Make missing_abi lint warn-by-default.

compiler/rustc_codegen_gcc/example/mini_core.rs

@@ -681,7 +681,7 @@ impl<T> Index<usize> for [T] {
     }
 }
 
-extern {
+extern "C" {
     type VaListImpl;
 }
 

compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs

@@ -258,13 +258,13 @@ fn main() {
 
     assert_eq!(((|()| 42u8) as fn(()) -> u8)(()), 42);
 
-    extern {
+    extern "C" {
         #[linkage = "weak"]
         static ABC: *const u8;
     }
 
     {
-        extern {
+        extern "C" {
             #[linkage = "weak"]
             static ABC: *const u8;
         }

compiler/rustc_codegen_gcc/example/mod_bench.rs

@@ -3,7 +3,7 @@
 #![allow(internal_features)]
 
 #[link(name = "c")]
-extern {}
+extern "C" {}
 
 #[panic_handler]
 fn panic_handler(_: &core::panic::PanicInfo<'_>) -> ! {

compiler/rustc_codegen_gcc/example/std_example.rs

@@ -7,7 +7,7 @@ use std::arch::x86_64::*;
 use std::io::Write;
 use std::ops::Coroutine;
 
-extern {
+extern "C" {
     pub fn printf(format: *const i8, ...) -> i32;
 }
 

compiler/rustc_lint_defs/src/builtin.rs

@@ -3595,7 +3595,7 @@ declare_lint! {
     ///
     /// [Other ABIs]: https://doc.rust-lang.org/reference/items/external-blocks.html#abi
     pub MISSING_ABI,
-    Allow,
+    Warn,
     "No declared ABI for extern declaration"
 }
 

src/tools/clippy/tests/ui/boxed_local.rs

@@ -173,6 +173,7 @@ mod issue_3739 {
 /// This shouldn't warn for `boxed_local` as it is intended to called from non-Rust code.
 pub extern "C" fn do_not_warn_me(_c_pointer: Box<String>) -> () {}
 
+#[allow(missing_abi)]
 #[rustfmt::skip] // Forces rustfmt to not add ABI
 pub extern fn do_not_warn_me_no_abi(_c_pointer: Box<String>) -> () {}
 

src/tools/clippy/tests/ui/boxed_local.stderr

@@ -14,13 +14,13 @@ LL | pub fn new(_needs_name: Box<PeekableSeekable<&()>>) -> () {}
    |            ^^^^^^^^^^^
 
 error: local variable doesn't need to be boxed here
-  --> tests/ui/boxed_local.rs:188:44
+  --> tests/ui/boxed_local.rs:189:44
    |
 LL |         fn default_impl_x(self: Box<Self>, x: Box<u32>) -> u32 {
    |                                            ^
 
 error: local variable doesn't need to be boxed here
-  --> tests/ui/boxed_local.rs:196:16
+  --> tests/ui/boxed_local.rs:197:16
    |
 LL |         fn foo(x: Box<u32>) {}
    |                ^

src/tools/clippy/tests/ui/doc/doc-fixable.fixed

@@ -240,7 +240,7 @@ fn parenthesized_word() {}
 /// UXes
 fn plural_acronym_test() {}
 
-extern {
+extern "C" {
     /// `foo()`
     fn in_extern();
 }

src/tools/clippy/tests/ui/doc/doc-fixable.rs

@@ -240,7 +240,7 @@ fn parenthesized_word() {}
 /// UXes
 fn plural_acronym_test() {}
 
-extern {
+extern "C" {
     /// foo()
     fn in_extern();
 }

src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed

@@ -149,6 +149,7 @@ mod msrv {
         //~^ ERROR: this could be a `const fn`
 
         #[rustfmt::skip]
+        #[allow(missing_abi)]
         const extern fn implicit_c() {}
         //~^ ERROR: this could be a `const fn`
 

src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs

@@ -149,6 +149,7 @@ mod msrv {
         //~^ ERROR: this could be a `const fn`
 
         #[rustfmt::skip]
+        #[allow(missing_abi)]
         extern fn implicit_c() {}
         //~^ ERROR: this could be a `const fn`
 

