3 files changed, 435 insertions, 4 deletions

diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 228d706db..c64b78445 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -23,7 +23,7 @@ use crate::{
 };
 
 /// Holds documentation
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Documentation(String);
 
 impl Documentation {
@@ -32,9 +32,9 @@ impl Documentation {
     }
 }
 
-impl Into<String> for Documentation {
-    fn into(self) -> String {
-        self.0
+impl From<Documentation> for String {
+    fn from(Documentation(string): Documentation) -> Self {
+        string
     }
 }
 
diff --git a/crates/hir_def/src/builtin_attr.rs b/crates/hir_def/src/builtin_attr.rs
new file mode 100644
index 000000000..2e989c504
--- /dev/null
+++ b/crates/hir_def/src/builtin_attr.rs
@@ -0,0 +1,430 @@
+//! Builtin attributes resolved by nameres.
+//!
+//! The actual definitions were copied from rustc's `compiler/rustc_feature/src/builtin_attrs.rs`.
+//!
+//! It was last synchronized with upstream commit 2225ee1b62ff089917434aefd9b2bf509cfa087f.
+//!
+//! The macros were adjusted to only expand to the attribute name, since that is all we need to do
+//! name resolution, and `BUILTIN_ATTRIBUTES` is almost entirely unchanged from the original, to
+//! ease updating.
+
+/// Ignored attribute namespaces used by tools.
+pub const TOOL_MODULES: &[&str] = &["rustfmt", "clippy"];
+
+type BuiltinAttribute = &'static str;
+
+macro_rules! ungated {
+    ($attr:ident, $typ:expr, $tpl:expr $(,)?) => {
+        stringify!($attr)
+    };
+}
+
+macro_rules! gated {
+    ($attr:ident $($rest:tt)*) => {
+        stringify!($attr)
+    };
+}
+
+macro_rules! rustc_attr {
+    (TEST, $attr:ident $($rest:tt)*) => {
+        stringify!($attr)
+    };
+    ($attr:ident $($rest:tt)*) => {
+        stringify!($attr)
+    };
+}
+
+/// Attributes that have a special meaning to rustc or rustdoc.
+#[rustfmt::skip]
+pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
+    // ==========================================================================
+    // Stable attributes:
+    // ==========================================================================
+
+    // Conditional compilation:
+    ungated!(cfg, Normal, template!(List: "predicate")),
+    ungated!(cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ...")),
+
+    // Testing:
+    ungated!(ignore, Normal, template!(Word, NameValueStr: "reason")),
+    ungated!(
+        should_panic, Normal,
+        template!(Word, List: r#"expected = "reason"#, NameValueStr: "reason"),
+    ),
+    // FIXME(Centril): This can be used on stable but shouldn't.
+    ungated!(reexport_test_harness_main, Normal, template!(NameValueStr: "name")),
+
+    // Macros:
+    ungated!(derive, Normal, template!(List: "Trait1, Trait2, ...")),
+    ungated!(automatically_derived, Normal, template!(Word)),
+    // FIXME(#14407)
+    ungated!(macro_use, Normal, template!(Word, List: "name1, name2, ...")),
+    ungated!(macro_escape, Normal, template!(Word)), // Deprecated synonym for `macro_use`.
