rustc_errors: handle force_warn only through DiagnosticId::Lint.

compiler/rustc_errors/src/lib.rs

@@ -632,27 +632,15 @@ impl Handler {
 
     /// Construct a builder at the `Warning` level at the given `span` and with the `msg`.
     ///
-    /// The builder will be canceled if warnings cannot be emitted.
+    /// Attempting to `.emit()` the builder will only emit if either:
+    /// * `can_emit_warnings` is `true`
+    /// * `is_force_warn` was set in `DiagnosticId::Lint`
     pub fn struct_span_warn(&self, span: impl Into<MultiSpan>, msg: &str) -> DiagnosticBuilder<'_> {
         let mut result = self.struct_warn(msg);
         result.set_span(span);
         result
     }
 
-    /// Construct a builder at the `Warning` level at the given `span` and with the `msg`.
-    ///
-    /// This will "force" the warning meaning it will not be canceled even
-    /// if warnings cannot be emitted.
-    pub fn struct_span_force_warn(
-        &self,
-        span: impl Into<MultiSpan>,
-        msg: &str,
-    ) -> DiagnosticBuilder<'_> {
-        let mut result = self.struct_force_warn(msg);
-        result.set_span(span);
-        result
-    }
-
     /// Construct a builder at the `Allow` level at the given `span` and with the `msg`.
     pub fn struct_span_allow(
         &self,
@@ -679,20 +667,10 @@ impl Handler {
 
     /// Construct a builder at the `Warning` level with the `msg`.
     ///
-    /// The builder will be canceled if warnings cannot be emitted.
+    /// Attempting to `.emit()` the builder will only emit if either:
+    /// * `can_emit_warnings` is `true`
+    /// * `is_force_warn` was set in `DiagnosticId::Lint`
     pub fn struct_warn(&self, msg: &str) -> DiagnosticBuilder<'_> {
-        let mut result = DiagnosticBuilder::new(self, Level::Warning, msg);
-        if !self.flags.can_emit_warnings {
-            result.cancel();
-        }
-        result
-    }
-
-    /// Construct a builder at the `Warning` level with the `msg`.
-    ///
-    /// This will "force" a warning meaning it will not be canceled even
-    /// if warnings cannot be emitted.
-    pub fn struct_force_warn(&self, msg: &str) -> DiagnosticBuilder<'_> {
         DiagnosticBuilder::new(self, Level::Warning, msg)
     }
 

compiler/rustc_middle/src/lint.rs

@@ -314,10 +314,8 @@ pub fn struct_lint_level<'s, 'd>(
                     return;
                 }
             }
-            (Level::Warn, Some(span)) => sess.struct_span_warn(span, ""),
+            (Level::Warn | Level::ForceWarn, Some(span)) => sess.struct_span_warn(span, ""),
-            (Level::Warn, None) => sess.struct_warn(""),
+            (Level::Warn | Level::ForceWarn, None) => sess.struct_warn(""),
-            (Level::ForceWarn, Some(span)) => sess.struct_span_force_warn(span, ""),
-            (Level::ForceWarn, None) => sess.struct_force_warn(""),
             (Level::Deny | Level::Forbid, Some(span)) => {
                 let mut builder = sess.diagnostic().struct_err_lint("");
                 builder.set_span(span);

compiler/rustc_session/src/session.rs

@@ -306,13 +306,6 @@ impl Session {
     pub fn struct_span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> DiagnosticBuilder<'_> {
         self.diagnostic().struct_span_warn(sp, msg)
     }
-    pub fn struct_span_force_warn<S: Into<MultiSpan>>(
-        &self,
-        sp: S,
-        msg: &str,
-    ) -> DiagnosticBuilder<'_> {
-        self.diagnostic().struct_span_force_warn(sp, msg)
-    }
     pub fn struct_span_warn_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -324,9 +317,6 @@ impl Session {
     pub fn struct_warn(&self, msg: &str) -> DiagnosticBuilder<'_> {
         self.diagnostic().struct_warn(msg)
     }
-    pub fn struct_force_warn(&self, msg: &str) -> DiagnosticBuilder<'_> {
-        self.diagnostic().struct_force_warn(msg)
-    }
     pub fn struct_span_allow<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> DiagnosticBuilder<'_> {
         self.diagnostic().struct_span_allow(sp, msg)
     }