Add initial support to specify Super Traits

Super Traits are simply TraitBounds upon the implict Self TypeParameter,
such that a trait with a super trait bound almost ends up looking like this

  trait A : B { } -> trait A where Self: B { }

6 files changed, 129 insertions, 5 deletions

diff --git a/gcc/rust/typecheck/rust-hir-trait-resolve.h b/gcc/rust/typecheck/rust-hir-trait-resolve.h
index 49aa2fa..b0e2c0d 100644
--- a/gcc/rust/typecheck/rust-hir-trait-resolve.h
+++ b/gcc/rust/typecheck/rust-hir-trait-resolve.h
@@ -113,10 +113,6 @@ private:
 	return tref;
       }
 
-    // Check if there is a super-trait, and apply this bound to the Self
-    // TypeParam
-    // FIXME
-
     TyTy::BaseType *self = nullptr;
     std::vector<TyTy::SubstitutionParamMapping> substitutions;
     for (auto &generic_param : trait_reference->get_generic_params ())
@@ -147,6 +143,38 @@ private:
 
     rust_assert (self != nullptr);
 
+    // Check if there is a super-trait, and apply this bound to the Self
+    // TypeParam
+    std::vector<TyTy::TypeBoundPredicate> specified_bounds;
+
+    // They also inherit themselves as a bound this enables a trait item to
+    // reference other Self::trait_items
+    specified_bounds.push_back (
+      TyTy::TypeBoundPredicate (trait_reference->get_mappings ().get_defid (),
+				trait_reference->get_locus ()));
+
+    if (trait_reference->has_type_param_bounds ())
+      {
+	for (auto &bound : trait_reference->get_type_param_bounds ())
+	  {
+	    if (bound->get_bound_type ()
+		== HIR::TypeParamBound::BoundType::TRAITBOUND)
+	      {
+		HIR::TraitBound *b
+		  = static_cast<HIR::TraitBound *> (bound.get ());
+
+		// FIXME this might be recursive we need a check for that
+
+		TraitReference *trait = resolve_trait_path (b->get_path ());
+		TyTy::TypeBoundPredicate predicate (
+		  trait->get_mappings ().get_defid (), bound->get_locus ());
+
+		specified_bounds.push_back (std::move (predicate));
+	      }
+	  }
+      }
+    self->inherit_bounds (specified_bounds);
+
     std::vector<TraitItemReference> item_refs;
     for (auto &item : trait_reference->get_trait_items ())
       {
diff --git a/gcc/rust/typecheck/rust-tyty.cc b/gcc/rust/typecheck/rust-tyty.cc
index 899ad59..398b531 100644
--- a/gcc/rust/typecheck/rust-tyty.cc
+++ b/gcc/rust/typecheck/rust-tyty.cc
@@ -99,7 +99,14 @@ BaseType::bounds_compatible (const BaseType &other, Location locus) const
 void
 BaseType::inherit_bounds (const BaseType &other)
 {
-  for (auto &bound : other.get_specified_bounds ())
+  inherit_bounds (other.get_specified_bounds ());
+}
+
+void
+BaseType::inherit_bounds (
+  const std::vector<TyTy::TypeBoundPredicate> &specified_bounds)
+{
+  for (auto &bound : specified_bounds)
     {
       add_bound (bound);
     }
diff --git a/gcc/rust/typecheck/rust-tyty.h b/gcc/rust/typecheck/rust-tyty.h
index 7f149a9..867dc37 100644
--- a/gcc/rust/typecheck/rust-tyty.h
+++ b/gcc/rust/typecheck/rust-tyty.h
@@ -257,6 +257,9 @@ public:
 
   void inherit_bounds (const BaseType &other);
 
+  void inherit_bounds (
+    const std::vector<TyTy::TypeBoundPredicate> &specified_bounds);
+
   virtual bool is_unit () const { return false; }
 
   virtual bool is_concrete () const { return true; }
diff --git a/gcc/testsuite/rust/compile/torture/traits16.rs b/gcc/testsuite/rust/compile/torture/traits16.rs
new file mode 100644
index 0000000..afc4a86
--- /dev/null
+++ b/gcc/testsuite/rust/compile/torture/traits16.rs
@@ -0,0 +1,20 @@
+trait A {
+    fn a() -> i32 {
+        123
+    }
+
+    fn b() -> i32 {
+        Self::a() + 456
+    }
+}
+
+struct S;
+impl A for S {}
+
+fn main() {
+    let a;
+    a = S::a();
+
+    let b;
+    b = S::b();
+}
diff --git a/gcc/testsuite/rust/compile/torture/traits17.rs b/gcc/testsuite/rust/compile/torture/traits17.rs
new file mode 100644
index 0000000..6da8bcb
--- /dev/null
+++ b/gcc/testsuite/rust/compile/torture/traits17.rs
@@ -0,0 +1,23 @@
+trait A {
+    fn a() -> i32 {
+        123
+    }
+}
+
+trait B: A {
+    fn b() -> i32 {
+        Self::a() + 456
+    }
+}
+
+struct S;
+impl A for S {}
+impl B for S {}
+
+fn main() {
+    let a;
+    a = S::a();
+
+    let b;
+    b = S::b();
+}
diff --git a/gcc/testsuite/rust/execute/torture/trait3.rs b/gcc/testsuite/rust/execute/torture/trait3.rs
new file mode 100644
index 0000000..accfa9d
--- /dev/null
+++ b/gcc/testsuite/rust/execute/torture/trait3.rs
@@ -0,0 +1,43 @@
+/* { dg-output "123, 777" } */
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+trait A {
+    fn a() -> i32 {
+        123
+    }
+}
+
+trait B: A {
+    fn b() -> i32 {
+        <T as A>::a() + 456
+    }
+}
+
+struct T;
+// { dg-warning "struct is never constructed" "" { target *-*-* } .-1 }
+
+impl A for T {
+    fn a() -> i32 {
+        321
+    }
+}
+
+struct S;
+impl A for S {}
+impl B for S {}
+
+fn main() -> i32 {
+    let aa = S::a();
+    let bb = S::b();
+
+    unsafe {
+        let a = "%i, %i\n\0";
+        let b = a as *const str;
+        let c = b as *const i8;
+
+        printf(c, aa, bb);
+    }
+    0
+}