+    ungated!(macro_export, Normal, template!(Word, List: "local_inner_macros")),
+    ungated!(proc_macro, Normal, template!(Word)),
+    ungated!(
+        proc_macro_derive, Normal,
+        template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)"),
+    ),
+    ungated!(proc_macro_attribute, Normal, template!(Word)),
+
+    // Lints:
+    ungated!(warn, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(allow, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(must_use, AssumedUsed, template!(Word, NameValueStr: "reason")),
+    // FIXME(#14407)
+    ungated!(
+        deprecated, Normal,
+        template!(
+            Word,
+            List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#,
+            NameValueStr: "reason"
+        ),
+    ),
+
+    // Crate properties:
+    ungated!(crate_name, CrateLevel, template!(NameValueStr: "name")),
+    ungated!(crate_type, CrateLevel, template!(NameValueStr: "bin|lib|...")),
+    ungated!(crate_id, CrateLevel, template!(NameValueStr: "ignored")),
+
+    // ABI, linking, symbols, and FFI
+    ungated!(
+        link, AssumedUsed,
+        template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...""#),
+    ),
+    ungated!(link_name, AssumedUsed, template!(NameValueStr: "name")),
+    ungated!(no_link, Normal, template!(Word)),
+    ungated!(repr, Normal, template!(List: "C")),
+    ungated!(export_name, AssumedUsed, template!(NameValueStr: "name")),
+    ungated!(link_section, AssumedUsed, template!(NameValueStr: "name")),
+    ungated!(no_mangle, AssumedUsed, template!(Word)),
+    ungated!(used, AssumedUsed, template!(Word)),
+
+    // Limits:
+    ungated!(recursion_limit, CrateLevel, template!(NameValueStr: "N")),
+    ungated!(type_length_limit, CrateLevel, template!(NameValueStr: "N")),
+    gated!(
+        const_eval_limit, CrateLevel, template!(NameValueStr: "N"), const_eval_limit,
+        experimental!(const_eval_limit)
+    ),
+
+    // Entry point:
+    ungated!(main, Normal, template!(Word)),
+    ungated!(start, Normal, template!(Word)),
+    ungated!(no_start, CrateLevel, template!(Word)),
+    ungated!(no_main, CrateLevel, template!(Word)),
+
+    // Modules, prelude, and resolution:
+    ungated!(path, Normal, template!(NameValueStr: "file")),
+    ungated!(no_std, CrateLevel, template!(Word)),
+    ungated!(no_implicit_prelude, Normal, template!(Word)),
+    ungated!(non_exhaustive, AssumedUsed, template!(Word)),
+
+    // Runtime
+    ungated!(windows_subsystem, AssumedUsed, template!(NameValueStr: "windows|console")),
+    ungated!(panic_handler, Normal, template!(Word)), // RFC 2070
+
+    // Code generation:
+    ungated!(inline, AssumedUsed, template!(Word, List: "always|never")),
+    ungated!(cold, AssumedUsed, template!(Word)),
+    ungated!(no_builtins, AssumedUsed, template!(Word)),
+    ungated!(target_feature, AssumedUsed, template!(List: r#"enable = "name""#)),
+    ungated!(track_caller, AssumedUsed, template!(Word)),
+    gated!(
+        no_sanitize, AssumedUsed,
+        template!(List: "address, memory, thread"),
+        experimental!(no_sanitize)
+    ),
+
+    // FIXME: #14408 assume docs are used since rustdoc looks at them.
+    ungated!(doc, AssumedUsed, template!(List: "hidden|inline|...", NameValueStr: "string")),
+
+    // ==========================================================================
+    // Unstable attributes:
+    // ==========================================================================
+
+    // Linking:
+    gated!(naked, AssumedUsed, template!(Word), naked_functions, experimental!(naked)),
+    gated!(
+        link_args, Normal, template!(NameValueStr: "args"),
+        "the `link_args` attribute is experimental and not portable across platforms, \
+        it is recommended to use `#[link(name = \"foo\")] instead",
+    ),
+    gated!(
+        link_ordinal, AssumedUsed, template!(List: "ordinal"), raw_dylib,
+        experimental!(link_ordinal)
+    ),
+
+    // Plugins:
+    // XXX Modified for use in rust-analyzer
+    gated!(plugin_registrar),
+    gated!(plugin),
+
+    // Testing:
+    gated!(allow_fail, Normal, template!(Word), experimental!(allow_fail)),
+    gated!(
+        test_runner, CrateLevel, template!(List: "path"), custom_test_frameworks,
+        "custom test frameworks are an unstable feature",
+    ),
+    // RFC #1268
+    gated!(marker, Normal, template!(Word), marker_trait_attr, experimental!(marker)),
+    gated!(
+        thread_local, AssumedUsed, template!(Word),
+        "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
+    ),
+    gated!(no_core, CrateLevel, template!(Word), experimental!(no_core)),
+    // RFC 2412
+    gated!(
+        optimize, AssumedUsed, template!(List: "size|speed"), optimize_attribute,
+        experimental!(optimize),
+    ),
+    // RFC 2867
+    gated!(instruction_set, AssumedUsed, template!(List: "set"), isa_attribute, experimental!(instruction_set)),
+
+    gated!(ffi_returns_twice, AssumedUsed, template!(Word), experimental!(ffi_returns_twice)),
+    gated!(ffi_pure, AssumedUsed, template!(Word), experimental!(ffi_pure)),
+    gated!(ffi_const, AssumedUsed, template!(Word), experimental!(ffi_const)),
+    gated!(
+        register_attr, CrateLevel, template!(List: "attr1, attr2, ..."),
+        experimental!(register_attr),
+    ),
+    gated!(
+        register_tool, CrateLevel, template!(List: "tool1, tool2, ..."),
+        experimental!(register_tool),
+    ),
+
+    gated!(cmse_nonsecure_entry, AssumedUsed, template!(Word), experimental!(cmse_nonsecure_entry)),
+
+    // ==========================================================================
+    // Internal attributes: Stability, deprecation, and unsafe:
+    // ==========================================================================
+
+    ungated!(feature, CrateLevel, template!(List: "name1, name1, ...")),
+    // FIXME(#14407) -- only looked at on-demand so we can't
+    // guarantee they'll have already been checked.
