gccrs: typecheck: Add basic handling for applying auto trait bounds

gcc/rust/ChangeLog:

	* hir/rust-ast-lower-item.cc (ASTLoweringItem::visit): Register auto traits in mappings.
	* util/rust-hir-map.cc (Mappings::insert_auto_trait): New.
	(Mappings::get_auto_traits): New.
	* util/rust-hir-map.h: Declare them.
	* typecheck/rust-tyty-bounds.cc (TypeBoundsProbe::scan): Add auto trait bounds when
	scanning.

gcc/testsuite/ChangeLog:

	* rust/compile/nr2/exclude: Some parts of nr2.0 can't handle auto traits yet.
	* rust/compile/auto_traits3.rs: Removed in favor of...
	* rust/compile/auto_traits2.rs: ...this one.
	* rust/compile/auto_traits4.rs: New test.

4 files changed, 18 insertions, 38 deletions

diff --git a/gcc/testsuite/rust/compile/auto_traits2.rs b/gcc/testsuite/rust/compile/auto_traits2.rs
index 7d0dcc1..382d446 100644
--- a/gcc/testsuite/rust/compile/auto_traits2.rs
+++ b/gcc/testsuite/rust/compile/auto_traits2.rs
@@ -15,12 +15,11 @@ fn foo(a: &(dyn A + Send + Sync)) {
 struct S;
 
 impl A for S {
-    fn a_method(&self) {}
+    fn a_method(&self) {} // { dg-warning "unused name" }
 }
 
 fn main() {
     let s = S;
 
-    foo(&s); // { dg-error "bounds not satisfied" }
-             // { dg-error "mismatched type" "" { target *-*-* } .-1 }
+    foo(&s);
 }
diff --git a/gcc/testsuite/rust/compile/auto_traits3.rs b/gcc/testsuite/rust/compile/auto_traits3.rs
deleted file mode 100644
index 81c39ec..0000000
--- a/gcc/testsuite/rust/compile/auto_traits3.rs
+++ /dev/null
@@ -1,34 +0,0 @@
-#![feature(optin_builtin_traits)]
-
-pub unsafe auto trait Send {}
-#[lang = "sync"]
-pub unsafe auto trait Sync {}
-
-trait A {
-    fn a_method(&self) {}
-}
-
-fn foo(a: &(dyn A + Send + Sync)) {
-    a.a_method();
-}
-
-struct S;
-
-impl A for S {
-    fn a_method(&self) {} // { dg-warning "unused" }
-}
-
-// These should not be necessary because they are both auto traits
-// They need to be removed once we figure out the proper implementation for each of them
-// However, it'd be silly to implement other traits in order to ensure the test is okay,
-// as these extra trait bounds are only allowed to use auto traits
-// FIXME: #3327
-// FIXME: #3326
-unsafe impl Send for S {}
-unsafe impl Sync for S {}
-
-fn main() {
-    let s = S;
-
-    foo(&s);
-}
diff --git a/gcc/testsuite/rust/compile/auto_traits4.rs b/gcc/testsuite/rust/compile/auto_traits4.rs
new file mode 100644
index 0000000..f1cd1e4
--- /dev/null
+++ b/gcc/testsuite/rust/compile/auto_traits4.rs
@@ -0,0 +1,14 @@
+#![feature(optin_builtin_traits)]
+
+unsafe auto trait Send {}
+unsafe auto trait Sync {}
+
+fn take_send(_: &dyn Send) {}
+fn take_sync(_: &dyn Sync) {}
+
+fn main() {
+    let a = i32;
+
+    take_send(&a);
+    take_sync(&a);
+}
diff --git a/gcc/testsuite/rust/compile/nr2/exclude b/gcc/testsuite/rust/compile/nr2/exclude
index 60322f3..a8e3ba5 100644
--- a/gcc/testsuite/rust/compile/nr2/exclude
+++ b/gcc/testsuite/rust/compile/nr2/exclude
@@ -140,7 +140,8 @@ issue-2907.rs
 issue-2423.rs
 issue-266.rs
 additional-trait-bounds2.rs
-auto_traits3.rs
+auto_traits2.rs
+auto_traits4.rs
 issue-3140.rs
 cmp1.rs
 derive_clone_enum1.rs