Rollup merge of #127921 - spastorino:stabilize-unsafe-extern-blocks, …

…r=compiler-errors Stabilize unsafe extern blocks (RFC 3484) # Stabilization report ## Summary This is a tracking issue for the RFC 3484: Unsafe Extern Blocks We are stabilizing `#![feature(unsafe_extern_blocks)]`, as described in [Unsafe Extern Blocks RFC 3484](rust-lang/rfcs#3484). This feature makes explicit that declaring an extern block is unsafe. Starting in Rust 2024, all extern blocks must be marked as unsafe. In all editions, items within unsafe extern blocks may be marked as safe to use. RFC: rust-lang/rfcs#3484 Tracking issue: #123743 ## What is stabilized ### Summary of stabilization We now need extern blocks to be marked as unsafe and items inside can also have safety modifiers (unsafe or safe), by default items with no modifiers are unsafe to offer easy migration without surprising results. ```rust unsafe extern { // sqrt (from libm) may be called with any `f64` pub safe fn sqrt(x: f64) -> f64; // strlen (from libc) requires a valid pointer, // so we mark it as being an unsafe fn pub unsafe fn strlen(p: *const c_char) -> usize; // this function doesn't say safe or unsafe, so it defaults to unsafe pub fn free(p: *mut core::ffi::c_void); pub safe static IMPORTANT_BYTES: [u8; 256]; pub safe static LINES: SyncUnsafeCell<i32>; } ``` ## Tests The relevant tests are in `tests/ui/rust-2024/unsafe-extern-blocks`. ## History - #124482 - #124455 - #125077 - #125522 - #126738 - #126749 - #126755 - #126757 - #126758 - #126756 - #126973 - #127535 - rust-lang/rustfmt#6204 ## Unresolved questions I am not aware of any unresolved questions.
rust-lang · Aug 3, 2024 · 7d9ed2a · 7d9ed2a
2 parents edc4dc3 + 8366c7f
commit 7d9ed2a
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Showing 41 changed files with 85 additions and 163 deletions.
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -453,11 +453,6 @@ impl<'a> AstValidator<'a> {
                             item_span: span,
                             block: Some(self.current_extern_span().shrink_to_lo()),
                         });
-                    } else if !self.features.unsafe_extern_blocks {
-                        self.dcx().emit_err(errors::InvalidSafetyOnExtern {
-                            item_span: span,
-                            block: None,
-                        });
                     }
                 }
             }
@@ -1054,32 +1049,19 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         errors::VisibilityNotPermittedNote::IndividualForeignItems,
                     );
 
-                    if this.features.unsafe_extern_blocks {
-                        if &Safety::Default == safety {
-                            if item.span.at_least_rust_2024() {
-                                this.dcx()
-                                    .emit_err(errors::MissingUnsafeOnExtern { span: item.span });
-                            } else {
-                                this.lint_buffer.buffer_lint(
-                                    MISSING_UNSAFE_ON_EXTERN,
-                                    item.id,
-                                    item.span,
-                                    BuiltinLintDiag::MissingUnsafeOnExtern {
-                                        suggestion: item.span.shrink_to_lo(),
-                                    },
-                                );
-                            }
+                    if &Safety::Default == safety {
+                        if item.span.at_least_rust_2024() {
+                            this.dcx().emit_err(errors::MissingUnsafeOnExtern { span: item.span });
+                        } else {
+                            this.lint_buffer.buffer_lint(
+                                MISSING_UNSAFE_ON_EXTERN,
+                                item.id,
+                                item.span,
+                                BuiltinLintDiag::MissingUnsafeOnExtern {
+                                    suggestion: item.span.shrink_to_lo(),
+                                },
+                            );
                         }
-                    } else if let &Safety::Unsafe(span) = safety {
-                        let mut diag = this
-                            .dcx()
-                            .create_err(errors::UnsafeItem { span, kind: "extern block" });
-                        rustc_session::parse::add_feature_diagnostics(
-                            &mut diag,
-                            self.session,
-                            sym::unsafe_extern_blocks,
-                        );
-                        diag.emit();
                     }
 
                     if abi.is_none() {

diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -560,10 +560,6 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
     gate_all!(precise_capturing, "precise captures on `impl Trait` are experimental");
     gate_all!(global_registration, "global registration is experimental");
     gate_all!(unsafe_attributes, "`#[unsafe()]` markers for attributes are experimental");
-    gate_all!(
-        unsafe_extern_blocks,
-        "`unsafe extern {}` blocks and `safe` keyword are experimental"
-    );
     gate_all!(return_type_notation, "return type notation is experimental");
 
