Auto merge of rust-lang#127174 - matthiaskrgr:rollup-q87j6cn, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#126018 (Remove the `box_pointers` lint.)
 - rust-lang#126895 (Fix simd_gather documentation)
 - rust-lang#126981 (Replace some magic booleans in match-lowering with enums)
 - rust-lang#127038 (Update test comment)
 - rust-lang#127053 (Update the LoongArch target documentation)
 - rust-lang#127069 (small correction to fmt::Pointer impl)
 - rust-lang#127157 (coverage: Avoid getting extra unexpansion info when we don't need it)
 - rust-lang#127160 (Add a regression test for rust-lang#123630)
 - rust-lang#127161 (Improve `run-make-support` library `args` API)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_lint/messages.ftl

@@ -56,8 +56,6 @@ lint_builtin_asm_labels = avoid using named labels in inline assembly
     .help = only local labels of the form `<number>:` should be used in inline asm
     .note = see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
-lint_builtin_box_pointers = type uses owned (Box type) pointers: {$ty}
-
 lint_builtin_clashing_extern_diff_name = `{$this}` redeclares `{$orig}` with a different signature
     .previous_decl_label = `{$orig}` previously declared here
     .mismatch_label = this signature doesn't match the previous declaration

compiler/rustc_lint/src/builtin.rs

@@ -24,9 +24,9 @@ use crate::fluent_generated as fluent;
 use crate::{
     errors::BuiltinEllipsisInclusiveRangePatterns,
     lints::{
-        BuiltinAnonymousParams, BuiltinBoxPointers, BuiltinConstNoMangle,
-        BuiltinDeprecatedAttrLink, BuiltinDeprecatedAttrLinkSuggestion, BuiltinDeprecatedAttrUsed,
-        BuiltinDerefNullptr, BuiltinEllipsisInclusiveRangePatternsLint, BuiltinExplicitOutlives,
+        BuiltinAnonymousParams, BuiltinConstNoMangle, BuiltinDeprecatedAttrLink,
+        BuiltinDeprecatedAttrLinkSuggestion, BuiltinDeprecatedAttrUsed, BuiltinDerefNullptr,
+        BuiltinEllipsisInclusiveRangePatternsLint, BuiltinExplicitOutlives,
         BuiltinExplicitOutlivesSuggestion, BuiltinFeatureIssueNote, BuiltinIncompleteFeatures,
         BuiltinIncompleteFeaturesHelp, BuiltinInternalFeatures, BuiltinKeywordIdents,
         BuiltinMissingCopyImpl, BuiltinMissingDebugImpl, BuiltinMissingDoc,
@@ -56,7 +56,6 @@ use rustc_middle::bug;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::GenericArgKind;
 use rustc_middle::ty::TypeVisitableExt;
 use rustc_middle::ty::Upcast;
 use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
@@ -134,80 +133,6 @@ impl EarlyLintPass for WhileTrue {
     }
 }
 
-declare_lint! {
-    /// The `box_pointers` lints use of the Box type.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,compile_fail
-    /// #![deny(box_pointers)]
-    /// struct Foo {
-    ///     x: Box<i32>,
-    /// }
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// This lint is mostly historical, and not particularly useful. `Box<T>`
-    /// used to be built into the language, and the only way to do heap
-    /// allocation. Today's Rust can call into other allocators, etc.
-    BOX_POINTERS,
-    Allow,
-    "use of owned (Box type) heap memory"
-}
-
-declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
-
-impl BoxPointers {
-    fn check_heap_type(&self, cx: &LateContext<'_>, span: Span, ty: Ty<'_>) {
-        for leaf in ty.walk() {
-            if let GenericArgKind::Type(leaf_ty) = leaf.unpack()
-                && leaf_ty.is_box()
-            {
-                cx.emit_span_lint(BOX_POINTERS, span, BuiltinBoxPointers { ty });
-            }
-        }
-    }
-}
-
-impl<'tcx> LateLintPass<'tcx> for BoxPointers {
-    fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
-        match it.kind {
-            hir::ItemKind::Fn(..)
-            | hir::ItemKind::TyAlias(..)
-            | hir::ItemKind::Enum(..)
-            | hir::ItemKind::Struct(..)
-            | hir::ItemKind::Union(..) => self.check_heap_type(
-                cx,
-                it.span,
-                cx.tcx.type_of(it.owner_id).instantiate_identity(),
-            ),
-            _ => (),
-        }
-
-        // If it's a struct, we also have to check the fields' types
-        match it.kind {
-            hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
-                for field in struct_def.fields() {
-                    self.check_heap_type(
-                        cx,
-                        field.span,
-                        cx.tcx.type_of(field.def_id).instantiate_identity(),
-                    );
-                }
-            }
-            _ => (),
-        }
-    }
-
-    fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
-        let ty = cx.typeck_results().node_type(e.hir_id);
-        self.check_heap_type(cx, e.span, ty);
-    }
-}
-
 declare_lint! {
     /// The `non_shorthand_field_patterns` lint detects using `Struct { x: x }`
     /// instead of `Struct { x }` in a pattern.
@@ -1640,7 +1565,6 @@ declare_lint_pass!(
     /// which are used by other parts of the compiler.
     SoftLints => [
         WHILE_TRUE,
-        BOX_POINTERS,
         NON_SHORTHAND_FIELD_PATTERNS,
         UNSAFE_CODE,
         MISSING_DOCS,

