Add a future incompat warning for #[no_link]

compiler/rustc_attr_parsing/src/attributes/no_link.rs

@@ -1,6 +1,8 @@
 use rustc_feature::AttributeStability;
+use rustc_lint_defs::builtin::NO_LINK_ATTRIBUTES;
 
 use super::prelude::*;
+use crate::diagnostics::NoLinkAttrUsed;
 
 pub(crate) struct NoLinkParser;
 impl NoArgsAttributeParser for NoLinkParser {
@@ -14,4 +16,8 @@ impl NoArgsAttributeParser for NoLinkParser {
     ]);
     const STABILITY: AttributeStability = AttributeStability::Stable;
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::NoLink;
+
+    fn finalize_check(cx: &mut FinalizeCheckContext<'_, '_>, attr_span: Span) {
+        cx.emit_lint(NO_LINK_ATTRIBUTES, NoLinkAttrUsed, attr_span);
+    }
 }

compiler/rustc_attr_parsing/src/diagnostics.rs

@@ -2132,3 +2132,7 @@ pub(crate) enum MacroExport {
     #[note("declarative macros follow the same exporting rules as regular items")]
     OnDeclMacro,
 }
+
+#[derive(Diagnostic)]
+#[diag("use of deprecated `no_link` attribute")]
+pub(crate) struct NoLinkAttrUsed;

compiler/rustc_lint_defs/src/builtin.rs

@@ -83,6 +83,7 @@ pub mod hardwired {
             NEVER_TYPE_FALLBACK_FLOWING_INTO_UNSAFE,
             NON_CONTIGUOUS_RANGE_ENDPOINTS,
             NON_EXHAUSTIVE_OMITTED_PATTERNS,
+            NO_LINK_ATTRIBUTES,
             OUT_OF_SCOPE_MACRO_CALLS,
             OVERLAPPING_RANGE_ENDPOINTS,
             PARTIAL_STACK_PROTECTOR,
@@ -6019,3 +6020,35 @@ declare_lint! {
     r#"detects default field values on types that have const parameters"#,
     @feature_gate = default_field_values;
 }
+
+declare_lint! {
+    /// The `no_link_attributes` lint detects that you used `#[no_link]` on an
+    /// `extern crate` item.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #[no_link]
+    /// extern crate std;
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// This is a pre-1.0 attribute that accidentally got stabilized. It was only meant
+    /// for compiler plugins which we no longer support, not for regular crates. It is
+    /// rather fragile and can easily lead to linker errors depending on where rustc
+    /// decides to codegen functions and statics, which varies between rustc versions. It
+    /// might also be unsound if a crate for example expects a global constructor it
+    /// defined to run. Using it doesn't have an effect on the size of the produced
+    /// binaries except when it defines a `#[used]` static given that we remove all unused
+    /// functions and statics at link time already.
+    pub NO_LINK_ATTRIBUTES,
+    Deny,
+    "detects usage of `#[no_link]` on `extern crate` items",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: fcw!(FutureReleaseError #164032),
+        report_in_deps: true,
+    };
+}

tests/ui/attributes/malformed-attrs.rs

@@ -207,6 +207,8 @@ static mut TLS: u8 = 42;
 
 #[no_link()]
 //~^ ERROR malformed
+//~| ERROR use of deprecated `no_link` attribute
+//~| WARN this was previously accepted by the compiler
 #[macro_use = 1]
 //~^ ERROR malformed
 extern crate wloop;

tests/ui/attributes/malformed-attrs.stderr

@@ -23,7 +23,7 @@ LL | #[cfg_attr(predicate, attr1, attr2, ...)]
    |           ++++++++++++++++++++++++++++++
 
 error[E0463]: can't find crate for `wloop`
-  --> $DIR/malformed-attrs.rs:212:1
+  --> $DIR/malformed-attrs.rs:214:1
    |
 LL | extern crate wloop;
    | ^^^^^^^^^^^^^^^^^^^ can't find crate
@@ -783,7 +783,7 @@ LL + #[no_link]
    |
 
