Auto merge of #76219 - Mark-Simulacrum:extern-require-abi, r=estebank

Add allow-by-default lint on implicit ABI in extern function pointers and items

This adds a new lint, missing_abi, which lints on omitted ABIs on extern blocks, function declarations, and function pointers.

It is currently not emitting the best possible diagnostics -- we need to track the span of "extern" at least or do some heuristic searching based on the available spans -- but seems good enough for an initial pass than can be expanded in future PRs.

This is a pretty large PR, but mostly due to updating a large number of tests to include ABIs; I can split that into a separate PR if it would be helpful, but test updates are already in dedicated commits.

3 files changed, 7 insertions, 5 deletions

diff --git a/src/test/incremental/foreign.rs b/src/test/incremental/foreign.rs
index 498bf892250..f46f92eb500 100644
--- a/src/test/incremental/foreign.rs
+++ b/src/test/incremental/foreign.rs
@@ -13,7 +13,7 @@ use std::ffi::CString;
 mod mlibc {
     use libc::{c_char, c_long, c_longlong};
 
-    extern {
+    extern "C" {
         pub fn atol(x: *const c_char) -> c_long;
         pub fn atoll(x: *const c_char) -> c_longlong;
     }
@@ -31,6 +31,8 @@ fn atoll(s: String) -> i64 {
 
 pub fn main() {
     assert_eq!(atol("1024".to_string()) * 10, atol("10240".to_string()));
-    assert_eq!((atoll("11111111111111111".to_string()) * 10),
-             atoll("111111111111111110".to_string()));
+    assert_eq!(
+        (atoll("11111111111111111".to_string()) * 10),
+        atoll("111111111111111110".to_string())
+    );
 }
diff --git a/src/test/incremental/hashes/inherent_impls.rs b/src/test/incremental/hashes/inherent_impls.rs
index fcd12ad30eb..2e98abae58b 100644
--- a/src/test/incremental/hashes/inherent_impls.rs
+++ b/src/test/incremental/hashes/inherent_impls.rs
@@ -271,7 +271,7 @@ impl Foo {
 impl Foo {
     #[rustc_clean(cfg="cfail2", except="hir_owner,hir_owner_nodes,fn_sig,typeck")]
     #[rustc_clean(cfg="cfail3")]
-    pub extern fn make_method_extern(&self) { }
+    pub extern "C" fn make_method_extern(&self) { }
 }
 
 
diff --git a/src/test/incremental/hashes/trait_defs.rs b/src/test/incremental/hashes/trait_defs.rs
index aa39ea88e0e..4dab032e47f 100644
--- a/src/test/incremental/hashes/trait_defs.rs
+++ b/src/test/incremental/hashes/trait_defs.rs
@@ -312,7 +312,7 @@ trait TraitAddExternModifier {
 trait TraitAddExternModifier {
     #[rustc_dirty(label="hir_owner", cfg="cfail2")]
     #[rustc_clean(label="hir_owner", cfg="cfail3")]
-    extern fn method();
+    extern "C" fn method();
 }