remove mutability of fn args that don't need it

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1391,7 +1391,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 /// When encountering an equality constraint in a `where` clause, emit an error. If the code seems
 /// like it's setting an associated type, provide an appropriate suggestion.
 fn deny_equality_constraints(
-    this: &mut AstValidator<'_>,
+    this: &AstValidator<'_>,
     predicate: &WhereEqPredicate,
     generics: &Generics,
 ) {

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -3203,7 +3203,7 @@ enum AnnotatedBorrowFnSignature<'tcx> {
 impl<'tcx> AnnotatedBorrowFnSignature<'tcx> {
     /// Annotate the provided diagnostic with information about borrow from the fn signature that
     /// helps explain.
-    pub(crate) fn emit(&self, cx: &mut MirBorrowckCtxt<'_, 'tcx>, diag: &mut Diagnostic) -> String {
+    pub(crate) fn emit(&self, cx: &MirBorrowckCtxt<'_, 'tcx>, diag: &mut Diagnostic) -> String {
         match self {
             &AnnotatedBorrowFnSignature::Closure { argument_ty, argument_span } => {
                 diag.span_label(

compiler/rustc_borrowck/src/type_check/liveness/polonius.rs

@@ -87,7 +87,7 @@ pub(super) fn populate_access_facts<'a, 'tcx>(
     body: &Body<'tcx>,
     location_table: &LocationTable,
     move_data: &MoveData<'tcx>,
-    dropped_at: &mut Vec<(Local, Location)>,
+    dropped_at: &Vec<(Local, Location)>,
 ) {
     debug!("populate_access_facts()");
 

compiler/rustc_borrowck/src/type_check/liveness/trace.rs

@@ -567,10 +567,7 @@ impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
         });
     }
 
-    fn compute_drop_data(
-        typeck: &mut TypeChecker<'_, 'tcx>,
-        dropped_ty: Ty<'tcx>,
-    ) -> DropData<'tcx> {
+    fn compute_drop_data(typeck: &TypeChecker<'_, 'tcx>, dropped_ty: Ty<'tcx>) -> DropData<'tcx> {
         debug!("compute_drop_data(dropped_ty={:?})", dropped_ty,);
 
         match typeck

compiler/rustc_builtin_macros/src/asm.rs

@@ -29,7 +29,7 @@ pub struct AsmArgs {
 }
 
 fn parse_args<'a>(
-    ecx: &mut ExtCtxt<'a>,
+    ecx: &ExtCtxt<'a>,
     sp: Span,
     tts: TokenStream,
     is_global_asm: bool,
@@ -295,7 +295,7 @@ pub fn parse_asm_args<'a>(
 ///
 /// This function must be called immediately after the option token is parsed.
 /// Otherwise, the suggestion will be incorrect.
-fn err_duplicate_option(p: &mut Parser<'_>, symbol: Symbol, span: Span) {
+fn err_duplicate_option(p: &Parser<'_>, symbol: Symbol, span: Span) {
     // Tool-only output
     let full_span = if p.token.kind == token::Comma { span.to(p.token.span) } else { span };
     p.sess.span_diagnostic.emit_err(errors::AsmOptAlreadyprovided { span, symbol, full_span });
@@ -307,7 +307,7 @@ fn err_duplicate_option(p: &mut Parser<'_>, symbol: Symbol, span: Span) {
 /// This function must be called immediately after the option token is parsed.
 /// Otherwise, the error will not point to the correct spot.
 fn try_set_option<'a>(
-    p: &mut Parser<'a>,
+    p: &Parser<'a>,
     args: &mut AsmArgs,
     symbol: Symbol,
     option: ast::InlineAsmOptions,

compiler/rustc_builtin_macros/src/assert.rs

@@ -111,7 +111,7 @@ fn expr_if_not(
     cx.expr_if(span, cx.expr(span, ExprKind::Unary(UnOp::Not, cond)), then, els)
 }
 
-fn parse_assert<'a>(cx: &mut ExtCtxt<'a>, sp: Span, stream: TokenStream) -> PResult<'a, Assert> {
+fn parse_assert<'a>(cx: &ExtCtxt<'a>, sp: Span, stream: TokenStream) -> PResult<'a, Assert> {
     let mut parser = cx.new_parser_from_tts(stream);
 
     if parser.token == token::Eof {

compiler/rustc_builtin_macros/src/cfg.rs

@@ -35,7 +35,7 @@ pub fn expand_cfg(
     }
 }
 
-fn parse_cfg<'a>(cx: &mut ExtCtxt<'a>, span: Span, tts: TokenStream) -> PResult<'a, ast::MetaItem> {
+fn parse_cfg<'a>(cx: &ExtCtxt<'a>, span: Span, tts: TokenStream) -> PResult<'a, ast::MetaItem> {
     let mut p = cx.new_parser_from_tts(tts);
 
     if p.token == token::Eof {

compiler/rustc_builtin_macros/src/cfg_accessible.rs

@@ -10,7 +10,7 @@ use rustc_span::Span;
 
 pub(crate) struct Expander;
 