     if !visitor.features.never_patterns {

diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
@@ -390,6 +390,8 @@ declare_features! (
     (accepted, unrestricted_attribute_tokens, "1.34.0", Some(55208)),
     /// The `unsafe_op_in_unsafe_fn` lint (allowed by default): no longer treat an unsafe function as an unsafe block.
     (accepted, unsafe_block_in_unsafe_fn, "1.52.0", Some(71668)),
+    /// Allows unsafe on extern declarations and safety qualifiers over internal items.
+    (accepted, unsafe_extern_blocks, "CURRENT_RUSTC_VERSION", Some(123743)),
     /// Allows importing and reexporting macros with `use`,
     /// enables macro modularization in general.
     (accepted, use_extern_macros, "1.30.0", Some(35896)),

diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
@@ -631,8 +631,6 @@ declare_features! (
     (incomplete, unnamed_fields, "1.74.0", Some(49804)),
     /// Allows unsafe attributes.
     (unstable, unsafe_attributes, "1.80.0", Some(123757)),
-    /// Allows unsafe on extern declarations and safety qualifiers over internal items.
-    (unstable, unsafe_extern_blocks, "1.80.0", Some(123743)),
     /// Allows const generic parameters to be defined with types that
     /// are not `Sized`, e.g. `fn foo<const N: [u8]>() {`.
     (incomplete, unsized_const_params, "CURRENT_RUSTC_VERSION", Some(95174)),

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
@@ -4934,7 +4934,6 @@ declare_lint! {
     /// ### Example
     ///
     /// ```rust
-    /// #![feature(unsafe_extern_blocks)]
     /// #![warn(missing_unsafe_on_extern)]
     /// #![allow(dead_code)]
     ///

diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
@@ -1250,9 +1250,6 @@ impl<'a> Parser<'a> {
         if self.eat_keyword_case(kw::Unsafe, case) {
             Safety::Unsafe(self.prev_token.uninterpolated_span())
         } else if self.eat_keyword_case(kw::Safe, case) {
-            self.psess
-                .gated_spans
-                .gate(sym::unsafe_extern_blocks, self.prev_token.uninterpolated_span());
             Safety::Safe(self.prev_token.uninterpolated_span())
         } else {
             Safety::Default

diff --git a/tests/rustdoc/unsafe-extern-blocks.rs b/tests/rustdoc/unsafe-extern-blocks.rs
@@ -1,6 +1,5 @@
 // Test to ensure the feature is working as expected.
 
-#![feature(unsafe_extern_blocks)]
 #![crate_name = "foo"]
 
 // @has 'foo/index.html'
@@ -13,7 +12,7 @@
 // @count - '//ul[@class="item-table"]//sup[@title="unsafe function"]' 1
 // @has - '//ul[@class="item-table"]//sup[@title="unsafe function"]' '⚠'
 
-unsafe extern {
+unsafe extern "C" {
     // @has 'foo/static.FOO.html'
     // @has - '//pre[@class="rust item-decl"]' 'pub static FOO: i32'
     pub safe static FOO: i32;

diff --git a/tests/ui/feature-gates/feature-gate-unsafe-extern-blocks.rs b/tests/ui/feature-gates/feature-gate-unsafe-extern-blocks.rs
diff --git a/tests/ui/feature-gates/feature-gate-unsafe-extern-blocks.stderr b/tests/ui/feature-gates/feature-gate-unsafe-extern-blocks.stderr
diff --git a/tests/ui/lint/unsafe_code/unsafe-extern-blocks.rs b/tests/ui/lint/unsafe_code/unsafe-extern-blocks.rs
@@ -1,4 +1,3 @@
-#![feature(unsafe_extern_blocks)]
 #![deny(unsafe_code)]
 
 #[allow(unsafe_code)]

diff --git a/tests/ui/lint/unsafe_code/unsafe-extern-blocks.stderr b/tests/ui/lint/unsafe_code/unsafe-extern-blocks.stderr
@@ -1,5 +1,5 @@
 error: usage of an `unsafe extern` block
-  --> $DIR/unsafe-extern-blocks.rs:9:1
+  --> $DIR/unsafe-extern-blocks.rs:8:1
    |
 LL | / unsafe extern "C" {
 LL | |
@@ -8,7 +8,7 @@ LL | | }
    | |_^
    |
 note: the lint level is defined here
-  --> $DIR/unsafe-extern-blocks.rs:2:9
+  --> $DIR/unsafe-extern-blocks.rs:1:9
    |
 LL | #![deny(unsafe_code)]
    |         ^^^^^^^^^^^

diff --git a/tests/ui/parser/unsafe-foreign-mod-2.rs b/tests/ui/parser/unsafe-foreign-mod-2.rs
@@ -1,8 +1,6 @@
 extern "C" unsafe {
     //~^ ERROR expected `{`, found keyword `unsafe`
-    //~| ERROR extern block cannot be declared unsafe
     unsafe fn foo();
-    //~^ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
 }
 
 fn main() {}
diff --git a/tests/ui/parser/unsafe-foreign-mod-2.stderr b/tests/ui/parser/unsafe-foreign-mod-2.stderr
@@ -4,21 +4,5 @@ error: expected `{`, found keyword `unsafe`
 LL | extern "C" unsafe {
    |            ^^^^^^ expected `{`
 