compiler/rustc_lint/src/lib.rs

@@ -187,7 +187,6 @@ late_lint_methods!(
             ImproperCTypesDefinitions: ImproperCTypesDefinitions,
             InvalidFromUtf8: InvalidFromUtf8,
             VariantSizeDifferences: VariantSizeDifferences,
-            BoxPointers: BoxPointers,
             PathStatements: PathStatements,
             LetUnderscore: LetUnderscore,
             InvalidReferenceCasting: InvalidReferenceCasting,
@@ -551,6 +550,10 @@ fn register_builtins(store: &mut LintStore) {
         "converted into hard error, see RFC #3535 \
          <https://rust-lang.github.io/rfcs/3535-constants-in-patterns.html> for more information",
     );
+    store.register_removed(
+        "box_pointers",
+        "it does not detect other kinds of allocations, and existed only for historical reasons",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {

compiler/rustc_lint/src/lints.rs

@@ -66,12 +66,6 @@ pub struct BuiltinWhileTrue {
     pub replace: String,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(lint_builtin_box_pointers)]
-pub struct BuiltinBoxPointers<'a> {
-    pub ty: Ty<'a>,
-}
-
 #[derive(LintDiagnostic)]
 #[diag(lint_builtin_non_shorthand_field_patterns)]
 pub struct BuiltinNonShorthandFieldPatterns {

compiler/rustc_mir_build/src/build/block.rs

@@ -1,3 +1,4 @@
+use crate::build::matches::{DeclareLetBindings, EmitStorageLive, ScheduleDrops};
 use crate::build::ForGuard::OutsideGuard;
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
 use rustc_middle::middle::region::Scope;
@@ -201,7 +202,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             pattern,
                             UserTypeProjections::none(),
                             &mut |this, _, _, node, span, _, _| {
-                                this.storage_live_binding(block, node, span, OutsideGuard, true);
+                                this.storage_live_binding(
+                                    block,
+                                    node,
+                                    span,
+                                    OutsideGuard,
+                                    ScheduleDrops::Yes,
+                                );
                             },
                         );
                         let else_block_span = this.thir[*else_block].span;
@@ -213,8 +220,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                     pattern,
                                     None,
                                     initializer_span,
-                                    false,
-                                    true,
+                                    DeclareLetBindings::No,
+                                    EmitStorageLive::No,
                                 )
                             });
                         matching.and(failure)
@@ -291,7 +298,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             pattern,
                             UserTypeProjections::none(),
                             &mut |this, _, _, node, span, _, _| {
-                                this.storage_live_binding(block, node, span, OutsideGuard, true);
+                                this.storage_live_binding(
+                                    block,
+                                    node,
+                                    span,
+                                    OutsideGuard,
+                                    ScheduleDrops::Yes,
+                                );
                                 this.schedule_drop_for_binding(node, span, OutsideGuard);
                             },
                         )

compiler/rustc_mir_build/src/build/expr/into.rs

@@ -1,6 +1,7 @@
 //! See docs in build/expr/mod.rs
 
 use crate::build::expr::category::{Category, RvalueFunc};
+use crate::build::matches::DeclareLetBindings;
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder, NeedsTemporary};
 use rustc_ast::InlineAsmOptions;
 use rustc_data_structures::fx::FxHashMap;
@@ -86,7 +87,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                     cond,
                                     Some(condition_scope), // Temp scope
                                     source_info,
-                                    true, // Declare `let` bindings normally
+                                    DeclareLetBindings::Yes, // Declare `let` bindings normally
                                 ));
 
                                 // Lower the `then` arm into its block.
@@ -163,7 +164,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             source_info,
                             // This flag controls how inner `let` expressions are lowered,
                             // but either way there shouldn't be any of those in here.
-                            true,
+                            DeclareLetBindings::LetNotPermitted,
                         )
                     });
                 let (short_circuit, continuation, constant) = match op {