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.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/test/ui/nullable-pointer-size.rs b/src/test/ui/nullable-pointer-size.rs
index 63a106f1292..0384553b699 100644
--- a/src/test/ui/nullable-pointer-size.rs
+++ b/src/test/ui/nullable-pointer-size.rs
@@ -31,5 +31,5 @@ macro_rules! check_type {
 pub fn main() {
     check_type!(&'static isize);
     check_type!(Box<isize>);
-    check_type!(extern fn());
+    check_type!(extern "C" fn());
 }