Generate lint diagnostic message from BuiltinLintDiag

Translation of the lint message happens when the actual diagnostic is
created, not when the lint is buffered. Generating the message from
BuiltinLintDiag ensures that all required data to construct the message
is preserved in the LintBuffer, eventually allowing the messages to be
moved to fluent.

Remove the `msg` field from BufferedEarlyLint, it is either generated
from the data in the BuiltinLintDiag or stored inside
BuiltinLintDiag::Normal.

Author: Xiretza

compiler/rustc_ast_passes/messages.ftl

@@ -55,9 +55,6 @@ ast_passes_const_without_body =
 ast_passes_constraint_on_negative_bound =
     associated type constraints not allowed on negative bounds
 
-ast_passes_deprecated_where_clause_location =
-    where clause not allowed here
-
 ast_passes_equality_in_where = equality constraints are not yet supported in `where` clauses
     .label = not supported
     .suggestion = if `{$ident}` is an associated type you're trying to set, use the associated type binding syntax
@@ -80,8 +77,6 @@ ast_passes_extern_types_cannot = `type`s inside `extern` blocks cannot have {$de
     .suggestion = remove the {$remove_descr}
     .label = `extern` block begins here
 
-ast_passes_extern_without_abi = extern declarations without an explicit ABI are deprecated
-
 ast_passes_feature_on_non_nightly = `#![feature]` may not be used on the {$channel} release channel
     .suggestion = remove the attribute
     .stable_since = the feature `{$name}` has been stable since `{$since}` and no longer requires an attribute to enable

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -27,7 +27,6 @@ use std::ops::{Deref, DerefMut};
 use thin_vec::thin_vec;
 
 use crate::errors;
-use crate::fluent_generated as fluent;
 
 /// Is `self` allowed semantically as the first parameter in an `FnDecl`?
 enum SelfSemantic {
@@ -771,7 +770,6 @@ impl<'a> AstValidator<'a> {
                 MISSING_ABI,
                 id,
                 span,
-                fluent::ast_passes_extern_without_abi,
                 BuiltinLintDiag::MissingAbi(span, abi::Abi::FALLBACK),
             )
         }
@@ -1429,16 +1427,13 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             Self::check_decl_no_pat(&sig.decl, |span, ident, mut_ident| {
                 if mut_ident && matches!(ctxt, FnCtxt::Assoc(_)) {
                     if let Some(ident) = ident {
-                        let msg = match ctxt {
-                            FnCtxt::Foreign => fluent::ast_passes_pattern_in_foreign,
-                            _ => fluent::ast_passes_pattern_in_bodiless,
-                        };
-                        let diag = BuiltinLintDiag::PatternsInFnsWithoutBody(span, ident);
+                        let is_foreign = matches!(ctxt, FnCtxt::Foreign);
+                        let diag =
+                            BuiltinLintDiag::PatternsInFnsWithoutBody { span, ident, is_foreign };
                         self.lint_buffer.buffer_lint_with_diagnostic(
                             PATTERNS_IN_FNS_WITHOUT_BODY,
                             id,
                             span,
-                            msg,
                             diag,
                         )
                     }
@@ -1515,7 +1510,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 DEPRECATED_WHERE_CLAUSE_LOCATION,
                 item.id,
                 err.span,
-                fluent::ast_passes_deprecated_where_clause_location,
                 BuiltinLintDiag::DeprecatedWhereclauseLocation(sugg),
             );
         }

compiler/rustc_ast_passes/src/errors.rs

@@ -669,6 +669,7 @@ pub struct ConstAndCVariadic {
 
 #[derive(Diagnostic)]
 #[diag(ast_passes_pattern_in_foreign, code = E0130)]
+// FIXME: deduplicate with rustc_lint (`BuiltinLintDiag::PatternsInFnsWithoutBody`)
 pub struct PatternInForeign {
     #[primary_span]
     #[label]
@@ -677,6 +678,7 @@ pub struct PatternInForeign {
 
 #[derive(Diagnostic)]
 #[diag(ast_passes_pattern_in_bodiless, code = E0642)]
+// FIXME: deduplicate with rustc_lint (`BuiltinLintDiag::PatternsInFnsWithoutBody`)
 pub struct PatternInBodiless {
     #[primary_span]
     #[label]

compiler/rustc_attr/src/builtin.rs

@@ -532,11 +532,6 @@ pub fn cfg_matches(
                     UNEXPECTED_CFGS,
                     cfg.span,
                     lint_node_id,
-                    if let Some(value) = cfg.value {
-                        format!("unexpected `cfg` condition value: `{value}`")
-                    } else {
-                        format!("unexpected `cfg` condition value: (none)")
-                    },
                     BuiltinLintDiag::UnexpectedCfgValue(
                         (cfg.name, cfg.name_span),
                         cfg.value.map(|v| (v, cfg.value_span.unwrap())),
@@ -548,7 +543,6 @@ pub fn cfg_matches(
                     UNEXPECTED_CFGS,
                     cfg.span,
                     lint_node_id,
-                    format!("unexpected `cfg` condition name: `{}`", cfg.name),
                     BuiltinLintDiag::UnexpectedCfgName(
                         (cfg.name, cfg.name_span),
                         cfg.value.map(|v| (v, cfg.value_span.unwrap())),

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -1625,10 +1625,9 @@ impl<'a> TraitDef<'a> {
                                 BYTE_SLICE_IN_PACKED_STRUCT_WITH_DERIVE,
                                 sp,
                                 ast::CRATE_NODE_ID,
-                                format!(
-                                    "{ty} slice in a packed struct that derives a built-in trait"
-                                ),
-                                rustc_lint_defs::BuiltinLintDiag::ByteSliceInPackedStructWithDerive,
+                                rustc_lint_defs::BuiltinLintDiag::ByteSliceInPackedStructWithDerive {
+                                    ty: ty.to_string(),
+                                },
                             );
                         } else {
                             // Wrap the expression in `{...}`, causing a copy.

