Auto merge of #62603 - cuviper:no-unwind-abort, r=joshtriplett

Permit unwinding through FFI by default

This repeats #62505 for master (Rust 1.38+), as #58794 is not yet resolved. This is a stopgap until a stable alternative is available, like [RFC 2699](https://github.com/rust-lang/rfcs/pull/2699), as long as progress is being made to that end.

r? @joshtriplett

src/librustc_mir/build/mod.rs

@@ -502,7 +502,7 @@ fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: DefId, abi: Abi) -> bool {
     // This is a special case: some functions have a C abi but are meant to
     // unwind anyway. Don't stop them.
     match unwind_attr {
-        None => true,
+        None => false, // FIXME(#58794)
         Some(UnwindAttr::Allowed) => false,
         Some(UnwindAttr::Aborts) => true,
     }

src/test/codegen/c-variadic.rs

@@ -2,6 +2,7 @@
 
 #![crate_type = "lib"]
 #![feature(c_variadic)]
+#![feature(unwind_attributes)]
 #![no_std]
 use core::ffi::VaList;
 
@@ -10,6 +11,7 @@ extern "C" {
     fn foreign_c_variadic_1(_: VaList, ...);
 }
 
+#[unwind(aborts)] // FIXME(#58794)
 pub unsafe extern "C" fn use_foreign_c_variadic_0() {
     // Ensure that we correctly call foreign C-variadic functions.
     // CHECK: invoke void (i32, ...) @foreign_c_variadic_0(i32 0)
@@ -24,20 +26,24 @@ pub unsafe extern "C" fn use_foreign_c_variadic_0() {
 
 // Ensure that we do not remove the `va_list` passed to the foreign function when
 // removing the "spoofed" `VaListImpl` that is used by Rust defined C-variadics.
+#[unwind(aborts)] // FIXME(#58794)
 pub unsafe extern "C" fn use_foreign_c_variadic_1_0(ap: VaList) {
     // CHECK: invoke void ({{.*}}*, ...) @foreign_c_variadic_1({{.*}} %ap)
     foreign_c_variadic_1(ap);
 }
 
+#[unwind(aborts)] // FIXME(#58794)
 pub unsafe extern "C" fn use_foreign_c_variadic_1_1(ap: VaList) {
     // CHECK: invoke void ({{.*}}*, ...) @foreign_c_variadic_1({{.*}} %ap, i32 42)
     foreign_c_variadic_1(ap, 42i32);
 }
+#[unwind(aborts)] // FIXME(#58794)
 pub unsafe extern "C" fn use_foreign_c_variadic_1_2(ap: VaList) {
     // CHECK: invoke void ({{.*}}*, ...) @foreign_c_variadic_1({{.*}} %ap, i32 2, i32 42)
     foreign_c_variadic_1(ap, 2i32, 42i32);
 }
 
+#[unwind(aborts)] // FIXME(#58794)
 pub unsafe extern "C" fn use_foreign_c_variadic_1_3(ap: VaList) {
     // CHECK: invoke void ({{.*}}*, ...) @foreign_c_variadic_1({{.*}} %ap, i32 2, i32 42, i32 0)
     foreign_c_variadic_1(ap, 2i32, 42i32, 0i32);

src/test/incremental/hashes/function_interfaces.rs

@@ -94,7 +94,7 @@ pub unsafe fn make_unsafe() {}
 pub fn make_extern() {}
 
 #[cfg(not(cfail1))]
-#[rustc_clean(cfg = "cfail2", except = "Hir, HirBody, mir_built, typeck_tables_of, fn_sig")]
+#[rustc_clean(cfg = "cfail2", except = "Hir, HirBody, typeck_tables_of, fn_sig")]
 #[rustc_clean(cfg = "cfail3")]
 pub extern "C" fn make_extern() {}
 

src/test/incremental/hashes/inherent_impls.rs

@@ -263,7 +263,7 @@ impl Foo {
 #[rustc_clean(cfg="cfail2")]
 #[rustc_clean(cfg="cfail3")]
 impl Foo {
-    #[rustc_clean(cfg="cfail2", except="Hir,HirBody,mir_built,fn_sig,typeck_tables_of")]
+    #[rustc_clean(cfg="cfail2", except="Hir,HirBody,fn_sig,typeck_tables_of")]
     #[rustc_clean(cfg="cfail3")]
     pub extern fn make_method_extern(&self) { }
 }

src/test/ui/abi/abort-on-c-abi.rs

@@ -1,6 +1,7 @@
 // run-pass
 
 #![allow(unused_must_use)]
+#![feature(unwind_attributes)]
 // Since we mark some ABIs as "nounwind" to LLVM, we must make sure that
 // we never unwind through them.
 
@@ -13,6 +14,7 @@ use std::io::prelude::*;
 use std::io;
 use std::process::{Command, Stdio};
 
+#[unwind(aborts)] // FIXME(#58794)
 extern "C" fn panic_in_ffi() {
     panic!("Test");
 }