rustc_error: make ErrorReported impossible to construct

There are a few places were we have to construct it, though, and a few
places that are more invasive to change. To do this, we create a
constructor with a long obvious name.

9 files changed, 48 insertions, 38 deletions

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 47de4c9be26..50a3df21a3b 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -157,7 +157,7 @@ impl BoxPointers {
             if let GenericArgKind::Type(leaf_ty) = leaf.unpack() {
                 if leaf_ty.is_box() {
                     cx.struct_span_lint(BOX_POINTERS, span, |lint| {
-                        lint.build(&format!("type uses owned (Box type) pointers: {}", ty)).emit()
+                        lint.build(&format!("type uses owned (Box type) pointers: {}", ty)).emit();
                     });
                 }
             }
@@ -318,7 +318,7 @@ impl UnsafeCode {
         &self,
         cx: &EarlyContext<'_>,
         span: Span,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         // This comes from a macro that has `#[allow_internal_unsafe]`.
         if span.allows_unsafe() {
@@ -350,7 +350,7 @@ impl EarlyLintPass for UnsafeCode {
                                                macros using unsafe without triggering \
                                                the `unsafe_code` lint at their call site",
                 )
-                .emit()
+                .emit();
             });
         }
     }
@@ -360,7 +360,7 @@ impl EarlyLintPass for UnsafeCode {
             // Don't warn about generated blocks; that'll just pollute the output.
             if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
                 self.report_unsafe(cx, blk.span, |lint| {
-                    lint.build("usage of an `unsafe` block").emit()
+                    lint.build("usage of an `unsafe` block").emit();
                 });
             }
         }
@@ -370,12 +370,12 @@ impl EarlyLintPass for UnsafeCode {
         match it.kind {
             ast::ItemKind::Trait(box ast::Trait { unsafety: ast::Unsafe::Yes(_), .. }) => self
                 .report_unsafe(cx, it.span, |lint| {
-                    lint.build("declaration of an `unsafe` trait").emit()
+                    lint.build("declaration of an `unsafe` trait").emit();
                 }),
 
             ast::ItemKind::Impl(box ast::Impl { unsafety: ast::Unsafe::Yes(_), .. }) => self
                 .report_unsafe(cx, it.span, |lint| {
-                    lint.build("implementation of an `unsafe` trait").emit()
+                    lint.build("implementation of an `unsafe` trait").emit();
                 }),
 
             ast::ItemKind::Fn(..) => {
@@ -450,7 +450,9 @@ impl EarlyLintPass for UnsafeCode {
                 FnCtxt::Assoc(_) if body.is_none() => "declaration of an `unsafe` method",
                 FnCtxt::Assoc(_) => "implementation of an `unsafe` method",
             };
-            self.report_unsafe(cx, span, |lint| lint.build(msg).emit());
+            self.report_unsafe(cx, span, |lint| {
+                lint.build(msg).emit();
+            });
         }
     }
 }
@@ -559,7 +561,7 @@ impl MissingDoc {
                 MISSING_DOCS,
                 cx.tcx.sess.source_map().guess_head_span(sp),
                 |lint| {
-                    lint.build(&format!("missing documentation for {} {}", article, desc)).emit()
+                    lint.build(&format!("missing documentation for {} {}", article, desc)).emit();
                 },
             );
         }
@@ -777,7 +779,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
                     "type could implement `Copy`; consider adding `impl \
                           Copy`",
                 )
-                .emit()
+                .emit();
             })
         }
     }
@@ -858,7 +860,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations {
                      or a manual implementation",
                     cx.tcx.def_path_str(debug)
                 ))
-                .emit()
+                .emit();
             });
         }
     }
@@ -1278,7 +1280,9 @@ impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
             if to_mt == hir::Mutability::Mut && from_mt == hir::Mutability::Not {
                 let msg = "transmuting &T to &mut T is undefined behavior, \
                     even if the reference is unused, consider instead using an UnsafeCell";
-                cx.struct_span_lint(MUTABLE_TRANSMUTES, expr.span, |lint| lint.build(msg).emit());
+                cx.struct_span_lint(MUTABLE_TRANSMUTES, expr.span, |lint| {
+                    lint.build(msg).emit();
+                });
             }
         }
 