-fn validate_input<'a>(ecx: &mut ExtCtxt<'_>, mi: &'a ast::MetaItem) -> Option<&'a ast::Path> {
+fn validate_input<'a>(ecx: &ExtCtxt<'_>, mi: &'a ast::MetaItem) -> Option<&'a ast::Path> {
     use errors::CfgAccessibleInvalid::*;
     match mi.meta_item_list() {
         None => {}

compiler/rustc_builtin_macros/src/concat_bytes.rs

@@ -8,7 +8,7 @@ use crate::errors;
 
 /// Emits errors for literal expressions that are invalid inside and outside of an array.
 fn invalid_type_err(
-    cx: &mut base::ExtCtxt<'_>,
+    cx: &base::ExtCtxt<'_>,
     token_lit: ast::token::Lit,
     span: Span,
     is_nested: bool,
@@ -67,7 +67,7 @@ fn invalid_type_err(
 }
 
 fn handle_array_element(
-    cx: &mut base::ExtCtxt<'_>,
+    cx: &base::ExtCtxt<'_>,
     has_errors: &mut bool,
     missing_literals: &mut Vec<rustc_span::Span>,
     expr: &P<rustc_ast::Expr>,

compiler/rustc_builtin_macros/src/deriving/clone.rs

@@ -94,7 +94,7 @@ pub fn expand_deriving_clone(
 
 fn cs_clone_simple(
     name: &str,
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     trait_span: Span,
     substr: &Substructure<'_>,
     is_union: bool,

compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs

@@ -51,7 +51,7 @@ pub fn expand_deriving_eq(
 }
 
 fn cs_total_eq_assert(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     trait_span: Span,
     substr: &Substructure<'_>,
 ) -> BlockOrExpr {

compiler/rustc_builtin_macros/src/deriving/debug.rs

@@ -46,7 +46,7 @@ pub fn expand_deriving_debug(
     trait_def.expand(cx, mitem, item, push)
 }
 
-fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> BlockOrExpr {
+fn show_substructure(cx: &ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> BlockOrExpr {
     // We want to make sure we have the ctxt set so that we can use unstable methods
     let span = cx.with_def_site_ctxt(span);
 
@@ -210,7 +210,7 @@ fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>
 /// }
 /// ```
 fn show_fieldless_enum(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     span: Span,
     def: &EnumDef,
     substr: &Substructure<'_>,

compiler/rustc_builtin_macros/src/deriving/default.rs

@@ -52,7 +52,7 @@ pub fn expand_deriving_default(
 }
 
 fn default_struct_substructure(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     trait_span: Span,
     substr: &Substructure<'_>,
     summary: &StaticFields,
@@ -79,7 +79,7 @@ fn default_struct_substructure(
 }
 
 fn default_enum_substructure(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     trait_span: Span,
     enum_def: &EnumDef,
 ) -> BlockOrExpr {
@@ -98,7 +98,7 @@ fn default_enum_substructure(
 }
 
 fn extract_default_variant<'a>(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     enum_def: &'a EnumDef,
     trait_span: Span,
 ) -> Result<&'a rustc_ast::Variant, ()> {
@@ -169,7 +169,7 @@ fn extract_default_variant<'a>(
 }
 
 fn validate_default_attribute(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     default_variant: &rustc_ast::Variant,
 ) -> Result<(), ()> {
     let attrs: SmallVec<[_; 1]> =

compiler/rustc_builtin_macros/src/deriving/encodable.rs

@@ -147,7 +147,7 @@ pub fn expand_deriving_rustc_encodable(
 }
 
 fn encodable_substructure(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     trait_span: Span,
     substr: &Substructure<'_>,
     krate: Symbol,

