Support forward declared items within blocks

This changes the BlockExpr resolution to iterate Items first, then the
Stmts. This could be handled in HIR by desugaring the BlockExpr by lowering
the block into { <items>; <stmts>; } would also work. But the HIR lowering
of blocks is a little messy right now and we need to clean up the
unreachable lint.

Fixes #531

6 files changed, 68 insertions, 34 deletions

diff --git a/gcc/rust/hir/tree/rust-hir-expr.h b/gcc/rust/hir/tree/rust-hir-expr.h
index c472cab..575d1f6 100644
--- a/gcc/rust/hir/tree/rust-hir-expr.h
+++ b/gcc/rust/hir/tree/rust-hir-expr.h
@@ -2007,15 +2007,6 @@ public:
 
   void accept_vis (HIRVisitor &vis) override;
 
-  void iterate_stmts (std::function<bool (Stmt *)> cb)
-  {
-    for (auto it = statements.begin (); it != statements.end (); it++)
-      {
-	if (!cb (it->get ()))
-	  return;
-      }
-  }
-
   bool is_final_stmt (Stmt *stmt) { return statements.back ().get () == stmt; }
 
   Location get_closing_locus ()
diff --git a/gcc/rust/lint/rust-lint-marklive.h b/gcc/rust/lint/rust-lint-marklive.h
index 7b7b68f..ca5d894 100644
--- a/gcc/rust/lint/rust-lint-marklive.h
+++ b/gcc/rust/lint/rust-lint-marklive.h
@@ -97,10 +97,10 @@ public:
 
   void visit (HIR::BlockExpr &expr) override
   {
-    expr.iterate_stmts ([&] (HIR::Stmt *s) mutable -> bool {
-      s->accept_vis (*this);
-      return true;
-    });
+    for (auto &s : expr.get_statements ())
+      {
+	s->accept_vis (*this);
+      }
     if (expr.has_expr ())
       {
 	expr.get_final_expr ()->accept_vis (*this);
diff --git a/gcc/rust/resolve/rust-ast-resolve.cc b/gcc/rust/resolve/rust-ast-resolve.cc
index 83a15a8..2758c83 100644
--- a/gcc/rust/resolve/rust-ast-resolve.cc
+++ b/gcc/rust/resolve/rust-ast-resolve.cc
@@ -349,7 +349,16 @@ ResolveExpr::visit (AST::BlockExpr &expr)
   resolver->push_new_label_rib (resolver->get_type_scope ().peek ());
 
   for (auto &s : expr.get_statements ())
-    ResolveStmt::go (s.get (), s->get_node_id ());
+    {
+      if (s->is_item ())
+	ResolveStmt::go (s.get (), s->get_node_id ());
+    }
+
+  for (auto &s : expr.get_statements ())
+    {
+      if (!s->is_item ())
+	ResolveStmt::go (s.get (), s->get_node_id ());
+    }
 
   if (expr.has_tail_expr ())
     ResolveExpr::go (expr.get_tail_expr ().get (), expr.get_node_id ());
diff --git a/gcc/rust/typecheck/rust-hir-type-check.cc b/gcc/rust/typecheck/rust-hir-type-check.cc
index 5237082..ca4842a 100644
--- a/gcc/rust/typecheck/rust-hir-type-check.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check.cc
@@ -93,22 +93,37 @@ TypeResolution::Resolve (HIR::Crate &crate)
 void
 TypeCheckExpr::visit (HIR::BlockExpr &expr)
 {
-  expr.iterate_stmts ([&] (HIR::Stmt *s) mutable -> bool {
-    auto resolved = TypeCheckStmt::Resolve (s, inside_loop);
-    if (resolved == nullptr)
-      {
-	rust_error_at (s->get_locus (), "failure to resolve type");
-	return false;
-      }
+  for (auto &s : expr.get_statements ())
+    {
+      if (!s->is_item ())
+	continue;
 
-    if (s->is_unit_check_needed () && !resolved->is_unit ())
-      {
-	auto unit = new TyTy::TupleType (s->get_mappings ().get_hirid ());
-	resolved = unit->unify (resolved);
-      }
+      auto resolved = TypeCheckStmt::Resolve (s.get (), inside_loop);
+      if (resolved == nullptr)
+	{
+	  rust_error_at (s->get_locus (), "failure to resolve type");
+	  return;
+	}
+    }
 
-    return true;
-  });
+  for (auto &s : expr.get_statements ())
+    {
+      if (s->is_item ())
+	continue;
+
+      auto resolved = TypeCheckStmt::Resolve (s.get (), inside_loop);
+      if (resolved == nullptr)
+	{
+	  rust_error_at (s->get_locus (), "failure to resolve type");
+	  return;
+	}
+
+      if (s->is_unit_check_needed () && !resolved->is_unit ())
+	{
+	  auto unit = new TyTy::TupleType (s->get_mappings ().get_hirid ());
+	  resolved = unit->unify (resolved);
+	}
+    }
 
   if (expr.has_expr ())
     infered
diff --git a/gcc/rust/typecheck/rust-tycheck-dump.h b/gcc/rust/typecheck/rust-tycheck-dump.h
index c0681b8..c305d48 100644
--- a/gcc/rust/typecheck/rust-tycheck-dump.h
+++ b/gcc/rust/typecheck/rust-tycheck-dump.h
@@ -94,12 +94,12 @@ public:
   {
     indentation_level++;
 
-    expr.iterate_stmts ([&] (HIR::Stmt *s) mutable -> bool {
-      dump += indent ();
-      s->accept_vis (*this);
-      dump += ";\n";
-      return true;
-    });
+    for (auto &s : expr.get_statements ())
+      {
+	dump += indent ();
+	s->accept_vis (*this);
+	dump += ";\n";
+      }
 
     if (expr.has_expr ())
       {
diff --git a/gcc/testsuite/rust/compile/torture/forward_decl_5.rs b/gcc/testsuite/rust/compile/torture/forward_decl_5.rs
new file mode 100644
index 0000000..73a47fe
--- /dev/null
+++ b/gcc/testsuite/rust/compile/torture/forward_decl_5.rs
@@ -0,0 +1,19 @@
+pub fn main() {
+    let a;
+    a = foo { a: 123, b: 456f32 };
+
+    let mut a = 123;
+    a = bar(a);
+
+    let mut b = 456f32;
+    b = bar(b);
+
+    fn bar<T>(x: T) -> T {
+        x
+    }
+
+    struct foo {
+        a: i32,
+        b: f32,
+    };
+}