Rollup merge of #149363 - scrabsha:rust/sasha/vkknqylzvzlu, r=jdonszelmann

Port the `#![windows_subsystem]` attribute to the new attribute system

Part of rust-lang/rust#131229.

I think it's worth running the Windows test suite before merging that (I don't have the rights for this).

compiler/rustc_attr_parsing/src/attributes/crate_level.rs

@@ -1,3 +1,5 @@
+use rustc_hir::attrs::WindowsSubsystemKind;
+
 use super::prelude::*;
 
 pub(crate) struct CrateNameParser;
@@ -142,3 +144,34 @@ impl<S: Stage> NoArgsAttributeParser<S> for RustcCoherenceIsCoreParser {
     const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::CrateLevel;
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::RustcCoherenceIsCore;
 }
+
+pub(crate) struct WindowsSubsystemParser;
+
+impl<S: Stage> SingleAttributeParser<S> for WindowsSubsystemParser {
+    const PATH: &[Symbol] = &[sym::windows_subsystem];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::CrateLevel;
+    const TEMPLATE: AttributeTemplate = template!(NameValueStr: ["windows", "console"], "https://doc.rust-lang.org/reference/runtime.html#the-windows_subsystem-attribute");
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let Some(nv) = args.name_value() else {
+            cx.expected_name_value(
+                args.span().unwrap_or(cx.inner_span),
+                Some(sym::windows_subsystem),
+            );
+            return None;
+        };
+
+        let kind = match nv.value_as_str() {
+            Some(sym::console) => WindowsSubsystemKind::Console,
+            Some(sym::windows) => WindowsSubsystemKind::Windows,
+            Some(_) | None => {
+                cx.expected_specific_argument_strings(nv.value_span, &[sym::console, sym::windows]);
+                return None;
+            }
+        };
+
+        Some(AttributeKind::WindowsSubsystem(kind, cx.attr_span))
+    }
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -28,6 +28,7 @@ use crate::attributes::confusables::ConfusablesParser;
 use crate::attributes::crate_level::{
     CrateNameParser, MoveSizeLimitParser, NoCoreParser, NoStdParser, PatternComplexityLimitParser,
     RecursionLimitParser, RustcCoherenceIsCoreParser, TypeLengthLimitParser,
+    WindowsSubsystemParser,
 };
 use crate::attributes::debugger::DebuggerViualizerParser;
 use crate::attributes::deprecation::DeprecationParser;
@@ -211,6 +212,7 @@ attribute_parsers!(
         Single<SkipDuringMethodDispatchParser>,
         Single<TransparencyParser>,
         Single<TypeLengthLimitParser>,
+        Single<WindowsSubsystemParser>,
         Single<WithoutArgs<AllowIncoherentImplParser>>,
         Single<WithoutArgs<AllowInternalUnsafeParser>>,
         Single<WithoutArgs<AsPtrParser>>,

compiler/rustc_codegen_ssa/messages.ftl

@@ -169,8 +169,6 @@ codegen_ssa_invalid_monomorphization_unsupported_symbol = invalid monomorphizati
 
 codegen_ssa_invalid_monomorphization_unsupported_symbol_of_size = invalid monomorphization of `{$name}` intrinsic: unsupported {$symbol} from `{$in_ty}` with element `{$in_elem}` of size `{$size}` to `{$ret_ty}`
 
-codegen_ssa_invalid_windows_subsystem = invalid windows subsystem `{$subsystem}`, only `windows` and `console` are allowed
-
 codegen_ssa_ld64_unimplemented_modifier = `as-needed` modifier not implemented yet for ld64
 
 codegen_ssa_lib_def_write_failure = failed to write lib.def file: {$error}

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2558,7 +2558,7 @@ fn add_order_independent_options(
         && sess.target.is_like_windows
         && let Some(s) = &codegen_results.crate_info.windows_subsystem
     {
-        cmd.subsystem(s);
+        cmd.windows_subsystem(*s);
     }
 