-error: extern block cannot be declared unsafe
-  --> $DIR/unsafe-foreign-mod-2.rs:1:12
-   |
-LL | extern "C" unsafe {
-   |            ^^^^^^
-   |
-   = note: see issue #123743 <https://github.com/rust-lang/rust/issues/123743> for more information
-   = help: add `#![feature(unsafe_extern_blocks)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error: items in unadorned `extern` blocks cannot have safety qualifiers
-  --> $DIR/unsafe-foreign-mod-2.rs:4:5
-   |
-LL |     unsafe fn foo();
-   |     ^^^^^^^^^^^^^^^^
-
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error
 
diff --git a/tests/ui/parser/unsafe-foreign-mod.rs b/tests/ui/parser/unsafe-foreign-mod.rs
@@ -1,5 +1,5 @@
-unsafe extern "C" {
-    //~^ ERROR extern block cannot be declared unsafe
-}
+//@ check-pass
+
+unsafe extern "C" {}
 
 fn main() {}
diff --git a/tests/ui/parser/unsafe-foreign-mod.stderr b/tests/ui/parser/unsafe-foreign-mod.stderr
diff --git a/tests/ui/rust-2024/safe-outside-extern.rs b/tests/ui/rust-2024/safe-outside-extern.rs
@@ -1,29 +1,21 @@
-//@ revisions: gated ungated
-#![cfg_attr(gated, feature(unsafe_extern_blocks))]
-
 safe fn foo() {}
 //~^ ERROR: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
-//[ungated]~| ERROR: unsafe extern {}` blocks and `safe` keyword are experimental [E0658]
 
 safe static FOO: i32 = 1;
 //~^ ERROR: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
-//[ungated]~| ERROR: unsafe extern {}` blocks and `safe` keyword are experimental [E0658]
 
 trait Foo {
     safe fn foo();
     //~^ ERROR: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
-    //[ungated]~| ERROR: unsafe extern {}` blocks and `safe` keyword are experimental [E0658]
 }
 
 impl Foo for () {
     safe fn foo() {}
     //~^ ERROR: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
-    //[ungated]~| ERROR: unsafe extern {}` blocks and `safe` keyword are experimental [E0658]
 }
 
 type FnPtr = safe fn(i32, i32) -> i32;
 //~^ ERROR: function pointers cannot be declared with `safe` safety qualifier
-//[ungated]~| ERROR: unsafe extern {}` blocks and `safe` keyword are experimental [E0658]
 
 unsafe static LOL: u8 = 0;
 //~^ ERROR: static items cannot be declared with `unsafe` safety qualifier outside of `extern` block

diff --git a/tests/ui/rust-2024/safe-outside-extern.stderr b/tests/ui/rust-2024/safe-outside-extern.stderr
@@ -0,0 +1,38 @@
+error: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
+  --> $DIR/safe-outside-extern.rs:1:1
+   |
+LL | safe fn foo() {}
+   | ^^^^^^^^^^^^^^^^
+
+error: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
+  --> $DIR/safe-outside-extern.rs:4:1
+   |
+LL | safe static FOO: i32 = 1;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
+  --> $DIR/safe-outside-extern.rs:8:5
+   |
+LL |     safe fn foo();
+   |     ^^^^^^^^^^^^^^
+
+error: items outside of `unsafe extern { }` cannot be declared with `safe` safety qualifier
+  --> $DIR/safe-outside-extern.rs:13:5
+   |
+LL |     safe fn foo() {}
+   |     ^^^^^^^^^^^^^^^^
+
+error: function pointers cannot be declared with `safe` safety qualifier
+  --> $DIR/safe-outside-extern.rs:17:14
+   |
+LL | type FnPtr = safe fn(i32, i32) -> i32;
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: static items cannot be declared with `unsafe` safety qualifier outside of `extern` block
+  --> $DIR/safe-outside-extern.rs:20:1
+   |
+LL | unsafe static LOL: u8 = 0;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
+
diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.edition2021.stderr b/tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.edition2021.stderr
@@ -1,13 +1,13 @@
 error[E0133]: call to unsafe function `test1` is unsafe and requires unsafe function or block
-  --> $DIR/extern-items-unsafe.rs:14:5
+  --> $DIR/extern-items-unsafe.rs:12:5
    |
 LL |     test1(TEST1);
    |     ^^^^^^^^^^^^ call to unsafe function
    |
    = note: consult the function's documentation for information on how to avoid undefined behavior
 
 error[E0133]: use of extern static is unsafe and requires unsafe function or block
-  --> $DIR/extern-items-unsafe.rs:14:11
+  --> $DIR/extern-items-unsafe.rs:12:11
    |
 LL |     test1(TEST1);
    |           ^^^^^ use of extern static

