
     }
 
-    /// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
-    /// (e.g. if a forbid was already inserted on the same scope), then emits a
-    /// diagnostic with no change to `specs`.
-    fn insert_spec(
-        &mut self,
-        specs: &mut FxHashMap<LintId, LevelSource>,
-        id: LintId,
-        (level, src): LevelSource,
-    ) {
-        if let Some((old_level, old_src)) = specs.get(&id) {
-            if old_level == &Level::Forbid && level != Level::Forbid {
-                let mut diag_builder = struct_span_err!(
-                    self.sess,
-                    src.span(),
-                    E0453,
-                    "{}({}) incompatible with previous forbid in same scope",
-                    level.as_str(),
-                    src.name(),
-                );
-                match *old_src {
-                    LintSource::Default => {}
-                    LintSource::Node(_, forbid_source_span, reason) => {
-                        diag_builder.span_label(forbid_source_span, "`forbid` level set here");
-                        if let Some(rationale) = reason {
-                            diag_builder.note(&rationale.as_str());
-                        }
-                    }
-                    LintSource::CommandLine(_, _) => {
-                        diag_builder.note("`forbid` lint level was set on command line");
-                    }
-                }
-                diag_builder.emit();
-                return;
-            }
-        }
-        specs.insert(id, (level, src));
-    }
-
     /// Pushes a list of AST lint attributes onto this context.
     ///
     /// This function will return a `BuilderPush` object which should be passed
@@ -149,7 +110,7 @@ impl<'s> LintLevelsBuilder<'s> {
     ///   `#[allow]`
     ///
     /// Don't forget to call `pop`!
-    pub(crate) fn push(
+    pub fn push(
         &mut self,
         attrs: &[ast::Attribute],
         store: &LintStore,
@@ -261,7 +222,7 @@ impl<'s> LintLevelsBuilder<'s> {
                         let src = LintSource::Node(name, li.span(), reason);
                         for &id in ids {
                             self.check_gated_lint(id, attr.span);
-                            self.insert_spec(&mut specs, id, (level, src));
+                            specs.insert(id, (level, src));
                         }
                     }
 
@@ -275,7 +236,7 @@ impl<'s> LintLevelsBuilder<'s> {
                                     reason,
                                 );
                                 for id in ids {
-                                    self.insert_spec(&mut specs, *id, (level, src));
+                                    specs.insert(*id, (level, src));
                                 }
                             }
                             Err((Some(ids), new_lint_name)) => {
@@ -312,7 +273,7 @@ impl<'s> LintLevelsBuilder<'s> {
                                     reason,
                                 );
                                 for id in ids {
-                                    self.insert_spec(&mut specs, *id, (level, src));
+                                    specs.insert(*id, (level, src));
                                 }
                             }
                             Err((None, _)) => {

compiler/rustc_middle/src/lint.rs

@@ -9,7 +9,7 @@ use rustc_session::lint::{builtin, Level, Lint, LintId};
 use rustc_session::{DiagnosticMessageId, Session};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
-use rustc_span::{symbol, Span, Symbol, DUMMY_SP};
+use rustc_span::{Span, Symbol};
 
 /// How a lint level was set.
 #[derive(Clone, Copy, PartialEq, Eq, HashStable)]
@@ -27,24 +27,6 @@ pub enum LintSource {
     CommandLine(Symbol, Level),
 }
 
-impl LintSource {
-    pub fn name(&self) -> Symbol {
-        match *self {
-            LintSource::Default => symbol::kw::Default,
-            LintSource::Node(name, _, _) => name,
-            LintSource::CommandLine(name, _) => name,
-        }
-    }
-
-    pub fn span(&self) -> Span {
-        match *self {
-            LintSource::Default => DUMMY_SP,
-            LintSource::Node(_, span, _) => span,
-            LintSource::CommandLine(_, _) => DUMMY_SP,
-        }
-    }
-}
-
 pub type LevelSource = (Level, LintSource);
 
 pub struct LintLevelSets {