 error[E0539]: malformed `macro_use` attribute input
-  --> $DIR/malformed-attrs.rs:210:3
+  --> $DIR/malformed-attrs.rs:212:3
    |
 LL | #[macro_use = 1]
    |   ^^^^^^^^^^---
@@ -801,7 +801,7 @@ LL + #[macro_use(name1, name2, ...)]
    |
 
 error[E0539]: malformed `macro_export` attribute input
-  --> $DIR/malformed-attrs.rs:215:3
+  --> $DIR/malformed-attrs.rs:217:3
    |
 LL | #[macro_export = 18]
    |   ^^^^^^^^^^^^^----
@@ -818,7 +818,7 @@ LL + #[macro_export(local_inner_macros)]
    |
 
 error[E0658]: the `allow_internal_unsafe` attribute side-steps the `unsafe_code` lint
-  --> $DIR/malformed-attrs.rs:217:3
+  --> $DIR/malformed-attrs.rs:219:3
    |
 LL | #[allow_internal_unsafe = 1]
    |   ^^^^^^^^^^^^^^^^^^^^^
@@ -827,7 +827,7 @@ LL | #[allow_internal_unsafe = 1]
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0565]: malformed `allow_internal_unsafe` attribute input
-  --> $DIR/malformed-attrs.rs:217:3
+  --> $DIR/malformed-attrs.rs:219:3
    |
 LL | #[allow_internal_unsafe = 1]
    |   ^^^^^^^^^^^^^^^^^^^^^^---
@@ -964,8 +964,18 @@ LL | #[automatically_derived = 18]
    = help: the `automatically_derived` attribute can only be applied to trait impl blocks
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
+error: use of deprecated `no_link` attribute
+  --> $DIR/malformed-attrs.rs:208:1
+   |
+LL | #[no_link()]
+   | ^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
+   = note: `#[deny(no_link_attributes)]` (part of `#[deny(future_incompatible)]`) on by default
+
 error: valid forms for the attribute are `ignore` and `ignore = "reason"`
-  --> $DIR/malformed-attrs.rs:224:3
+  --> $DIR/malformed-attrs.rs:226:3
    |
 LL | #[ignore = 1]
    |   ^^^^^^^^^^
@@ -984,7 +994,7 @@ LL |     #[coroutine = 63] || {}
    = note: expected unit type `()`
               found coroutine `{coroutine@$DIR/malformed-attrs.rs:117:23: 117:25}`
 
-error: aborting due to 74 previous errors; 8 warnings emitted
+error: aborting due to 75 previous errors; 8 warnings emitted
 
 Some errors have detailed explanations: E0308, E0463, E0539, E0565, E0658, E0805.
 For more information about an error, try `rustc --explain E0308`.
@@ -1010,9 +1020,20 @@ LL | #[ignore()]
    = note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
    = note: `#[deny(ill_formed_attribute_input)]` (part of `#[deny(future_incompatible)]`) on by default
 
+Future breakage diagnostic:
+error: use of deprecated `no_link` attribute
+  --> $DIR/malformed-attrs.rs:208:1
+   |
+LL | #[no_link()]
+   | ^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
+   = note: `#[deny(no_link_attributes)]` (part of `#[deny(future_incompatible)]`) on by default
+
 Future breakage diagnostic:
 error: valid forms for the attribute are `ignore` and `ignore = "reason"`
-  --> $DIR/malformed-attrs.rs:224:3
+  --> $DIR/malformed-attrs.rs:226:3
    |
 LL | #[ignore = 1]
    |   ^^^^^^^^^^

tests/ui/attributes/no_link/auxiliary/no_link-crate.rs

@@ -1,6 +1,7 @@
 //@ no-prefer-dynamic
 
 #![crate_type = "rlib"]
+#![warn(no_link_attributes)]
 