+    ungated!(
+        rustc_deprecated, AssumedUsed,
+        template!(List: r#"since = "version", reason = "...""#)
+    ),
+    // FIXME(#14407)
+    ungated!(stable, AssumedUsed, template!(List: r#"feature = "name", since = "version""#)),
+    // FIXME(#14407)
+    ungated!(
+        unstable, AssumedUsed,
+        template!(List: r#"feature = "name", reason = "...", issue = "N""#),
+    ),
+    // FIXME(#14407)
+    ungated!(rustc_const_unstable, AssumedUsed, template!(List: r#"feature = "name""#)),
+    // FIXME(#14407)
+    ungated!(rustc_const_stable, AssumedUsed, template!(List: r#"feature = "name""#)),
+    gated!(
+        allow_internal_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
+        "allow_internal_unstable side-steps feature gating and stability checks",
+    ),
+    gated!(
+        rustc_allow_const_fn_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
+        "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
+    ),
+    gated!(
+        allow_internal_unsafe, Normal, template!(Word),
+        "allow_internal_unsafe side-steps the unsafe_code lint",
+    ),
+
+    // ==========================================================================
+    // Internal attributes: Type system related:
+    // ==========================================================================
+
+    gated!(fundamental, AssumedUsed, template!(Word), experimental!(fundamental)),
+    gated!(
+        may_dangle, Normal, template!(Word), dropck_eyepatch,
+        "`may_dangle` has unstable semantics and may be removed in the future",
+    ),
+
+    // ==========================================================================
+    // Internal attributes: Runtime related:
+    // ==========================================================================
+
+    rustc_attr!(rustc_allocator, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_allocator_nounwind, AssumedUsed, template!(Word), IMPL_DETAIL),
+    gated!(alloc_error_handler, Normal, template!(Word), experimental!(alloc_error_handler)),
+    gated!(
+        default_lib_allocator, AssumedUsed, template!(Word), allocator_internals,
+        experimental!(default_lib_allocator),
+    ),
+    gated!(
+        needs_allocator, Normal, template!(Word), allocator_internals,
+        experimental!(needs_allocator),
+    ),
+    gated!(panic_runtime, AssumedUsed, template!(Word), experimental!(panic_runtime)),
+    gated!(needs_panic_runtime, AssumedUsed, template!(Word), experimental!(needs_panic_runtime)),
+    gated!(
+        unwind, AssumedUsed, template!(List: "allowed|aborts"), unwind_attributes,
+        experimental!(unwind),
+    ),
+    gated!(
+        compiler_builtins, AssumedUsed, template!(Word),
+        "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
+        which contains compiler-rt intrinsics and will never be stable",
+    ),
+    gated!(
+        profiler_runtime, AssumedUsed, template!(Word),
+        "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
+        which contains the profiler runtime and will never be stable",
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Linkage:
+    // ==========================================================================
+
+    gated!(
+        linkage, AssumedUsed, template!(NameValueStr: "external|internal|..."),
+        "the `linkage` attribute is experimental and not portable across platforms",
+    ),
+    rustc_attr!(rustc_std_internal_symbol, AssumedUsed, template!(Word), INTERNAL_UNSTABLE),
+
+    // ==========================================================================
+    // Internal attributes, Macro related:
+    // ==========================================================================
+
+    rustc_attr!(rustc_builtin_macro, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), INTERNAL_UNSTABLE),
+    rustc_attr!(
+        rustc_macro_transparency, AssumedUsed,
+        template!(NameValueStr: "transparent|semitransparent|opaque"),
+        "used internally for testing macro hygiene",
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Diagnostics related:
+    // ==========================================================================
+
+    rustc_attr!(
+        rustc_on_unimplemented, AssumedUsed,
+        template!(
+            List: r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#,
+            NameValueStr: "message"
+        ),
+        INTERNAL_UNSTABLE
+    ),
+    // Enumerates "identity-like" conversion methods to suggest on type mismatch.