src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.stderr

@@ -222,7 +222,7 @@ LL |         const extern "C" fn c() {}
    |         +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:152:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:153:9
    |
 LL |         extern fn implicit_c() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -233,7 +233,7 @@ LL |         const extern fn implicit_c() {}
    |         +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:169:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:170:9
    |
 LL | /         pub fn new(strings: Vec<String>) -> Self {
 LL | |             Self { strings }
@@ -246,7 +246,7 @@ LL |         pub const fn new(strings: Vec<String>) -> Self {
    |             +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:174:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:175:9
    |
 LL | /         pub fn empty() -> Self {
 LL | |             Self { strings: Vec::new() }
@@ -259,7 +259,7 @@ LL |         pub const fn empty() -> Self {
    |             +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:185:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:186:9
    |
 LL | /         pub fn new(text: String) -> Self {
 LL | |             let vec = Vec::new();
@@ -273,7 +273,7 @@ LL |         pub const fn new(text: String) -> Self {
    |             +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:204:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:205:5
    |
 LL |     fn alias_ty_is_projection(bar: <() as FooTrait>::Foo) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -284,7 +284,7 @@ LL |     const fn alias_ty_is_projection(bar: <() as FooTrait>::Foo) {}
    |     +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:208:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:209:5
    |
 LL |     extern "C-unwind" fn c_unwind() {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -295,7 +295,7 @@ LL |     const extern "C-unwind" fn c_unwind() {}
    |     +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:210:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:211:5
    |
 LL |     extern "system" fn system() {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -306,7 +306,7 @@ LL |     const extern "system" fn system() {}
    |     +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:212:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:213:5
    |
 LL |     extern "system-unwind" fn system_unwind() {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/ui/associated-types/issue-91231.rs

@@ -3,7 +3,7 @@
 #![feature(extern_types)]
 #![allow(dead_code)]
 
-extern {
+extern "C" {
     type Extern;
 }
 

tests/ui/attributes/key-value-expansion.rs

@@ -39,7 +39,7 @@ bug!();
 macro_rules! doc_comment {
     ($x:expr) => {
         #[doc = $x]
-        extern {}
+        extern "C" {}
     };
 }
 

tests/ui/borrowck/issue-92157.rs

@@ -5,7 +5,7 @@
 
 #[cfg(target_os = "linux")]
 #[link(name = "c")]
-extern {}
+extern "C" {}
 
 #[lang = "start"]
 fn start<T>(_main: fn() -> T, _argc: isize, _argv: *const *const u8) -> isize {

tests/ui/coherence/coherence-negative-impls-copy.rs

@@ -18,7 +18,7 @@ impl !Copy for WithDrop {}
 
 struct Type;
 trait Trait {}
-extern {
+extern "C" {
     type ExternType;
 }
 

tests/ui/conditional-compilation/cfg_accessible-not_sure.rs

@@ -63,7 +63,7 @@ const B: bool = true;
 
 // ForeignType::unresolved - error
 
-extern {
+extern "C" {
     type ForeignType;
 }
 

tests/ui/consts/const-eval/validation-ice-extern-type-field.rs

@@ -1,6 +1,6 @@
 #![feature(extern_types)]
 
-extern {
+extern "C" {
     type Opaque;
 }
 

tests/ui/delegation/glob-non-impl.rs

@@ -11,7 +11,7 @@ trait OtherTrait {
     reuse Trait::*; //~ ERROR glob delegation is only supported in impls
 }
 
-extern {
+extern "C" {
     reuse Trait::*; //~ ERROR delegation is not supported in `extern` blocks
 }
 

tests/ui/extern/extern-type-diag-not-similar.rs

@@ -4,11 +4,11 @@
 // because they are both extern types.
 
 #![feature(extern_types)]
-extern {
+extern "C" {
     type ShouldNotBeMentioned;
 }
 
-extern {
+extern "C" {
     type Foo;
 }
 

tests/ui/extern/issue-10025.rs

@@ -1,5 +1,5 @@
 //@ run-pass
-#![allow(dead_code)]
+#![allow(dead_code, missing_abi)]
 
 unsafe extern fn foo() {}
 unsafe extern "C" fn bar() {}

tests/ui/extern/issue-95829.rs

@@ -1,6 +1,6 @@
 //@ edition:2018
 
-extern {
+extern "C" {
     async fn L() { //~ ERROR: incorrect function inside `extern` block
         //~^ ERROR: functions in `extern` blocks cannot have `async` qualifier
         async fn M() {}

tests/ui/extern/issue-95829.stderr

@@ -1,8 +1,8 @@
 error: incorrect function inside `extern` block
   --> $DIR/issue-95829.rs:4:14
    |
-LL |   extern {
-   |   ------ `extern` blocks define existing foreign functions and functions inside of them cannot have a body
+LL |   extern "C" {
+   |   ---------- `extern` blocks define existing foreign functions and functions inside of them cannot have a body
 LL |       async fn L() {
    |  ______________^___-
    | |              |
@@ -18,8 +18,8 @@ LL | |     }
 error: functions in `extern` blocks cannot have `async` qualifier
   --> $DIR/issue-95829.rs:4:5
    |
-LL | extern {
-   | ------ in this `extern` block
+LL | extern "C" {
+   | ---------- in this `extern` block
 LL |     async fn L() {
    |     ^^^^^ help: remove the `async` qualifier
 

