[gcc/devel/rust/master] Support looking up super traits for trait items

[Thomas Schwinge <tschwinge@gcc.gnu.org>]

https://gcc.gnu.org/g:a7d2643d9b09af9f5c5c670626becaa0c0fc1481

commit a7d2643d9b09af9f5c5c670626becaa0c0fc1481
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Wed Oct 5 17:24:42 2022 +0100

    Support looking up super traits for trait items
    
    When supporting calls to super traits we need to allow lookups based on
    the super traits as specified on the TraitReferences.
    
    Fixes #1555

Diff:
---
 gcc/rust/typecheck/rust-hir-trait-ref.h          | 19 ++++++++++
 gcc/testsuite/rust/compile/torture/issue-1555.rs | 48 ++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/gcc/rust/typecheck/rust-hir-trait-ref.h b/gcc/rust/typecheck/rust-hir-trait-ref.h
index 6eec461e8a5..0f4883d6ba3 100644
--- a/gcc/rust/typecheck/rust-hir-trait-ref.h
+++ b/gcc/rust/typecheck/rust-hir-trait-ref.h
@@ -336,6 +336,15 @@ public:
 	    return true;
 	  }
       }
+
+    // lookup super traits
+    for (const auto &super_trait : super_traits)
+      {
+	bool found = super_trait->lookup_trait_item (ident, ref);
+	if (found)
+	  return true;
+      }
+
     return false;
   }
 
@@ -351,6 +360,16 @@ public:
 	if (ident.compare (item.get_identifier ()) == 0)
 	  return &item;
       }
+
+    // lookup super traits
+    for (const auto &super_trait : super_traits)
+      {
+	const TraitItemReference *res
+	  = super_trait->lookup_trait_item (ident, type);
+	if (!res->is_error ())
+	  return res;
+      }
+
     return &TraitItemReference::error_node ();
   }
 
diff --git a/gcc/testsuite/rust/compile/torture/issue-1555.rs b/gcc/testsuite/rust/compile/torture/issue-1555.rs
new file mode 100644
index 00000000000..adb48911648
--- /dev/null
+++ b/gcc/testsuite/rust/compile/torture/issue-1555.rs
@@ -0,0 +1,48 @@
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+struct Foo(i32);
+trait Bar {
+    fn baz(&self);
+}
+
+trait Baz: Bar {
+    fn qux(&self);
+}
+
+impl Bar for Foo {
+    fn baz(&self) {
+        unsafe {
+            let a = "baz %i\n\0";
+            let b = a as *const str;
+            let c = b as *const i8;
+
+            printf(c, self.0);
+        }
+    }
+}
+
+impl Baz for Foo {
+    fn qux(&self) {
+        unsafe {
+            let a = "qux %i\n\0";
+            let b = a as *const str;
+            let c = b as *const i8;
+
+            printf(c, self.0);
+        }
+    }
+}
+
+fn static_dispatch<T: Baz>(t: &T) {
+    t.baz();
+    t.qux();
+}
+
+pub fn main() {
+    let a;
+    a = &Foo(123);
+
+    static_dispatch(a);
+}