compiler/rustc_builtin_macros/src/format.rs

@@ -557,7 +557,6 @@ fn make_format_args(
             let arg_name = args.explicit_args()[index].kind.ident().unwrap();
             ecx.buffered_early_lint.push(BufferedEarlyLint {
                 span: arg_name.span.into(),
-                msg: format!("named argument `{}` is not used by name", arg_name.name).into(),
                 node_id: rustc_ast::CRATE_NODE_ID,
                 lint_id: LintId::of(NAMED_ARGUMENTS_USED_POSITIONALLY),
                 diagnostic: BuiltinLintDiag::NamedArgumentUsedPositionally {

compiler/rustc_expand/src/base.rs

@@ -1382,7 +1382,6 @@ fn pretty_printing_compatibility_hack(item: &Item, sess: &Session) -> bool {
                                         PROC_MACRO_BACK_COMPAT,
                                         item.ident.span,
                                         ast::CRATE_NODE_ID,
-                                        "using an old version of `rental`",
                                         BuiltinLintDiag::ProcMacroBackCompat(
                                         "older versions of the `rental` crate will stop compiling in future versions of Rust; \
                                         please update to `rental` v0.5.6, or switch to one of the `rental` alternatives".to_string()

compiler/rustc_expand/src/expand.rs

@@ -1721,7 +1721,6 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                     UNUSED_DOC_COMMENTS,
                     current_span,
                     self.cx.current_expansion.lint_node_id,
-                    "unused doc comment",
                     BuiltinLintDiag::UnusedDocComment(attr.span),
                 );
             } else if rustc_attr::is_builtin_attr(attr) {
@@ -1733,7 +1732,6 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                         UNUSED_ATTRIBUTES,
                         attr.span,
                         self.cx.current_expansion.lint_node_id,
-                        format!("unused attribute `{attr_name}`"),
                         BuiltinLintDiag::UnusedBuiltinAttribute {
                             attr_name,
                             macro_name: pprust::path_to_string(&call.path),

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -82,7 +82,6 @@ impl<'a> ParserAnyMacro<'a> {
                     SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
                     parser.token.span,
                     lint_node_id,
-                    "trailing semicolon in macro used in expression position",
                     BuiltinLintDiag::TrailingMacro(is_trailing_mac, macro_ident),
                 );
             }
@@ -1153,7 +1152,6 @@ fn check_matcher_core<'tt>(
                             RUST_2021_INCOMPATIBLE_OR_PATTERNS,
                             span,
                             ast::CRATE_NODE_ID,
-                            "the meaning of the `pat` fragment specifier is changing in Rust 2021, which may affect this macro",
                             BuiltinLintDiag::OrPatternsBackCompat(span, suggestion),
                         );
                     }

compiler/rustc_interface/src/util.rs

@@ -388,7 +388,6 @@ pub(crate) fn check_attr_crate_type(
                             lint::builtin::UNKNOWN_CRATE_TYPES,
                             ast::CRATE_NODE_ID,
                             span,
-                            "invalid `crate_type` value",
                             BuiltinLintDiag::UnknownCrateTypes(
                                 span,
                                 "did you mean".to_string(),

compiler/rustc_lint/messages.ftl

@@ -187,6 +187,9 @@ lint_deprecated_lint_name =
     .suggestion = change it to
     .help = change it to {$replace}
 
+lint_deprecated_where_clause_location =
+    where clause not allowed here
+
 lint_diag_out_of_impl =
     diagnostics should only be created in `Diagnostic`/`Subdiagnostic`/`LintDiagnostic` impls
 
@@ -216,6 +219,8 @@ lint_expectation = this lint expectation is unfulfilled
     .note = the `unfulfilled_lint_expectations` lint can't be expected and will always produce this message
     .rationale = {$rationale}
 
+lint_extern_without_abi = extern declarations without an explicit ABI are deprecated
+
 lint_for_loops_over_fallibles =
     for loop over {$article} `{$ty}`. This is more readably written as an `if let` statement
     .suggestion = consider using `if let` to clear intent
@@ -515,6 +520,12 @@ lint_path_statement_drop = path statement drops value
 
 lint_path_statement_no_effect = path statement with no effect
 
+lint_pattern_in_bodiless = patterns aren't allowed in functions without bodies
+    .label = pattern not allowed in function without body
+
+lint_pattern_in_foreign = patterns aren't allowed in foreign function declarations
+    .label = pattern not allowed in foreign function
+
 lint_ptr_null_checks_fn_ptr = function pointers are not nullable, so checking them for null will always return false
     .help = wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
     .label = expression has type `{$orig_ty}`

compiler/rustc_lint/src/context.rs

@@ -536,12 +536,11 @@ pub trait LintContext {
         &self,
         lint: &'static Lint,
         span: Option<impl Into<MultiSpan>>,
-        msg: impl Into<DiagMessage>,
         decorate: impl for<'a, 'b> FnOnce(&'b mut Diag<'a, ()>),
         diagnostic: BuiltinLintDiag,
     ) {
         // We first generate a blank diagnostic.
-        self.opt_span_lint(lint, span, msg, |db| {
+        self.opt_span_lint(lint, span, diagnostics::builtin_message(&diagnostic), |db| {
             // Now, set up surrounding context.
             diagnostics::builtin(self.sess(), diagnostic, db);
             // Rewrap `db`, and pass control to the user.