Rollup merge of #144356 - GuillaumeGomez:gcc-ignore-tests, r=jieyouxu

Add `ignore-backends` annotations in failing GCC backend ui tests

Follow-up of #144125.

In the GCC backend, we don't support all ui tests yet and we have a list of tests we currently ignore available [here](https://github.com/rust-lang/rustc_codegen_gcc/blob/master/tests/failing-ui-tests.txt).

This PR adds the `ignore-backends` annotations to the corresponding ui tests.

The second commit is a fix to compiletest, complaining about `ignore-backends`.

r? ```@jieyouxu```

Author: tgross35

src/tools/compiletest/src/directives/cfg.rs

@@ -285,6 +285,11 @@ fn parse_cfg_name_directive<'a>(
         if name == "gdb-version" {
             outcome = MatchOutcome::External;
         }
+
+        // Don't error out for ignore-backends,as it is handled elsewhere.
+        if name == "backends" {
+            outcome = MatchOutcome::External;
+        }
     }
 
     ParsedNameDirective {

tests/ui/allocator/no_std-alloc-error-handler-custom.rs

@@ -2,6 +2,7 @@
 //@ ignore-android no libc
 //@ ignore-emscripten no libc
 //@ ignore-sgx no libc
+//@ ignore-backends: gcc
 //@ only-linux
 //@ compile-flags:-C panic=abort
 //@ aux-build:helper.rs

tests/ui/allocator/no_std-alloc-error-handler-default.rs

@@ -2,6 +2,7 @@
 //@ ignore-android no libc
 //@ ignore-emscripten no libc
 //@ ignore-sgx no libc
+//@ ignore-backends: gcc
 //@ only-linux
 //@ compile-flags:-C panic=abort
 //@ aux-build:helper.rs

tests/ui/asm/may_unwind.rs

@@ -1,6 +1,7 @@
 //@ run-pass
 //@ needs-asm-support
 //@ needs-unwind
+//@ ignore-backends: gcc
 
 #![feature(asm_unwind)]
 

tests/ui/asm/x86_64/may_unwind.rs

@@ -2,6 +2,7 @@
 //@ run-pass
 //@ needs-asm-support
 //@ needs-unwind
+//@ ignore-backends: gcc
 
 #![feature(asm_unwind)]
 

tests/ui/async-await/deep-futures-are-freeze.rs

@@ -1,3 +1,4 @@
+//@ ignore-backends: gcc
 //@ build-pass
 //@ compile-flags: -Copt-level=s -Clto=fat
 //@ no-prefer-dynamic

tests/ui/async-await/in-trait/dont-project-to-specializable-projection.rs

@@ -1,3 +1,4 @@
+//@ ignore-backends: gcc
 //@ edition: 2021
 //@ known-bug: #108309
 

tests/ui/async-await/in-trait/dont-project-to-specializable-projection.stderr

@@ -1,27 +1,27 @@
 error[E0053]: method `foo` has an incompatible type for trait
-  --> $DIR/dont-project-to-specializable-projection.rs:13:5
+  --> $DIR/dont-project-to-specializable-projection.rs:14:5
    |
 LL |     default async fn foo(_: T) -> &'static str {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected associated type, found future
    |
 note: type in trait
-  --> $DIR/dont-project-to-specializable-projection.rs:9:5
+  --> $DIR/dont-project-to-specializable-projection.rs:10:5
    |
 LL |     async fn foo(_: T) -> &'static str;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: expected signature `fn(_) -> impl Future<Output = &'static str>`
               found signature `fn(_) -> impl Future<Output = &'static str>`
 
 error: async associated function in trait cannot be specialized
-  --> $DIR/dont-project-to-specializable-projection.rs:13:5
+  --> $DIR/dont-project-to-specializable-projection.rs:14:5
    |
 LL |     default async fn foo(_: T) -> &'static str {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: specialization behaves in inconsistent and surprising ways with async functions in traits, and for now is disallowed
 
 error[E0599]: no method named `poll` found for struct `Pin<&mut impl Future<Output = ()>>` in the current scope
-  --> $DIR/dont-project-to-specializable-projection.rs:48:28
+  --> $DIR/dont-project-to-specializable-projection.rs:49:28
    |
 LL |         match fut.as_mut().poll(ctx) {
    |                            ^^^^ method not found in `Pin<&mut impl Future<Output = ()>>`

tests/ui/backtrace/dylib-dep.rs

@@ -8,6 +8,7 @@
 //@ ignore-fuchsia Backtraces not symbolized
 //@ ignore-musl musl doesn't support dynamic libraries (at least when the original test was written).
 //@ needs-unwind
+//@ ignore-backends: gcc
 //@ compile-flags: -g -Copt-level=0 -Cstrip=none -Cforce-frame-pointers=yes
 //@ ignore-emscripten Requires custom symbolization code
 //@ aux-crate: dylib_dep_helper=dylib-dep-helper.rs

tests/ui/cfg/cfg-panic-abort.rs

@@ -1,6 +1,7 @@
 //@ build-pass
 //@ compile-flags: -C panic=abort
 //@ no-prefer-dynamic
+//@ ignore-backends: gcc
 
 #[cfg(panic = "unwind")]
 pub fn bad() -> i32 { }