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

@@ -552,7 +552,7 @@ impl<'a> TraitDef<'a> {
     /// therefore does not get bound by the derived trait.
     fn create_derived_impl(
         &self,
-        cx: &mut ExtCtxt<'_>,
+        cx: &ExtCtxt<'_>,
         type_ident: Ident,
         generics: &Generics,
         field_tys: Vec<P<ast::Ty>>,
@@ -910,7 +910,7 @@ impl<'a> MethodDef<'a> {
 
     fn get_ret_ty(
         &self,
-        cx: &mut ExtCtxt<'_>,
+        cx: &ExtCtxt<'_>,
         trait_: &TraitDef<'_>,
         generics: &Generics,
         type_ident: Ident,
@@ -931,7 +931,7 @@ impl<'a> MethodDef<'a> {
     //   `&self`.
     fn extract_arg_details(
         &self,
-        cx: &mut ExtCtxt<'_>,
+        cx: &ExtCtxt<'_>,
         trait_: &TraitDef<'_>,
         type_ident: Ident,
         generics: &Generics,
@@ -967,7 +967,7 @@ impl<'a> MethodDef<'a> {
 
     fn create_method(
         &self,
-        cx: &mut ExtCtxt<'_>,
+        cx: &ExtCtxt<'_>,
         trait_: &TraitDef<'_>,
         type_ident: Ident,
         generics: &Generics,
@@ -1406,7 +1406,7 @@ impl<'a> MethodDef<'a> {
 
 // general helper methods.
 impl<'a> TraitDef<'a> {
-    fn summarise_struct(&self, cx: &mut ExtCtxt<'_>, struct_def: &VariantData) -> StaticFields {
+    fn summarise_struct(&self, cx: &ExtCtxt<'_>, struct_def: &VariantData) -> StaticFields {
         let mut named_idents = Vec::new();
         let mut just_spans = Vec::new();
         for field in struct_def.fields() {
@@ -1433,7 +1433,7 @@ impl<'a> TraitDef<'a> {
 
     fn create_struct_patterns(
         &self,
-        cx: &mut ExtCtxt<'_>,
+        cx: &ExtCtxt<'_>,
         struct_path: ast::Path,
         struct_def: &'a VariantData,
         prefixes: &[String],
@@ -1526,7 +1526,7 @@ impl<'a> TraitDef<'a> {
 
     fn create_struct_pattern_fields(
         &self,
-        cx: &mut ExtCtxt<'_>,
+        cx: &ExtCtxt<'_>,
         struct_def: &'a VariantData,
         prefixes: &[String],
     ) -> Vec<FieldInfo> {
@@ -1543,7 +1543,7 @@ impl<'a> TraitDef<'a> {
 
     fn create_struct_field_access_fields(
         &self,
-        cx: &mut ExtCtxt<'_>,
+        cx: &ExtCtxt<'_>,
         selflike_args: &[P<Expr>],
         struct_def: &'a VariantData,
         is_packed: bool,

compiler/rustc_builtin_macros/src/deriving/hash.rs

@@ -46,11 +46,7 @@ pub fn expand_deriving_hash(
     hash_trait_def.expand(cx, mitem, item, push);
 }
 
-fn hash_substructure(
-    cx: &mut ExtCtxt<'_>,
-    trait_span: Span,
-    substr: &Substructure<'_>,
-) -> BlockOrExpr {
+fn hash_substructure(cx: &ExtCtxt<'_>, trait_span: Span, substr: &Substructure<'_>) -> BlockOrExpr {
     let [state_expr] = substr.nonselflike_args else {
         cx.span_bug(trait_span, "incorrect number of arguments in `derive(Hash)`");
     };

compiler/rustc_builtin_macros/src/deriving/mod.rs

@@ -120,7 +120,7 @@ fn call_unreachable(cx: &ExtCtxt<'_>, span: Span) -> P<ast::Expr> {
 // does *not* add `where T: Structural` for parameters `T` in `...`.
 // (That's the main reason we cannot use TraitDef here.)
 fn inject_impl_of_structural_trait(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     span: Span,
     item: &Annotatable,
     structural_path: generic::ty::Path,
@@ -211,7 +211,7 @@ fn inject_impl_of_structural_trait(
 }
 
 fn assert_ty_bounds(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     stmts: &mut ThinVec<ast::Stmt>,
     ty: P<ast::Ty>,
     span: Span,

compiler/rustc_builtin_macros/src/edition_panic.rs

@@ -40,7 +40,7 @@ pub fn expand_unreachable<'cx>(
 
 fn expand<'cx>(
     mac: rustc_span::Symbol,
-    cx: &'cx mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     sp: Span,
     tts: TokenStream,
 ) -> Box<dyn MacResult + 'cx> {

compiler/rustc_builtin_macros/src/format.rs

@@ -62,7 +62,7 @@ struct MacroInput {
 /// ```text
 /// Ok((fmtstr, parsed arguments))
 /// ```
-fn parse_args<'a>(ecx: &mut ExtCtxt<'a>, sp: Span, tts: TokenStream) -> PResult<'a, MacroInput> {
+fn parse_args<'a>(ecx: &ExtCtxt<'a>, sp: Span, tts: TokenStream) -> PResult<'a, MacroInput> {
     let mut args = FormatArguments::new();
 