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.edition2024.stderr b/tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.edition2024.stderr
@@ -1,13 +1,13 @@
 error[E0133]: call to unsafe function `test1` is unsafe and requires unsafe block
-  --> $DIR/extern-items-unsafe.rs:14:5
+  --> $DIR/extern-items-unsafe.rs:12:5
    |
 LL |     test1(TEST1);
    |     ^^^^^^^^^^^^ call to unsafe function
    |
    = note: consult the function's documentation for information on how to avoid undefined behavior
 
 error[E0133]: use of extern static is unsafe and requires unsafe block
-  --> $DIR/extern-items-unsafe.rs:14:11
+  --> $DIR/extern-items-unsafe.rs:12:11
    |
 LL |     test1(TEST1);
    |           ^^^^^ use of extern static

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.rs b/tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.rs
@@ -3,8 +3,6 @@
 //@[edition2024] edition:2024
 //@[edition2024] compile-flags: -Zunstable-options
 
-#![feature(unsafe_extern_blocks)]
-
 unsafe extern "C" {
     static TEST1: i32;
     fn test1(i: i32);

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/extern-items.edition2024.stderr b/tests/ui/rust-2024/unsafe-extern-blocks/extern-items.edition2024.stderr
@@ -1,5 +1,5 @@
 error: extern blocks must be unsafe
-  --> $DIR/extern-items.rs:9:1
+  --> $DIR/extern-items.rs:7:1
    |
 LL | / extern "C" {
 LL | |

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/extern-items.rs b/tests/ui/rust-2024/unsafe-extern-blocks/extern-items.rs
@@ -4,8 +4,6 @@
 //@[edition2024] edition:2024
 //@[edition2024] compile-flags: -Zunstable-options
 
-#![feature(unsafe_extern_blocks)]
-
 extern "C" {
     //[edition2024]~^ ERROR extern blocks must be unsafe
     static TEST1: i32;

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/safe-impl-trait.rs b/tests/ui/rust-2024/unsafe-extern-blocks/safe-impl-trait.rs
@@ -1,6 +1,3 @@
-//@ revisions: gated ungated
-#![cfg_attr(gated, feature(unsafe_extern_blocks))]
-
 trait Bar {}
 safe impl Bar for () { }
 //~^ ERROR expected one of `!` or `::`, found keyword `impl`

diff --git a/...xtern-blocks/safe-impl-trait.gated.stderr → ...safe-extern-blocks/safe-impl-trait.stderr b/...xtern-blocks/safe-impl-trait.gated.stderr → ...safe-extern-blocks/safe-impl-trait.stderr
@@ -1,5 +1,5 @@
 error: expected one of `!` or `::`, found keyword `impl`
-  --> $DIR/safe-impl-trait.rs:5:6
+  --> $DIR/safe-impl-trait.rs:2:6
    |
 LL | safe impl Bar for () { }
    |      ^^^^ expected one of `!` or `::`

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/safe-items.rs b/tests/ui/rust-2024/unsafe-extern-blocks/safe-items.rs
@@ -4,8 +4,6 @@
 //@[edition2024] compile-flags: -Zunstable-options
 //@ check-pass
 
-#![feature(unsafe_extern_blocks)]
-
 unsafe extern "C" {
     safe static TEST1: i32;
     safe fn test1(i: i32);

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/safe-trait.rs b/tests/ui/rust-2024/unsafe-extern-blocks/safe-trait.rs
@@ -1,6 +1,3 @@
-//@ revisions: gated ungated
-#![cfg_attr(gated, feature(unsafe_extern_blocks))]
-
 safe trait Foo {}
 //~^ ERROR expected one of `!` or `::`, found keyword `trait`
 

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/safe-trait.stderr b/tests/ui/rust-2024/unsafe-extern-blocks/safe-trait.stderr
@@ -0,0 +1,8 @@
+error: expected one of `!` or `::`, found keyword `trait`
+  --> $DIR/safe-trait.rs:1:6
+   |
+LL | safe trait Foo {}
+   |      ^^^^^ expected one of `!` or `::`
+
+error: aborting due to 1 previous error
+