@@ -1328,7 +1332,7 @@ impl<'tcx> LateLintPass<'tcx> for UnstableFeatures {
             if let Some(items) = attr.meta_item_list() {
                 for item in items {
                     cx.struct_span_lint(UNSTABLE_FEATURES, item.span(), |lint| {
-                        lint.build("unstable feature").emit()
+                        lint.build("unstable feature").emit();
                     });
                 }
             }
@@ -1680,7 +1684,7 @@ impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
                                 or lifetime parameters",
                             predicate_kind_name, predicate
                         ))
-                        .emit()
+                        .emit();
                     });
                 }
             }
@@ -1915,7 +1919,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems {
         let attrs = cx.tcx.hir().attrs(it.hir_id());
         if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) {
             cx.struct_span_lint(UNNAMEABLE_TEST_ITEMS, attr.span, |lint| {
-                lint.build("cannot test inner items").emit()
+                lint.build("cannot test inner items").emit();
             });
         }
     }
@@ -2040,7 +2044,7 @@ impl KeywordIdents {
                     format!("r#{}", ident),
                     Applicability::MachineApplicable,
                 )
-                .emit()
+                .emit();
         });
     }
 }
@@ -3055,7 +3059,7 @@ impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
                                 "this signature doesn't match the previous declaration",
                             )
                             .note_expected_found(&"", expected_str, &"", found_str)
-                            .emit()
+                            .emit();
                         },
                     );
                 }
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index d3c019ad70e..882fa4496ca 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -593,7 +593,7 @@ pub trait LintContext: Sized {
         &self,
         lint: &'static Lint,
         span: Option<impl Into<MultiSpan>>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
         diagnostic: BuiltinLintDiagnostics,
     ) {
         self.lookup(lint, span, |lint| {
@@ -840,19 +840,23 @@ pub trait LintContext: Sized {
         &self,
         lint: &'static Lint,
         span: Option<S>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     );
 
     fn struct_span_lint<S: Into<MultiSpan>>(
         &self,
         lint: &'static Lint,
         span: S,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         self.lookup(lint, Some(span), decorate);
     }
     /// Emit a lint at the appropriate level, with no associated span.
-    fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
+    fn lint(
+        &self,
+        lint: &'static Lint,
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
+    ) {
         self.lookup(lint, None as Option<Span>, decorate);
     }
 }
@@ -893,7 +897,7 @@ impl LintContext for LateContext<'_> {
         &self,
         lint: &'static Lint,
         span: Option<S>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         let hir_id = self.last_node_with_lint_attrs;
 