     // Try to strip as much out of the generated object by removing unused

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -5,6 +5,7 @@ use std::path::{Path, PathBuf};
 use std::{env, io, iter, mem, str};
 
 use find_msvc_tools;
+use rustc_hir::attrs::WindowsSubsystemKind;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_metadata::{
     find_native_static_library, try_find_native_dynamic_library, try_find_native_static_library,
@@ -345,7 +346,7 @@ pub(crate) trait Linker {
         crate_type: CrateType,
         symbols: &[(String, SymbolExportKind)],
     );
-    fn subsystem(&mut self, subsystem: &str);
+    fn windows_subsystem(&mut self, subsystem: WindowsSubsystemKind);
     fn linker_plugin_lto(&mut self);
     fn add_eh_frame_header(&mut self) {}
     fn add_no_exec(&mut self) {}
@@ -884,8 +885,8 @@ impl<'a> Linker for GccLinker<'a> {
         }
     }
 
-    fn subsystem(&mut self, subsystem: &str) {
-        self.link_args(&["--subsystem", subsystem]);
+    fn windows_subsystem(&mut self, subsystem: WindowsSubsystemKind) {
+        self.link_args(&["--subsystem", subsystem.as_str()]);
     }
 
     fn reset_per_library_state(&mut self) {
@@ -1159,9 +1160,8 @@ impl<'a> Linker for MsvcLinker<'a> {
         self.link_arg(&arg);
     }
 
-    fn subsystem(&mut self, subsystem: &str) {
-        // Note that previous passes of the compiler validated this subsystem,
-        // so we just blindly pass it to the linker.
+    fn windows_subsystem(&mut self, subsystem: WindowsSubsystemKind) {
+        let subsystem = subsystem.as_str();
         self.link_arg(&format!("/SUBSYSTEM:{subsystem}"));
 
         // Windows has two subsystems we're interested in right now, the console
@@ -1307,7 +1307,7 @@ impl<'a> Linker for EmLinker<'a> {
         self.cc_arg(arg);
     }
 
-    fn subsystem(&mut self, _subsystem: &str) {
+    fn windows_subsystem(&mut self, _subsystem: WindowsSubsystemKind) {
         // noop
     }
 
@@ -1444,7 +1444,7 @@ impl<'a> Linker for WasmLd<'a> {
         }
     }
 
-    fn subsystem(&mut self, _subsystem: &str) {}
+    fn windows_subsystem(&mut self, _subsystem: WindowsSubsystemKind) {}
 
     fn linker_plugin_lto(&mut self) {
         match self.sess.opts.cg.linker_plugin_lto {
@@ -1566,7 +1566,8 @@ impl<'a> Linker for L4Bender<'a> {
         self.sess.dcx().emit_warn(errors::L4BenderExportingSymbolsUnimplemented);
     }
 
-    fn subsystem(&mut self, subsystem: &str) {
+    fn windows_subsystem(&mut self, subsystem: WindowsSubsystemKind) {
+        let subsystem = subsystem.as_str();
         self.link_arg(&format!("--subsystem {subsystem}"));
     }
 
@@ -1735,7 +1736,7 @@ impl<'a> Linker for AixLinker<'a> {
         self.link_arg(format!("-bE:{}", path.to_str().unwrap()));
     }
 
-    fn subsystem(&mut self, _subsystem: &str) {}
+    fn windows_subsystem(&mut self, _subsystem: WindowsSubsystemKind) {}
 
     fn reset_per_library_state(&mut self) {
         self.hint_dynamic();
@@ -1969,7 +1970,7 @@ impl<'a> Linker for PtxLinker<'a> {
     ) {
     }
 
-    fn subsystem(&mut self, _subsystem: &str) {}
+    fn windows_subsystem(&mut self, _subsystem: WindowsSubsystemKind) {}
 
     fn linker_plugin_lto(&mut self) {}
 }
@@ -2050,7 +2051,7 @@ impl<'a> Linker for LlbcLinker<'a> {
         }
     }
 
-    fn subsystem(&mut self, _subsystem: &str) {}
+    fn windows_subsystem(&mut self, _subsystem: WindowsSubsystemKind) {}
 
     fn linker_plugin_lto(&mut self) {}
 }
@@ -2134,7 +2135,7 @@ impl<'a> Linker for BpfLinker<'a> {
         }
     }
 
