Small cleanup: remove unneeded result (#15256)

Author: weihanglo

src/cargo/core/compiler/job_queue/job_state.rs

@@ -125,12 +125,11 @@ impl<'a, 'gctx> JobState<'a, 'gctx> {
     }
 
     /// See [`Message::Warning`].
-    pub fn warning(&self, warning: String) -> CargoResult<()> {
+    pub fn warning(&self, warning: String) {
         self.messages.push_bounded(Message::Warning {
             id: self.id,
             warning,
         });
-        Ok(())
     }
 
     /// A method used to signal to the coordinator thread that the rmeta file

src/cargo/core/compiler/mod.rs

@@ -449,7 +449,7 @@ fn rustc(
 
             if let Err(e) = result {
                 if let Some(diagnostic) = failed_scrape_diagnostic {
-                    state.warning(diagnostic)?;
+                    state.warning(diagnostic);
                 }
 
                 return Err(e);
@@ -920,7 +920,7 @@ fn rustdoc(build_runner: &mut BuildRunner<'_, '_>, unit: &Unit) -> CargoResult<W
 
         if let Err(e) = result {
             if let Some(diagnostic) = failed_scrape_diagnostic {
-                state.warning(diagnostic)?;
+                state.warning(diagnostic);
             }
 
             return Err(e);