@@ -920,7 +924,7 @@ impl LintContext for EarlyContext<'_> {
         &self,
         lint: &'static Lint,
         span: Option<S>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
     }
diff --git a/compiler/rustc_lint/src/early.rs b/compiler/rustc_lint/src/early.rs
index e9b7620bf1d..7447f9f64b7 100644
--- a/compiler/rustc_lint/src/early.rs
+++ b/compiler/rustc_lint/src/early.rs
@@ -45,7 +45,9 @@ impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
             self.context.lookup_with_diagnostics(
                 lint_id.lint,
                 Some(span),
-                |lint| lint.build(&msg).emit(),
+                |lint| {
+                    lint.build(&msg).emit();
+                },
                 diagnostic,
             );
         }
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index 0d790e38206..99a5720832e 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -652,7 +652,7 @@ impl<'s> LintLevelsBuilder<'s> {
         &self,
         lint: &'static Lint,
         span: Option<MultiSpan>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         let (level, src) = self.lint_level(lint);
         struct_lint_level(self.sess, lint, level, src, span, decorate)
diff --git a/compiler/rustc_lint/src/non_ascii_idents.rs b/compiler/rustc_lint/src/non_ascii_idents.rs
index 264a80339cc..6182d2b10ed 100644
--- a/compiler/rustc_lint/src/non_ascii_idents.rs
+++ b/compiler/rustc_lint/src/non_ascii_idents.rs
@@ -180,13 +180,13 @@ impl EarlyLintPass for NonAsciiIdents {
             }
             has_non_ascii_idents = true;
             cx.struct_span_lint(NON_ASCII_IDENTS, sp, |lint| {
-                lint.build("identifier contains non-ASCII characters").emit()
+                lint.build("identifier contains non-ASCII characters").emit();
             });
             if check_uncommon_codepoints
                 && !symbol_str.chars().all(GeneralSecurityProfile::identifier_allowed)
             {
                 cx.struct_span_lint(UNCOMMON_CODEPOINTS, sp, |lint| {
-                    lint.build("identifier contains uncommon Unicode codepoints").emit()
+                    lint.build("identifier contains uncommon Unicode codepoints").emit();
                 })
             }
         }
@@ -337,7 +337,7 @@ impl EarlyLintPass for NonAsciiIdents {
                             let char_info = format!("'{}' (U+{:04X})", ch, ch as u32);
                             note += &char_info;
                         }
-                        lint.build(&message).note(&note).note("please recheck to make sure their usages are indeed what you want").emit()
+                        lint.build(&message).note(&note).note("please recheck to make sure their usages are indeed what you want").emit();
                     });
                 }
             }
diff --git a/compiler/rustc_lint/src/noop_method_call.rs b/compiler/rustc_lint/src/noop_method_call.rs
index 39b5b7afdae..5d734fd2ba7 100644
--- a/compiler/rustc_lint/src/noop_method_call.rs
+++ b/compiler/rustc_lint/src/noop_method_call.rs
@@ -102,7 +102,7 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
             let method = &call.ident.name;
             let message =
                 format!("call to `.{}()` on a reference in this situation does nothing", &method,);
-            lint.build(&message).span_label(span, "unnecessary method call").note(&note).emit()
+            lint.build(&message).span_label(span, "unnecessary method call").note(&note).emit();
         });
     }
 }
diff --git a/compiler/rustc_lint/src/traits.rs b/compiler/rustc_lint/src/traits.rs
index 4c7f3482776..5b6997bf0ee 100644
--- a/compiler/rustc_lint/src/traits.rs
+++ b/compiler/rustc_lint/src/traits.rs
@@ -113,7 +113,7 @@ impl<'tcx> LateLintPass<'tcx> for DropTraitConstraints {
                         predicate,
                         cx.tcx.def_path_str(needs_drop)
                     );
-                    lint.build(&msg).emit()
+                    lint.build(&msg).emit();
                 });
             }
         }
@@ -135,7 +135,7 @@ impl<'tcx> LateLintPass<'tcx> for DropTraitConstraints {
                         instead using `{}` to detect whether a type is trivially dropped",
                         cx.tcx.def_path_str(needs_drop)
                     );
-                    lint.build(&msg).emit()
+                    lint.build(&msg).emit();
                 });
             }
         }
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index ed5578c754d..c95905b9b18 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -441,7 +441,7 @@ fn lint_uint_literal<'tcx>(
                     min,
                     max,
                 ))
-                .emit()
+                .emit();
         });
     }
 }
@@ -502,7 +502,7 @@ impl<'tcx> LateLintPass<'tcx> for TypeLimits {
             hir::ExprKind::Binary(binop, ref l, ref r) => {
                 if is_comparison(binop) && !check_limits(cx, binop, &l, &r) {
                     cx.struct_span_lint(UNUSED_COMPARISONS, e.span, |lint| {
-                        lint.build("comparison is useless due to type limits").emit()
+                        lint.build("comparison is useless due to type limits").emit();
                     });
                 }
             }
@@ -1382,7 +1382,7 @@ impl<'tcx> LateLintPass<'tcx> for VariantSizeDifferences {
                                           larger ({} bytes) than the next largest",
                             largest
                         ))
-                        .emit()
+                        .emit();
                     },
                 );
             }
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
index abe34a8a39f..91b72f1d2b1 100644
--- a/compiler/rustc_lint/src/unused.rs
+++ b/compiler/rustc_lint/src/unused.rs
@@ -170,7 +170,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
 
         if !(type_permits_lack_of_use || fn_warned || op_warned) {
             cx.struct_span_lint(UNUSED_RESULTS, s.span, |lint| {
-                lint.build(&format!("unused result of type `{}`", ty)).emit()
+                lint.build(&format!("unused result of type `{}`", ty)).emit();
             });
         }
 
@@ -368,9 +368,9 @@ impl<'tcx> LateLintPass<'tcx> for PathStatements {
                         } else {
                             lint.span_help(s.span, "use `drop` to clarify the intent");
                         }
-                        lint.emit()
+                        lint.emit();
                     } else {
-                        lint.build("path statement with no effect").emit()
+                        lint.build("path statement with no effect").emit();
                     }
                 });
             }
@@ -1111,7 +1111,7 @@ impl UnusedImportBraces {
             };
 
             cx.struct_span_lint(UNUSED_IMPORT_BRACES, item.span, |lint| {
-                lint.build(&format!("braces around {} is unnecessary", node_name)).emit()
+                lint.build(&format!("braces around {} is unnecessary", node_name)).emit();
             });
         }
     }
@@ -1170,7 +1170,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedAllocation {
                             "unnecessary allocation, use `&mut` instead"
                         }
                     };
-                    lint.build(msg).emit()
+                    lint.build(msg).emit();
                 });
             }
         }