avoid string dispatch in fluent

compiler/rustc_error_messages/locales/en-US/passes.ftl

@@ -596,23 +596,25 @@ passes_unrecognized_repr_hint =
     unrecognized representation hint
     .help = valid reprs are `C`, `align`, `packed`, `transparent`, `simd`, `i8`, `u8`, `i16`, `u16`, `i32`, `u32`, `i64`, `u64`, `i128`, `u128`, `isize`, `usize`
 
-passes_attribute_should_be_applied_to =
+passes_attr_application_enum =
-    attribute should be applied to {$what ->
+    attribute should be applied to an enum
-        [enum] an enum
+    .label = not an enum
-        [struct] a struct
+
-        [struct-union] a struct or union
+passes_attr_application_struct =
-        [struct-enum-union] a struct, enum, or union
+    attribute should be applied to a struct
-        [struct-enum-function-union] a struct, enum, function, or union
+    .label = not a struct
-        *[unspecified] (unspecified--this is a compiler bug)
+
-    }
+passes_attr_application_struct_union =
-    .label = not {$what ->
+    attribute should be applied to a struct or union
-        [enum] an enum
+    .label = not a struct or union
-        [struct] a struct
+
-        [struct-union] a struct or union
+passes_attr_application_struct_enum_union =
-        [struct-enum-union] a struct, enum, or union
+    attribute should be applied to a struct, enum, or union
-        [struct-enum-function-union] a struct, enum, function, or union
+    .label = not a struct, enum, or union
-        *[unspecified] (unspecified--this is a compiler bug)
+
-    }
+passes_attr_application_struct_enum_function_union =
+    attribute should be applied to a struct, enum, function, or union
+    .label = not a struct, enum, function, or union
 
 passes_transparent_incompatible =
     transparent {$target} cannot have other repr hints

compiler/rustc_passes/src/check_attr.rs

@@ -5,8 +5,8 @@
 //! item.
 
 use crate::errors::{
-    self, AttributeShouldBeAppliedTo, DebugVisualizerUnreadable, InvalidAttrAtCrateLevel,
+    self, AttrApplication, DebugVisualizerUnreadable, InvalidAttrAtCrateLevel, ObjectLifetimeErr,
-    ObjectLifetimeErr, OnlyHasEffectOn, TransparentIncompatible, UnrecognizedReprHint,
+    OnlyHasEffectOn, TransparentIncompatible, UnrecognizedReprHint,
 };
 use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
 use rustc_data_structures::fx::FxHashMap;
@@ -1594,12 +1594,17 @@ fn check_repr(
                 continue;
             }
 
-            let what = match hint.name_or_empty() {
+            match hint.name_or_empty() {
                 sym::C => {
                     is_c = true;
                     match target {
                         Target::Struct | Target::Union | Target::Enum => continue,
-                        _ => "struct-enum-union",
+                        _ => {
+                            self.tcx.sess.emit_err(AttrApplication::StructEnumUnion {
+                                hint_span: hint.span(),
+                                span,
+                            });
+                        }
                     }
                 }
                 sym::align => {
@@ -1615,12 +1620,20 @@ fn check_repr(
 
                     match target {
                         Target::Struct | Target::Union | Target::Enum | Target::Fn => continue,
-                        _ => "struct-enum-function-union",
+                        _ => {
+                            self.tcx.sess.emit_err(AttrApplication::StructEnumFunctionUnion {
+                                hint_span: hint.span(),
+                                span,
+                            });
+                        }
                     }
                 }
                 sym::packed => {
                     if target != Target::Struct && target != Target::Union {
-                        "struct-union"
+                        self.tcx.sess.emit_err(AttrApplication::StructUnion {
+                            hint_span: hint.span(),
+                            span,
+                        });
                     } else {
                         continue;
                     }
@@ -1628,7 +1641,9 @@ fn check_repr(
                 sym::simd => {
                     is_simd = true;
                     if target != Target::Struct {
-                        "struct"
+                        self.tcx
+                            .sess
+                            .emit_err(AttrApplication::Struct { hint_span: hint.span(), span });
                     } else {
                         continue;
                     }
@@ -1637,7 +1652,12 @@ fn check_repr(
                     is_transparent = true;
                     match target {
                         Target::Struct | Target::Union | Target::Enum => continue,
-                        _ => "struct-enum-union",
+                        _ => {
+                            self.tcx.sess.emit_err(AttrApplication::StructEnumUnion {
+                                hint_span: hint.span(),
+                                span,
+                            });
+                        }
                     }
                 }
                 sym::i8
@@ -1654,7 +1674,9 @@ fn check_repr(
                 | sym::usize => {
                     int_reprs += 1;
                     if target != Target::Enum {
-                        "enum"
+                        self.tcx
+                            .sess
+                            .emit_err(AttrApplication::Enum { hint_span: hint.span(), span });
                     } else {
                         continue;
                     }
@@ -1664,12 +1686,6 @@ fn check_repr(
                     continue;
                 }
             };
-
-            self.tcx.sess.emit_err(AttributeShouldBeAppliedTo {
-                hint_span: hint.span(),
-                span,
-                what,
-            });
         }
 
         // Just point at all repr hints if there are any incompatibilities.

compiler/rustc_passes/src/errors.rs

@@ -1288,13 +1288,42 @@ pub struct UnrecognizedReprHint {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes::attribute_should_be_applied_to, code = "E0517")]
+pub enum AttrApplication {
-pub struct AttributeShouldBeAppliedTo<'a> {
+    #[diag(passes::attr_application_enum, code = "E0517")]
-    #[primary_span]
+    Enum {
-    pub hint_span: Span,
+        #[primary_span]
-    #[label]
+        hint_span: Span,
-    pub span: Span,
+        #[label]
-    pub what: &'a str,
+        span: Span,
+    },
+    #[diag(passes::attr_application_struct, code = "E0517")]
+    Struct {
+        #[primary_span]
+        hint_span: Span,
+        #[label]
+        span: Span,
+    },
+    #[diag(passes::attr_application_struct_union, code = "E0517")]
+    StructUnion {
+        #[primary_span]
+        hint_span: Span,
+        #[label]
+        span: Span,
+    },
+    #[diag(passes::attr_application_struct_enum_union, code = "E0517")]
+    StructEnumUnion {
+        #[primary_span]
+        hint_span: Span,
+        #[label]
+        span: Span,
+    },
+    #[diag(passes::attr_application_struct_enum_function_union, code = "E0517")]
+    StructEnumFunctionUnion {
+        #[primary_span]
+        hint_span: Span,
+        #[label]
+        span: Span,
+    },
 }
 
 #[derive(Diagnostic)]