-    fn subsystem(&mut self, _subsystem: &str) {}
+    fn windows_subsystem(&mut self, _subsystem: WindowsSubsystemKind) {}
 
     fn linker_plugin_lto(&mut self) {}
 }

compiler/rustc_codegen_ssa/src/base.rs

@@ -5,7 +5,6 @@ use std::time::{Duration, Instant};
 
 use itertools::Itertools;
 use rustc_abi::FIRST_VARIANT;
-use rustc_ast as ast;
 use rustc_ast::expand::allocator::{
     ALLOC_ERROR_HANDLER, ALLOCATOR_METHODS, AllocatorKind, AllocatorMethod, AllocatorTy,
 };
@@ -13,10 +12,10 @@ use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_data_structures::profiling::{get_resident_set_size, print_time_passes_entry};
 use rustc_data_structures::sync::{IntoDynSyncSend, par_map};
 use rustc_data_structures::unord::UnordMap;
-use rustc_hir::attrs::{DebuggerVisualizerType, OptimizeAttr};
-use rustc_hir::def_id::{DefId, LOCAL_CRATE};
+use rustc_hir::attrs::{AttributeKind, DebuggerVisualizerType, OptimizeAttr};
+use rustc_hir::def_id::{CRATE_DEF_ID, DefId, LOCAL_CRATE};
 use rustc_hir::lang_items::LangItem;
-use rustc_hir::{ItemId, Target};
+use rustc_hir::{ItemId, Target, find_attr};
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::dependency_format::Dependencies;
@@ -31,7 +30,7 @@ use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_session::Session;
 use rustc_session::config::{self, CrateType, EntryFnType};
-use rustc_span::{DUMMY_SP, Symbol, sym};
+use rustc_span::{DUMMY_SP, Symbol};
 use rustc_symbol_mangling::mangle_internal_symbol;
 use rustc_target::spec::{Arch, Os};
 use rustc_trait_selection::infer::{BoundRegionConversionTime, TyCtxtInferExt};
@@ -896,15 +895,7 @@ impl CrateInfo {
         let linked_symbols =
             crate_types.iter().map(|&c| (c, crate::back::linker::linked_symbols(tcx, c))).collect();
         let local_crate_name = tcx.crate_name(LOCAL_CRATE);
-        let crate_attrs = tcx.hir_attrs(rustc_hir::CRATE_HIR_ID);
-        let subsystem =
-            ast::attr::first_attr_value_str_by_name(crate_attrs, sym::windows_subsystem);
-        let windows_subsystem = subsystem.map(|subsystem| {
-            if subsystem != sym::windows && subsystem != sym::console {
-                tcx.dcx().emit_fatal(errors::InvalidWindowsSubsystem { subsystem });
-            }
-            subsystem.to_string()
-        });
+        let windows_subsystem = find_attr!(tcx.get_all_attrs(CRATE_DEF_ID), AttributeKind::WindowsSubsystem(kind, _) => *kind);
 
         // This list is used when generating the command line to pass through to
         // system linker. The linker expects undefined symbols on the left of the

compiler/rustc_codegen_ssa/src/errors.rs

@@ -749,12 +749,6 @@ pub(crate) struct MultipleMainFunctions {
     pub span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(codegen_ssa_invalid_windows_subsystem)]
-pub(crate) struct InvalidWindowsSubsystem {
-    pub subsystem: Symbol,
-}
-
 #[derive(Diagnostic)]
 #[diag(codegen_ssa_shuffle_indices_evaluation)]
 pub(crate) struct ShuffleIndicesEvaluation {

