use diagnostic-mutating style for note_type_err too

that is much cleaner than the `type_err!` style I used earlier.

Author: Ariel Ben-Yehuda

src/librustc/infer/error_reporting.rs

@@ -521,25 +521,25 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
-    pub fn report_and_explain_type_error_with_code(&self,
-                                                   origin: TypeOrigin,
-                                                   values: Option<ValuePairs<'tcx>>,
-                                                   terr: &TypeError<'tcx>,
-                                                   message: &str,
-                                                   code: &str)
-                                                   -> DiagnosticBuilder<'tcx>
+    pub fn note_type_err(&self,
+                         diag: &mut DiagnosticBuilder<'tcx>,
+                         origin: TypeOrigin,
+                         values: Option<ValuePairs<'tcx>>,
+                         terr: &TypeError<'tcx>)
     {
         let expected_found = match values {
             None => None,
             Some(values) => match self.values_str(&values) {
                 Some((expected, found)) => Some((expected, found)),
-                None => return self.tcx.sess.diagnostic().struct_dummy() /* derived error */
+                None => {
+                    // Derived error. Cancel the emitter.
+                    self.tcx.sess.diagnostic().cancel(diag);
+                    return
+                }
             }
         };
 
         let span = origin.span();
-        let mut err = self.tcx.sess.struct_span_err_with_code(
-            span, message, code);
 
         let mut is_simple_error = false;
 
@@ -551,21 +551,19 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             };
 
             if !is_simple_error || check_old_school() {
-                err.note_expected_found(&"type", &expected, &found);
+                diag.note_expected_found(&"type", &expected, &found);
             }
         }
 
         if !is_simple_error && check_old_school() {
-            err.span_note(span, &format!("{}", terr));
+            diag.span_note(span, &format!("{}", terr));
         } else {
-            err.span_label(span, &terr);
+            diag.span_label(span, &terr);
         }
 
-        self.note_error_origin(&mut err, &origin);
-        self.check_and_note_conflicting_crates(&mut err, terr, span);
-        self.tcx.note_and_explain_type_err(&mut err, terr, span);
-
-        err
+        self.note_error_origin(diag, &origin);
+        self.check_and_note_conflicting_crates(diag, terr, span);
+        self.tcx.note_and_explain_type_err(diag, terr, span);
     }
 
     pub fn report_and_explain_type_error(&self,
@@ -574,8 +572,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                                          -> DiagnosticBuilder<'tcx>
     {
         // FIXME: do we want to use a different error code for each origin?
-        let failure_str = trace.origin.as_failure_str();
-        type_err!(self, trace.origin, Some(trace.values), terr, E0308, "{}", failure_str)
+        let mut diag = struct_span_err!(
+            self.tcx.sess, trace.origin.span(), E0308,
+            "{}", trace.origin.as_failure_str()
+        );
+        self.note_type_err(&mut diag, trace.origin, Some(trace.values), terr);
+        diag
     }
 
     /// Returns a string of the form "expected `{}`, found `{}`".

src/librustc/macros.rs

@@ -59,16 +59,3 @@ macro_rules! span_bug {
         $crate::session::span_bug_fmt(file!(), line!(), $span, format_args!($($message)*))
     })
 }
-
-#[macro_export]
-macro_rules! type_err {
-    ($infcx:expr, $origin: expr, $values: expr, $terr: expr, $code:ident, $($message:tt)*) => ({
-        __diagnostic_used!($code);
-        $infcx.report_and_explain_type_error_with_code(
-            $origin,
-            $values,
-            &$terr,
-            &format!($($message)*),
-            stringify!($code))
-    })
-}

src/librustc/traits/error_reporting.rs

@@ -157,14 +157,11 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 }
             }
 
-            let mut diag = type_err!(
-                self,
-                origin,
-                values,
-                err,
-                E0271,
-                "type mismatch resolving `{}`",
-                predicate);
+            let mut diag = struct_span_err!(
+                self.tcx.sess, origin.span(), E0271,
+                "type mismatch resolving `{}`", predicate
+            );
+            self.note_type_err(&mut diag, origin, values, err);
             self.note_obligation_cause(&mut diag, obligation);
             diag.emit();
         });

src/librustc_typeck/check/compare_method.rs

@@ -325,13 +325,19 @@ pub fn compare_impl_method<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
             debug!("sub_types failed: impl ty {:?}, trait ty {:?}",
                    impl_fty,
                    trait_fty);
-            let values = Some(infer::ValuePairs::Types(ExpectedFound {
-                expected: trait_fty,
-                found: impl_fty
-            }));
-            type_err!(infcx, origin, values, terr, E0053,
-                      "method `{}` has an incompatible type for trait",
-                      trait_m.name).emit();
+
+            let mut diag = struct_span_err!(
+                tcx.sess, origin.span(), E0053,
+                "method `{}` has an incompatible type for trait", trait_m.name
+            );
+            infcx.note_type_err(
+                &mut diag, origin,
+                Some(infer::ValuePairs::Types(ExpectedFound {
+                    expected: trait_fty,
+                    found: impl_fty
+                })), &terr
+            );
+            diag.emit();
             return
         }
 
@@ -476,13 +482,19 @@ pub fn compare_const_impl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
             debug!("checking associated const for compatibility: impl ty {:?}, trait ty {:?}",
                    impl_ty,
                    trait_ty);
-            let values = Some(infer::ValuePairs::Types(ExpectedFound {
-                expected: trait_ty,
-                found: impl_ty
-            }));
-            type_err!(infcx, origin, values, terr, E0326,
-                      "implemented const `{}` has an incompatible type for \
-                      trait", trait_c.name).emit();
+            let mut diag = struct_span_err!(
+                tcx.sess, origin.span(), E0326,
+                "implemented const `{}` has an incompatible type for trait",
+                trait_c.name
+            );
+            infcx.note_type_err(
+                &mut diag, origin,
+                Some(infer::ValuePairs::Types(ExpectedFound {
+                    expected: trait_ty,
+                    found: impl_ty
+                })), &terr
+            );
+            diag.emit();
         }
     });
 }