Add missing coercion site code to MethodCallExpr's

Arguments to methods are coercion sites and may have implicit conversions
to be performed this adds this missing code for this case.

Fixes #755

2 files changed, 65 insertions, 6 deletions

diff --git a/gcc/rust/backend/rust-compile.cc b/gcc/rust/backend/rust-compile.cc
index f97f701..40e2f86 100644
--- a/gcc/rust/backend/rust-compile.cc
+++ b/gcc/rust/backend/rust-compile.cc
@@ -451,8 +451,6 @@ CompileExpr::visit (HIR::MethodCallExpr &expr)
 	}
     }
 
-  std::vector<Bexpression *> args;
-
   // lookup the autoderef mappings
   std::vector<Resolver::Adjustment> *adjustments = nullptr;
   ok = ctx->get_tyctx ()->lookup_autoderef_mappings (
@@ -478,13 +476,31 @@ CompileExpr::visit (HIR::MethodCallExpr &expr)
 	  break;
 	}
     }
-  args.push_back (self);
+
+  std::vector<Bexpression *> args;
+  args.push_back (self); // adjusted self
 
   // normal args
-  for (auto &argument : expr.get_arguments ())
+  for (size_t i = 0; i < expr.get_arguments ().size (); i++)
     {
-      Bexpression *compiled_expr = CompileExpr::Compile (argument.get (), ctx);
-      args.push_back (compiled_expr);
+      auto &argument = expr.get_arguments ().at (i);
+      auto rvalue = CompileExpr::Compile (argument.get (), ctx);
+
+      // assignments are coercion sites so lets convert the rvalue if
+      // necessary, offset from the already adjusted implicit self
+      bool ok;
+      TyTy::BaseType *expected = fntype->param_at (i + 1).second;
+
+      TyTy::BaseType *actual = nullptr;
+      ok = ctx->get_tyctx ()->lookup_type (
+	argument->get_mappings ().get_hirid (), &actual);
+      rust_assert (ok);
+
+      // coerce it if required
+      rvalue = coercion_site (rvalue, actual, expected, expr.get_locus ());
+
+      // add it to the list
+      args.push_back (rvalue);
     }
 
   auto fncontext = ctx->peek_fn ();
diff --git a/gcc/testsuite/rust/execute/torture/trait10.rs b/gcc/testsuite/rust/execute/torture/trait10.rs
new file mode 100644
index 0000000..615df423
--- /dev/null
+++ b/gcc/testsuite/rust/execute/torture/trait10.rs
@@ -0,0 +1,43 @@
+/* { dg-output "123\n" } */
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+struct Foo(i32);
+trait Bar {
+    fn baz(&self);
+    // { dg-warning "unused name" "" { target *-*-* } .-1 }
+}
+
+impl Bar for Foo {
+    fn baz(&self) {
+        // { dg-warning "unused name" "" { target *-*-* } .-1 }
+        unsafe {
+            let a = "%i\n\0";
+            let b = a as *const str;
+            let c = b as *const i8;
+
+            printf(c, self.0);
+        }
+    }
+}
+
+struct S;
+impl S {
+    fn dynamic_dispatch(self, t: &dyn Bar) {
+        // { dg-warning "unused name" "" { target *-*-* } .-1 }
+        t.baz();
+    }
+}
+
+pub fn main() -> i32 {
+    let a;
+    a = &Foo(123);
+
+    let b;
+    b = S;
+
+    b.dynamic_dispatch(a);
+
+    0
+}