compiler/rustc_codegen_ssa/src/lib.rs

@@ -24,7 +24,7 @@ use std::sync::Arc;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::unord::UnordMap;
 use rustc_hir::CRATE_HIR_ID;
-use rustc_hir::attrs::{CfgEntry, NativeLibKind};
+use rustc_hir::attrs::{CfgEntry, NativeLibKind, WindowsSubsystemKind};
 use rustc_hir::def_id::CrateNum;
 use rustc_macros::{Decodable, Encodable, HashStable};
 use rustc_metadata::EncodedMetadata;
@@ -225,7 +225,7 @@ pub struct CrateInfo {
     pub used_crate_source: UnordMap<CrateNum, Arc<CrateSource>>,
     pub used_crates: Vec<CrateNum>,
     pub dependency_formats: Arc<Dependencies>,
-    pub windows_subsystem: Option<String>,
+    pub windows_subsystem: Option<WindowsSubsystemKind>,
     pub natvis_debugger_visualizers: BTreeSet<DebuggerVisualizerFile>,
     pub lint_levels: CodegenLintLevels,
     pub metadata_symbol: String,

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -404,6 +404,22 @@ pub enum RtsanSetting {
     Caller,
 }
 
+#[derive(Eq, PartialEq, Debug, Copy, Clone)]
+#[derive(Encodable, Decodable, HashStable_Generic, PrintAttribute)]
+pub enum WindowsSubsystemKind {
+    Console,
+    Windows,
+}
+
+impl WindowsSubsystemKind {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            WindowsSubsystemKind::Console => "console",
+            WindowsSubsystemKind::Windows => "windows",
+        }
+    }
+}
+
 /// Represents parsed *built-in* inert attributes.
 ///
 /// ## Overview
@@ -759,5 +775,8 @@ pub enum AttributeKind {
 
     /// Represents `#[used]`
     Used { used_by: UsedBy, span: Span },
+
+    /// Represents `#[windows_subsystem]`.
+    WindowsSubsystem(WindowsSubsystemKind, Span),
     // tidy-alphabetical-end
 }

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -106,6 +106,7 @@ impl AttributeKind {
             UnsafeSpecializationMarker(..) => No,
             UnstableFeatureBound(..) => No,
             Used { .. } => No,
+            WindowsSubsystem(..) => No,
             // tidy-alphabetical-end
         }
     }

compiler/rustc_passes/src/check_attr.rs

@@ -287,7 +287,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::DebuggerVisualizer(..)
                     | AttributeKind::RustcMain
                     | AttributeKind::RustcPassIndirectlyInNonRusticAbis(..)
-                    | AttributeKind::PinV2(..),
+                    | AttributeKind::PinV2(..)
+                    | AttributeKind::WindowsSubsystem(..)
                 ) => { /* do nothing  */ }
                 Attribute::Unparsed(attr_item) => {
                     style = Some(attr_item.style);
@@ -361,7 +362,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             // need to be fixed
                             | sym::cfi_encoding // FIXME(cfi_encoding)
                             | sym::instruction_set // broken on stable!!!
-                            | sym::windows_subsystem // broken on stable!!!
                             | sym::patchable_function_entry // FIXME(patchable_function_entry)
                             | sym::deprecated_safe // FIXME(deprecated_safe)
                             // internal

tests/ui/attributes/malformed-attrs.stderr

@@ -26,20 +26,6 @@ error[E0463]: can't find crate for `wloop`
 LL | extern crate wloop;
    | ^^^^^^^^^^^^^^^^^^^ can't find crate
 
-error: malformed `windows_subsystem` attribute input
-  --> $DIR/malformed-attrs.rs:26:1
-   |
-LL | #![windows_subsystem]
-   | ^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: for more information, visit <https://doc.rust-lang.org/reference/runtime.html#the-windows_subsystem-attribute>
-help: the following are the possible correct uses
-   |
-LL | #![windows_subsystem = "console"]
-   |                      +++++++++++
-LL | #![windows_subsystem = "windows"]
-   |                      +++++++++++
-
 error: malformed `instruction_set` attribute input
   --> $DIR/malformed-attrs.rs:112:1
    |
@@ -217,6 +203,22 @@ LL | #[doc]
    = note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
    = note: for more information, visit <https://doc.rust-lang.org/rustdoc/write-documentation/the-doc-attribute.html>
 
