Rollup merge of rust-lang#84734 - tmandry:compiletest-needs-unwind, r=Mark-Simulacrum

Add `needs-unwind` and beginning of support for testing `panic=abort` std to compiletest

For the Fuchsia platform we build libstd with `panic=abort` and would like a way to run tests with that enabled. This adds low-level support for this directly to compiletest.

In the future I'd like to add high-level support in rustbuild, e.g. having target-specific flags that allow configuring a panic strategy. (Side note: It would be nice if we could also build multiple configurations for the same target, but I'm getting ahead of myself.)

This plus rust-lang#84500 have everything that's needed to get ui tests passing on fuchsia targets.

Part of rust-lang#84766. Note that this change only includes the header on tests which need an unwinder to _build_, not those which need it to _run_.

r? ```@Mark-Simulacrum```

Author: Dylan-DPC

src/test/ui/cfg/cfg-panic.rs

@@ -1,5 +1,6 @@
 // build-pass
 // compile-flags: -C panic=unwind
+// needs-unwind
 // ignore-emscripten no panic_unwind implementation
 // ignore-wasm32     no panic_unwind implementation
 // ignore-wasm64     no panic_unwind implementation

src/test/ui/intrinsics/intrinsic-alignment.rs

@@ -14,6 +14,7 @@ mod rusti {
           target_os = "dragonfly",
           target_os = "emscripten",
           target_os = "freebsd",
+          target_os = "fuchsia",
           target_os = "linux",
           target_os = "macos",
           target_os = "netbsd",

src/test/ui/issues/issue-70093.rs

@@ -1,6 +1,7 @@
 // run-pass
 // compile-flags: -Zlink-native-libraries=no -Cdefault-linker-libraries=yes
 // ignore-windows - this will probably only work on unixish systems
+// ignore-fuchsia - missing __libc_start_main for some reason (#84733)
 
 #[link(name = "some-random-non-existent-library", kind = "static")]
 extern "C" {}

src/test/ui/panic-handler/weak-lang-item.rs

@@ -1,6 +1,7 @@
 // aux-build:weak-lang-items.rs
 // error-pattern: `#[panic_handler]` function required, but not found
 // error-pattern: language item required, but not found: `eh_personality`
+// needs-unwind since it affects the error output
 // ignore-emscripten compiled with panic=abort, personality not required
 
 #![no_std]

src/test/ui/panic-handler/weak-lang-item.stderr

@@ -1,5 +1,5 @@
 error[E0259]: the name `core` is defined multiple times
-  --> $DIR/weak-lang-item.rs:8:1
+  --> $DIR/weak-lang-item.rs:9:1
    |
 LL | extern crate core;
    | ^^^^^^^^^^^^^^^^^^ `core` reimported here

src/test/ui/panic-runtime/abort-link-to-unwind-dylib.rs

@@ -1,5 +1,6 @@
 // build-fail
 // compile-flags:-C panic=abort -C prefer-dynamic
+// needs-unwind
 // ignore-musl - no dylibs here
 // ignore-emscripten
 // ignore-sgx no dynamic lib support

src/test/ui/panic-runtime/lto-unwind.rs

@@ -2,6 +2,7 @@
 #![allow(unused_variables)]
 
 // compile-flags:-C lto -C panic=unwind
+// needs-unwind
 // no-prefer-dynamic
 // ignore-emscripten no processes
 // ignore-sgx no processes

src/test/ui/panic-runtime/transitive-link-a-bunch.rs

@@ -1,4 +1,5 @@
 // build-fail
+// needs-unwind
 // aux-build:panic-runtime-unwind.rs
 // aux-build:panic-runtime-abort.rs
 // aux-build:wants-panic-runtime-unwind.rs

src/test/ui/panic-runtime/want-unwind-got-abort.rs

@@ -1,4 +1,5 @@
 // build-fail
+// needs-unwind
 // error-pattern:is incompatible with this crate's strategy of `unwind`
 // aux-build:panic-runtime-abort.rs
 // aux-build:panic-runtime-lang-items.rs

src/test/ui/panic-runtime/want-unwind-got-abort2.rs

@@ -1,4 +1,5 @@
 // build-fail
+// needs-unwind
 // error-pattern:is incompatible with this crate's strategy of `unwind`
 // aux-build:panic-runtime-abort.rs
 // aux-build:wants-panic-runtime-abort.rs