New force_warn diagnostic builder and ensure cap-lints doesn't reduce force_warn level

3 files changed, 39 insertions, 14 deletions

diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index c5399282a1e..a5e11541c8b 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -521,12 +521,24 @@ impl Handler {
     }
 
     /// Construct a builder at the `Warning` level at the given `span` and with the `msg`.
+    /// Cancel the builder if warnings cannot be emitted
     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`.
+    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,
@@ -552,6 +564,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Warning` level with the `msg`.
+    /// Cancel the builder if warnings cannot be emitted
     pub fn struct_warn(&self, msg: &str) -> DiagnosticBuilder<'_> {
         let mut result = DiagnosticBuilder::new(self, Level::Warning, msg);
         if !self.flags.can_emit_warnings {
@@ -560,6 +573,11 @@ impl Handler {
         result
     }
 
+    /// Construct a builder at the `Warning` level with the `msg`.
+    pub fn struct_force_warn(&self, msg: &str) -> DiagnosticBuilder<'_> {
+        DiagnosticBuilder::new(self, Level::Warning, msg)
+    }
+
     /// Construct a builder at the `Allow` level with the `msg`.
     pub fn struct_allow(&self, msg: &str) -> DiagnosticBuilder<'_> {
         DiagnosticBuilder::new(self, Level::Allow, msg)
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 71cf5b2249c..b5eab8be17f 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -108,8 +108,13 @@ impl LintLevelSets {
             }
         }
 
-        // Ensure that we never exceed the `--cap-lints` argument.
-        level = cmp::min(level, self.lint_cap);
+        // Ensure that we never exceed the `--cap-lints` argument
+        // unless the source is a --force-warn
+        level = if let LintLevelSource::CommandLine(_, Level::ForceWarn) = src {
+            level
+        } else {
+            cmp::min(level, self.lint_cap)
+        };
 
         if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
             // Ensure that we never exceed driver level.
@@ -257,22 +262,14 @@ pub fn struct_lint_level<'s, 'd>(
                     } else {
                         sess.struct_allow("")
                     }
-                } else if is_force_warn {
-                    let mut err = if let Some(span) = span {
-                        sess.struct_span_warn(span, "")
-                    } else {
-                        sess.struct_warn("")
-                    };
-                    // Ensure force-warn warns even if the diagnostic has
-                    // been canceled for reasons like `--cap-lints`
-                    err.level = rustc_errors::Level::Warning;
-                    err
                 } else {
                     return;
                 }
             }
-            (Level::Warn | Level::ForceWarn, Some(span)) => sess.struct_span_warn(span, ""),
-            (Level::Warn | Level::ForceWarn, None) => sess.struct_warn(""),
+            (Level::Warn, Some(span)) => sess.struct_span_warn(span, ""),
+            (Level::Warn, 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)) => sess.struct_span_err(span, ""),
             (Level::Deny | Level::Forbid, None) => sess.struct_err(""),
         };
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 2bcb7c94d53..f6b7797c2e3 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -369,6 +369,13 @@ 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,
@@ -380,6 +387,9 @@ 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)
     }