+error[E0539]: malformed `windows_subsystem` attribute input
+  --> $DIR/malformed-attrs.rs:26:1
+   |
+LL | #![windows_subsystem]
+   | ^^^-----------------^
+   |    |
+   |    expected this to be of the form `windows_subsystem = "..."`
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/reference/runtime.html#the-windows_subsystem-attribute>
+help: try changing it to one of the following valid forms of the attribute
+   |
+LL | #![windows_subsystem = "console"]
+   |                      +++++++++++
+LL | #![windows_subsystem = "windows"]
+   |                      +++++++++++
+
 error[E0539]: malformed `export_name` attribute input
   --> $DIR/malformed-attrs.rs:29:1
    |

tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.rs

@@ -814,26 +814,26 @@ mod must_use {
 
 #[windows_subsystem = "windows"]
 //~^ WARN crate-level attribute should be an inner attribute
-//~| HELP add a `!`
 mod windows_subsystem {
+    //~^ NOTE This attribute does not have an `!`, which means it is applied to this module
     mod inner { #![windows_subsystem="windows"] }
-    //~^ WARN crate-level attribute should be in the root module
+    //~^ WARN the `#![windows_subsystem]` attribute can only be used at the crate root
 
     #[windows_subsystem = "windows"] fn f() { }
     //~^ WARN crate-level attribute should be an inner attribute
-    //~| HELP add a `!`
+    //~| NOTE This attribute does not have an `!`, which means it is applied to this function
 
     #[windows_subsystem = "windows"] struct S;
     //~^ WARN crate-level attribute should be an inner attribute
-    //~| HELP add a `!`
+    //~| NOTE This attribute does not have an `!`, which means it is applied to this struct
 
     #[windows_subsystem = "windows"] type T = S;
     //~^ WARN crate-level attribute should be an inner attribute
-    //~| HELP add a `!`
+    //~| NOTE This attribute does not have an `!`, which means it is applied to this type alias
 
     #[windows_subsystem = "windows"] impl S { }
     //~^ WARN crate-level attribute should be an inner attribute
-    //~| HELP add a `!`
+    //~| NOTE This attribute does not have an `!`, which means it is applied to this implementation block
 }
 
 // BROKEN USES OF CRATE-LEVEL BUILT-IN ATTRIBUTES

tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.stderr

@@ -218,17 +218,6 @@ LL | | }
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
-warning: crate-level attribute should be an inner attribute
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:815:1
-   |
-LL | #[windows_subsystem = "windows"]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: add a `!`
-   |
-LL | #![windows_subsystem = "windows"]
-   |  +
-
 warning: crate-level attribute should be an inner attribute
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:865:1
    |
@@ -387,56 +376,6 @@ LL |     #[link(name = "x")] extern "Rust" {}
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
-warning: crate-level attribute should be in the root module
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:819:17
-   |
-LL |     mod inner { #![windows_subsystem="windows"] }
-   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-warning: crate-level attribute should be an inner attribute
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:822:5
-   |
-LL |     #[windows_subsystem = "windows"] fn f() { }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: add a `!`
-   |
-LL |     #![windows_subsystem = "windows"] fn f() { }
-   |      +
-
-warning: crate-level attribute should be an inner attribute
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:826:5
-   |
-LL |     #[windows_subsystem = "windows"] struct S;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: add a `!`
-   |
-LL |     #![windows_subsystem = "windows"] struct S;
-   |      +
-
-warning: crate-level attribute should be an inner attribute
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:830:5
-   |
-LL |     #[windows_subsystem = "windows"] type T = S;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: add a `!`
-   |
-LL |     #![windows_subsystem = "windows"] type T = S;
-   |      +
-
-warning: crate-level attribute should be an inner attribute
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:834:5
-   |
-LL |     #[windows_subsystem = "windows"] impl S { }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: add a `!`
-   |
-LL |     #![windows_subsystem = "windows"] impl S { }
-   |      +
-
 warning: crate-level attribute should be in the root module
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:869:17
    |
@@ -1319,6 +1258,76 @@ LL |     #[must_use] impl S { }
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = help: `#[must_use]` can be applied to data types, functions, traits, and unions
 