     let mut p = ecx.new_parser_from_tts(tts);
@@ -562,7 +562,7 @@ fn invalid_placeholder_type_error(
 }
 
 fn report_missing_placeholders(
-    ecx: &mut ExtCtxt<'_>,
+    ecx: &ExtCtxt<'_>,
     unused: Vec<(Span, bool)>,
     detect_foreign_fmt: bool,
     str_style: Option<usize>,
@@ -674,7 +674,7 @@ fn report_missing_placeholders(
 /// there are named arguments or numbered positional arguments in the
 /// format string.
 fn report_invalid_references(
-    ecx: &mut ExtCtxt<'_>,
+    ecx: &ExtCtxt<'_>,
     invalid_refs: &[(usize, Option<Span>, PositionUsedAs, FormatArgPositionKind)],
     template: &[FormatArgsPiece],
     fmt_span: Span,

compiler/rustc_builtin_macros/src/test.rs

@@ -93,7 +93,7 @@ pub fn expand_bench(
 }
 
 pub fn expand_test_or_bench(
-    cx: &mut ExtCtxt<'_>,
+    cx: &ExtCtxt<'_>,
     attr_sp: Span,
     item: Annotatable,
     is_bench: bool,

compiler/rustc_builtin_macros/src/type_ascribe.rs

@@ -23,7 +23,7 @@ pub fn expand_type_ascribe(
     return MacEager::expr(asc_expr);
 }
 
-fn parse_ascribe<'a>(cx: &mut ExtCtxt<'a>, stream: TokenStream) -> PResult<'a, (P<Expr>, P<Ty>)> {
+fn parse_ascribe<'a>(cx: &ExtCtxt<'a>, stream: TokenStream) -> PResult<'a, (P<Expr>, P<Ty>)> {
     let mut parser = cx.new_parser_from_tts(stream);
 
     let expr = parser.parse_expr()?;

compiler/rustc_codegen_llvm/src/allocator.rs

@@ -14,7 +14,7 @@ use crate::ModuleLlvm;
 
 pub(crate) unsafe fn codegen(
     tcx: TyCtxt<'_>,
-    module_llvm: &mut ModuleLlvm,
+    module_llvm: &ModuleLlvm,
     module_name: &str,
     kind: AllocatorKind,
     alloc_error_handler_kind: AllocatorKind,

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -580,7 +580,7 @@ fn thin_lto(
 pub(crate) fn run_pass_manager(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     diag_handler: &Handler,
-    module: &mut ModuleCodegen<ModuleLlvm>,
+    module: &ModuleCodegen<ModuleLlvm>,
     thin: bool,
 ) -> Result<(), FatalError> {
     let _timer = cgcx.prof.verbose_generic_activity_with_arg("LLVM_lto_optimize", &*module.name);

compiler/rustc_codegen_ssa/src/back/rpath.rs

@@ -13,7 +13,7 @@ pub struct RPathConfig<'a> {
     pub linker_is_gnu: bool,
 }
 
-pub fn get_rpath_flags(config: &mut RPathConfig<'_>) -> Vec<OsString> {
+pub fn get_rpath_flags(config: &RPathConfig<'_>) -> Vec<OsString> {
     // No rpath on windows
     if !config.has_rpath {
         return Vec::new();
@@ -53,7 +53,7 @@ fn rpaths_to_flags(rpaths: Vec<OsString>) -> Vec<OsString> {
     ret
 }
 
-fn get_rpaths(config: &mut RPathConfig<'_>) -> Vec<OsString> {
+fn get_rpaths(config: &RPathConfig<'_>) -> Vec<OsString> {
     debug!("output: {:?}", config.out_filename.display());
     debug!("libs:");
     for libpath in config.libs {
@@ -74,11 +74,11 @@ fn get_rpaths(config: &mut RPathConfig<'_>) -> Vec<OsString> {
     minimize_rpaths(&rpaths)
 }
 
-fn get_rpaths_relative_to_output(config: &mut RPathConfig<'_>) -> Vec<OsString> {
+fn get_rpaths_relative_to_output(config: &RPathConfig<'_>) -> Vec<OsString> {
     config.libs.iter().map(|a| get_rpath_relative_to_output(config, a)).collect()
 }
 
-fn get_rpath_relative_to_output(config: &mut RPathConfig<'_>, lib: &Path) -> OsString {
+fn get_rpath_relative_to_output(config: &RPathConfig<'_>, lib: &Path) -> OsString {
     // Mac doesn't appear to support $ORIGIN
     let prefix = if config.is_like_osx { "@loader_path" } else { "$ORIGIN" };