 #[macro_use] #[no_link] extern crate empty_crate_1 as t1;
 #[macro_use] extern crate empty_crate_2 as t2;

tests/ui/attributes/no_link/no-link-struct.rs

@@ -1,7 +1,11 @@
 //@ check-pass
 //@ aux-build:empty-struct.rs
 
+#![warn(no_link_attributes)]
+
 #[no_link]
+//~^ WARN use of deprecated `no_link` attribute
+//~| WARN this was previously accepted by the compiler
 extern crate empty_struct;
 
 fn main() {

tests/ui/attributes/no_link/no-link-struct.stderr

@@ -0,0 +1,31 @@
+warning: use of deprecated `no_link` attribute
+  --> $DIR/no-link-struct.rs:6:1
+   |
+LL | #[no_link]
+   | ^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
+note: the lint level is defined here
+  --> $DIR/no-link-struct.rs:4:9
+   |
+LL | #![warn(no_link_attributes)]
+   |         ^^^^^^^^^^^^^^^^^^
+
+warning: 1 warning emitted
+
+Future incompatibility report: Future breakage diagnostic:
+warning: use of deprecated `no_link` attribute
+  --> $DIR/no-link-struct.rs:6:1
+   |
+LL | #[no_link]
+   | ^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
+note: the lint level is defined here
+  --> $DIR/no-link-struct.rs:4:9
+   |
+LL | #![warn(no_link_attributes)]
+   |         ^^^^^^^^^^^^^^^^^^
+

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

@@ -29,6 +29,10 @@
 //~| WARN previously accepted
 #![no_link]
 //~^ ERROR: the `no_link` attribute cannot be used on crates
+//~| ERROR use of deprecated `no_link` attribute
+//~| WARN this was previously accepted by the compiler
+//~| NOTE `#[deny(no_link_attributes)]` (part of `#[deny(future_incompatible)]`) on by default
+//~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
 #![export_name = "2200"]
 //~^ ERROR: attribute cannot be used on
 //~| NOTE takes precedence
@@ -58,38 +62,65 @@ mod inline {
 
 #[no_link]
 //~^ ERROR the `no_link` attribute cannot be used on modules
+//~| ERROR use of deprecated `no_link` attribute
+//~| WARN this was previously accepted by the compiler
+//~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
 mod no_link {
     mod inner { #![no_link] }
     //~^ ERROR the `no_link` attribute cannot be used on modules
+    //~| ERROR use of deprecated `no_link` attribute
+    //~| WARN this was previously accepted by the compiler
+    //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
 
     #[no_link] fn f() {
         //~^ ERROR the `no_link` attribute cannot be used on functions
+        //~| ERROR use of deprecated `no_link` attribute
+        //~| WARN this was previously accepted by the compiler
+        //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
         match () {
             #[no_link]
             //~^ WARN the `no_link` attribute cannot be used on match arms [unused_attributes]
             //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+            //~| ERROR use of deprecated `no_link` attribute
+            //~| WARN this was previously accepted by the compiler
+            //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
             _ => ()
         }
     }
 
     #[no_link]
     //~^ ERROR the `no_link` attribute cannot be used on structs
+    //~| ERROR use of deprecated `no_link` attribute
+    //~| WARN this was previously accepted by the compiler
+    //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
     struct S {
         #[no_link]
         //~^ WARN the `no_link` attribute cannot be used on struct fields [unused_attributes]
         //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+        //~| ERROR use of deprecated `no_link` attribute
+        //~| WARN this was previously accepted by the compiler
+        //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
         field: ()
     }
 
     #[no_link]type T = S;
     //~^ ERROR the `no_link` attribute cannot be used on type aliases
+    //~| ERROR use of deprecated `no_link` attribute
+    //~| WARN this was previously accepted by the compiler
+    //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
 
     #[no_link] impl S { }
     //~^ ERROR the `no_link` attribute cannot be used on inherent impl blocks
+    //~| ERROR use of deprecated `no_link` attribute
+    //~| WARN this was previously accepted by the compiler
+    //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
 
     #[no_link]
     //~^ WARN the `no_link` attribute cannot be used on macro defs
     //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| ERROR use of deprecated `no_link` attribute
+    //~| WARN this was previously accepted by the compiler
+    //~| NOTE for more information, see issue #164032 <https://github.com/rust-lang/rust/issues/164032>
     macro_rules! m{() => {}}
 }