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![windows_subsystem]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:815:1
+   |
+LL | #[windows_subsystem = "windows"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: This attribute does not have an `!`, which means it is applied to this module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:817:1
+   |
+LL | / mod windows_subsystem {
+LL | |
+LL | |     mod inner { #![windows_subsystem="windows"] }
+...  |
+LL | | }
+   | |_^
+
+warning: the `#![windows_subsystem]` attribute can only be used at the crate root
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:819:17
+   |
+LL |     mod inner { #![windows_subsystem="windows"] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![windows_subsystem]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:822:5
+   |
+LL |     #[windows_subsystem = "windows"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: This attribute does not have an `!`, which means it is applied to this function
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:822:38
+   |
+LL |     #[windows_subsystem = "windows"] fn f() { }
+   |                                      ^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![windows_subsystem]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:826:5
+   |
+LL |     #[windows_subsystem = "windows"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: This attribute does not have an `!`, which means it is applied to this struct
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:826:38
+   |
+LL |     #[windows_subsystem = "windows"] struct S;
+   |                                      ^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![windows_subsystem]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:830:5
+   |
+LL |     #[windows_subsystem = "windows"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: This attribute does not have an `!`, which means it is applied to this type alias
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:830:38
+   |
+LL |     #[windows_subsystem = "windows"] type T = S;
+   |                                      ^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![windows_subsystem]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:834:5
+   |
+LL |     #[windows_subsystem = "windows"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: This attribute does not have an `!`, which means it is applied to this implementation block
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:834:38
+   |
+LL |     #[windows_subsystem = "windows"] impl S { }
+   |                                      ^^^^^^^^^^
+
 warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![crate_name]`
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:841:1
    |

tests/ui/lint/unused/unused-attr-duplicate.stderr

@@ -28,19 +28,6 @@ note: attribute also specified here
 LL | #[no_link]
    | ^^^^^^^^^^
 
-error: unused attribute
-  --> $DIR/unused-attr-duplicate.rs:31:1
-   |
-LL | #![windows_subsystem = "windows"]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
-   |
-note: attribute also specified here
-  --> $DIR/unused-attr-duplicate.rs:30:1
-   |
-LL | #![windows_subsystem = "console"]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-
 error: unused attribute
   --> $DIR/unused-attr-duplicate.rs:34:1
    |
@@ -316,5 +303,18 @@ note: attribute also specified here
 LL | #![no_implicit_prelude]
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
+error: unused attribute
+  --> $DIR/unused-attr-duplicate.rs:31:1
+   |
+LL | #![windows_subsystem = "windows"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
+  --> $DIR/unused-attr-duplicate.rs:30:1
+   |
+LL | #![windows_subsystem = "console"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
 error: aborting due to 25 previous errors
 

tests/ui/windows-subsystem/windows-subsystem-invalid.rs

@@ -1,5 +1,4 @@
 #![windows_subsystem = "wrong"]
+//~^ ERROR malformed `windows_subsystem` attribute input [E0539]
 
 fn main() {}
-
-//~? ERROR invalid windows subsystem `wrong`

tests/ui/windows-subsystem/windows-subsystem-invalid.stderr

@@ -1,4 +1,21 @@
-error: invalid windows subsystem `wrong`, only `windows` and `console` are allowed
+error[E0539]: malformed `windows_subsystem` attribute input
+  --> $DIR/windows-subsystem-invalid.rs:1:1
+   |
+LL | #![windows_subsystem = "wrong"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^-------^
+   |                        |
+   |                        valid arguments are "console" or "windows"
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/reference/runtime.html#the-windows_subsystem-attribute>
+help: try changing it to one of the following valid forms of the attribute
+   |
+LL - #![windows_subsystem = "wrong"]
+LL + #![windows_subsystem = "console"]
+   |
+LL - #![windows_subsystem = "wrong"]
+LL + #![windows_subsystem = "windows"]
+   |
 
 error: aborting due to 1 previous error
 
+For more information about this error, try `rustc --explain E0539`.