+    rustc_attr!(rustc_conversion_suggestion, AssumedUsed, template!(Word), INTERNAL_UNSTABLE),
+
+    // ==========================================================================
+    // Internal attributes, Const related:
+    // ==========================================================================
+
+    rustc_attr!(rustc_promotable, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_args_required_const, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
+
+    // ==========================================================================
+    // Internal attributes, Layout related:
+    // ==========================================================================
+
+    rustc_attr!(
+        rustc_layout_scalar_valid_range_start, AssumedUsed, template!(List: "value"),
+        "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
+        niche optimizations in libcore and will never be stable",
+    ),
+    rustc_attr!(
+        rustc_layout_scalar_valid_range_end, AssumedUsed, template!(List: "value"),
+        "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
+        niche optimizations in libcore and will never be stable",
+    ),
+    rustc_attr!(
+        rustc_nonnull_optimization_guaranteed, AssumedUsed, template!(Word),
+        "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \
+        niche optimizations in libcore and will never be stable",
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Misc:
+    // ==========================================================================
+    gated!(
+        lang, Normal, template!(NameValueStr: "name"), lang_items,
+        "language items are subject to change",
+    ),
+    gated!(rustc_diagnostic_item), // XXX modified in rust-analyzer
+    gated!(
+        // Used in resolve:
+        prelude_import, AssumedUsed, template!(Word),
+        "`#[prelude_import]` is for use by rustc only",
+    ),
+    gated!(
+        rustc_paren_sugar, Normal, template!(Word), unboxed_closures,
+        "unboxed_closures are still evolving",
+    ),
+    rustc_attr!(
+        rustc_inherit_overflow_checks, AssumedUsed, template!(Word),
+        "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
+        overflow checking behavior of several libcore functions that are inlined \
+        across crates and will never be stable",
+    ),
+    rustc_attr!(rustc_reservation_impl, Normal, template!(NameValueStr: "reservation message"),
+                "the `#[rustc_reservation_impl]` attribute is internally used \
+                 for reserving for `for<T> From<!> for T` impl"
+    ),
+    rustc_attr!(
+        rustc_test_marker, Normal, template!(Word),
+        "the `#[rustc_test_marker]` attribute is used internally to track tests",
+    ),
+    rustc_attr!(
+        rustc_unsafe_specialization_marker, Normal, template!(Word),
+        "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations"
+    ),
+    rustc_attr!(
+        rustc_specialization_trait, Normal, template!(Word),
+        "the `#[rustc_specialization_trait]` attribute is used to check specializations"
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Testing:
+    // ==========================================================================
+
+    rustc_attr!(TEST, rustc_outlives, Normal, template!(Word)),
+    rustc_attr!(TEST, rustc_capture_analysis, Normal, template!(Word)),
+    rustc_attr!(TEST, rustc_variance, Normal, template!(Word)),
+    rustc_attr!(TEST, rustc_layout, Normal, template!(List: "field1, field2, ...")),
+    rustc_attr!(TEST, rustc_regions, Normal, template!(Word)),
+    rustc_attr!(
+        TEST, rustc_error, AssumedUsed,
+        template!(Word, List: "delay_span_bug_from_inside_query")
+    ),
+    rustc_attr!(TEST, rustc_dump_user_substs, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_if_this_changed, AssumedUsed, template!(Word, List: "DepNode")),
+    rustc_attr!(TEST, rustc_then_this_would_need, AssumedUsed, template!(List: "DepNode")),
+    rustc_attr!(
+        TEST, rustc_dirty, AssumedUsed,
+        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_clean, AssumedUsed,
+        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_partition_reused, AssumedUsed,
+        template!(List: r#"cfg = "...", module = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_partition_codegened, AssumedUsed,
+        template!(List: r#"cfg = "...", module = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_expected_cgu_reuse, AssumedUsed,
+        template!(List: r#"cfg = "...", module = "...", kind = "...""#),
+    ),
+    rustc_attr!(TEST, rustc_synthetic, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_symbol_name, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_polymorphize_error, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_def_path, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_mir, AssumedUsed, template!(List: "arg1, arg2, ...")),
+    rustc_attr!(TEST, rustc_dump_program_clauses, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_dump_env_program_clauses, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_object_lifetime_default, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/)),
+    gated!(
+        omit_gdb_pretty_printer_section, AssumedUsed, template!(Word),
+        "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite",
+    ),
+];
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index a1bbc729f..7e2199a9c 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -18,6 +18,7 @@ pub mod attr;
 pub mod path;
 pub mod type_ref;
 pub mod builtin_type;
+pub mod builtin_attr;
 pub mod diagnostics;
 pub mod per_ns;
 pub mod item_scope;