Remove LangItems::require

It's just a short wrapper used by `tcx.require_lang_item`. Deleting it
gives us a negative diff.

compiler/rustc_codegen_cranelift/src/base.rs

@@ -966,11 +966,7 @@ fn codegen_panic_inner<'tcx>(
     args: &[Value],
     span: Span,
 ) {
-    let def_id = fx
-        .tcx
-        .lang_items()
-        .require(lang_item)
-        .unwrap_or_else(|e| fx.tcx.sess.span_fatal(span, e.to_string()));
+    let def_id = fx.tcx.require_lang_item(lang_item, Some(span));
 
     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
     let symbol_name = fx.tcx.symbol_name(instance).name;

compiler/rustc_hir/src/lang_items.rs

@@ -8,7 +8,6 @@
 //! * Functions called by the compiler itself.
 
 use crate::def_id::DefId;
-use crate::errors::LangItemError;
 use crate::{MethodKind, Target};
 
 use rustc_ast as ast;
@@ -42,13 +41,6 @@ impl LanguageItems {
         self.items[item as usize] = Some(def_id);
     }
 
-    /// Requires that a given `LangItem` was bound and returns the corresponding `DefId`.
-    /// If it wasn't bound, e.g. due to a missing `#[lang = "<it.name()>"]`,
-    /// returns an error encapsulating the `LangItem`.
-    pub fn require(&self, it: LangItem) -> Result<DefId, LangItemError> {
-        self.get(it).ok_or_else(|| LangItemError(it))
-    }
-
     pub fn iter(&self) -> impl Iterator<Item = (LangItem, DefId)> + '_ {
         self.items
             .iter()

compiler/rustc_hir/src/lib.rs

@@ -30,7 +30,6 @@ pub mod def;
 pub mod def_path_hash_map;
 pub mod definitions;
 pub mod diagnostic_items;
-pub mod errors;
 pub use rustc_span::def_id;
 mod hir;
 pub mod hir_id;

compiler/rustc_hir_analysis/src/coherence/builtin.rs

@@ -298,9 +298,7 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
 
     let coerce_unsized_trait = tcx.require_lang_item(LangItem::CoerceUnsized, Some(span));
 
-    let unsize_trait = tcx.lang_items().require(LangItem::Unsize).unwrap_or_else(|err| {
-        tcx.sess.fatal(format!("`CoerceUnsized` implementation {}", err.to_string()));
-    });
+    let unsize_trait = tcx.require_lang_item(LangItem::Unsize, Some(span));
 
     let source = tcx.type_of(impl_did).subst_identity();
     let trait_ref = tcx.impl_trait_ref(impl_did).unwrap().subst_identity();

compiler/rustc_middle/messages.ftl

@@ -39,5 +39,7 @@ middle_strict_coherence_needs_negative_coherence =
     to use `strict_coherence` on this trait, the `with_negative_coherence` feature must be enabled
     .label = due to this attribute
 
+middle_requires_lang_item = requires `{$name}` lang_item
+
 middle_const_not_used_in_type_alias =
     const parameter `{$ct}` is part of concrete type but not used in parameter list for the `impl Trait` type alias

compiler/rustc_middle/src/error.rs

@@ -1,5 +1,5 @@
 use rustc_macros::Diagnostic;
-use rustc_span::Span;
+use rustc_span::{Span, Symbol};
 
 use crate::ty::Ty;
 
@@ -73,6 +73,14 @@ pub(crate) struct StrictCoherenceNeedsNegativeCoherence {
     pub attr_span: Option<Span>,
 }
 
+#[derive(Diagnostic)]
+#[diag(middle_requires_lang_item)]
+pub(crate) struct RequiresLangItem {
+    #[primary_span]
+    pub span: Option<Span>,
+    pub name: Symbol,
+}
+
 #[derive(Diagnostic)]
 #[diag(middle_const_not_used_in_type_alias)]
 pub(super) struct ConstNotUsedTraitAlias {

compiler/rustc_middle/src/middle/lang_items.rs

@@ -18,12 +18,8 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Returns the `DefId` for a given `LangItem`.
     /// If not found, fatally aborts compilation.
     pub fn require_lang_item(self, lang_item: LangItem, span: Option<Span>) -> DefId {
-        self.lang_items().require(lang_item).unwrap_or_else(|err| {
-            if let Some(span) = span {
-                self.sess.span_fatal(span, err.to_string())
-            } else {
-                self.sess.fatal(err.to_string())
-            }
+        self.lang_items().get(lang_item).unwrap_or_else(|| {
+            self.sess.emit_fatal(crate::error::RequiresLangItem { span, name: lang_item.name() });
         })
     }
 

src/tools/clippy/clippy_lints/src/matches/redundant_pattern_match.rs

@@ -289,10 +289,11 @@ fn is_pat_variant(cx: &LateContext<'_>, pat: &Pat<'_>, path: &QPath<'_>, expecte
     let Some(id) = cx.typeck_results().qpath_res(path, pat.hir_id).opt_def_id() else { return false };
 
     match expected_item {
-        Item::Lang(expected_lang_item) => {
-            let expected_id = cx.tcx.lang_items().require(expected_lang_item).unwrap();
-            cx.tcx.parent(id) == expected_id
-        },
+        Item::Lang(expected_lang_item) => cx
+            .tcx
+            .lang_items()
+            .get(expected_lang_item)
+            .map_or(false, |expected_id| cx.tcx.parent(id) == expected_id),
         Item::Diag(expected_ty, expected_variant) => {
             let ty = cx.typeck_results().pat_ty(pat);