tests/ui/extern/not-in-block.rs

@@ -1,4 +1,5 @@
 #![crate_type = "lib"]
+#![allow(missing_abi)]
 
 extern fn none_fn(x: bool) -> i32;
 //~^ ERROR free function without a body

tests/ui/extern/not-in-block.stderr

@@ -1,5 +1,5 @@
 error: free function without a body
-  --> $DIR/not-in-block.rs:3:1
+  --> $DIR/not-in-block.rs:4:1
    |
 LL | extern fn none_fn(x: bool) -> i32;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -14,7 +14,7 @@ LL | extern { fn none_fn(x: bool) -> i32; }
    | ~~~~~~~~                             +
 
 error: free function without a body
-  --> $DIR/not-in-block.rs:5:1
+  --> $DIR/not-in-block.rs:6:1
    |
 LL | extern "C" fn c_fn(x: bool) -> i32;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/ui/foreign/issue-91370-foreign-fn-block-impl.rs

@@ -1,6 +1,6 @@
 // Regression test for issue #91370.
 
-extern {
+extern "C" {
     //~^ `extern` blocks define existing foreign functions
     fn f() {
         //~^ incorrect function inside `extern` block

tests/ui/foreign/issue-91370-foreign-fn-block-impl.stderr

@@ -1,8 +1,8 @@
 error: incorrect function inside `extern` block
   --> $DIR/issue-91370-foreign-fn-block-impl.rs:5:8
    |
-LL |   extern {
-   |   ------ `extern` blocks define existing foreign functions and functions inside of them cannot have a body
+LL |   extern "C" {
+   |   ---------- `extern` blocks define existing foreign functions and functions inside of them cannot have a body
 LL |
 LL |       fn f() {
    |  ________^___-

tests/ui/invalid/invalid-rustc_legacy_const_generics-arguments.rs

@@ -21,7 +21,7 @@ struct S;
 #[rustc_legacy_const_generics(0usize)] //~ ERROR suffixed literals are not allowed in attributes
 fn foo6<const X: usize>() {}
 
-extern {
+extern "C" {
     #[rustc_legacy_const_generics(1)] //~ ERROR attribute should be applied to a function
     fn foo7<const X: usize>(); //~ ERROR foreign items may not have const parameters
 }

tests/ui/link-native-libs/issue-109144.rs

@@ -1,4 +1,4 @@
 #![crate_type = "lib"]
 #[link(kind = "static", modifiers = "+whole-archive,+bundle")]
 //~^ ERROR `#[link]` attribute requires a `name = "string"` argument
-extern  {}
+extern "C" {}

tests/ui/link-native-libs/suggest-libname-only-1.stderr

@@ -1,6 +1,14 @@
+warning: extern declarations without an explicit ABI are deprecated
+  --> $DIR/suggest-libname-only-1.rs:7:1
+   |
+LL | extern { }
+   | ^^^^^^ help: explicitly specify the C ABI: `extern "C"`
+   |
+   = note: `#[warn(missing_abi)]` on by default
+
 error: could not find native static library `libfoo.a`, perhaps an -L flag is missing?
    |
    = help: only provide the library name `foo`, not the full filename
 
-error: aborting due to 1 previous error
+error: aborting due to 1 previous error; 1 warning emitted
 

tests/ui/link-native-libs/suggest-libname-only-2.stderr

@@ -1,6 +1,14 @@
+warning: extern declarations without an explicit ABI are deprecated
+  --> $DIR/suggest-libname-only-2.rs:7:1
+   |
+LL | extern { }
+   | ^^^^^^ help: explicitly specify the C ABI: `extern "C"`
+   |
+   = note: `#[warn(missing_abi)]` on by default
+
 error: could not find native static library `bar.lib`, perhaps an -L flag is missing?
    |
    = help: only provide the library name `bar`, not the full filename
 
-error: aborting due to 1 previous error
+error: aborting due to 1 previous error; 1 warning emitted
 

tests/ui/lint/function-item-references.rs

@@ -11,7 +11,7 @@ fn baz(x: u32, y: u32) -> u32 { x + y }
 unsafe fn unsafe_fn() { }
 extern "C" fn c_fn() { }
 unsafe extern "C" fn unsafe_c_fn() { }
-unsafe extern fn variadic(_x: u32, _args: ...) { }
+unsafe extern "C" fn variadic(_x: u32, _args: ...) { }
 fn take_generic_ref<'a, T>(_x: &'a T) { }
 fn take_generic_array<T, const N: usize>(_x: [T; N]) { }
 fn multiple_generic<T, U>(_x: T, _y: U) { }