ast: Add qualified_call helper to Builder

This patch implements the `qualified_call` helper method in the `Builder`
class. This logic was previously intended to be a local helper in
`DeriveClone`, but moving it to the `Builder` allows it to be reused
across the compiler for constructing qualified function calls.

It updates `DeriveClone::clone_call` to use this new `Builder` method,
simplifying the code and resolving the TODO.

Fixes #4393

gcc/rust/ChangeLog:

	* ast/rust-ast-builder.h (Builder::qualified_call): New method declaration.
	* ast/rust-ast-builder.cc (Builder::qualified_call): Implement new method.
	* expand/rust-derive-clone.cc (DeriveClone::clone_call): Use builder.qualified_call.

Signed-off-by: Jayant Chauhan <0001jayant@gmail.com>

Author: Pasta-coder

gcc/rust/ast/rust-ast-builder.cc

@@ -737,5 +737,15 @@ Builder::new_generic_args (GenericArgs &args)
 		      std::move (binding_args), locus);
 }
 
+std::unique_ptr<Expr>
+Builder::qualified_call (std::vector<std::string> &&segments,
+			 std::vector<std::unique_ptr<Expr>> &&args) const
+{
+  auto path = std::unique_ptr<Expr> (
+    new PathInExpression (path_in_expression (std::move (segments))));
+
+  return call (std::move (path), std::move (args));
+}
+
 } // namespace AST
 } // namespace Rust

gcc/rust/ast/rust-ast-builder.h

@@ -169,6 +169,10 @@ class Builder
 				std::vector<PathExprSegment> &&segments
 				= {}) const;
 
+  std::unique_ptr<Expr>
+  qualified_call (std::vector<std::string> &&segments,
+		  std::vector<std::unique_ptr<Expr>> &&args) const;
+
   /* Self parameter for a function definition (`&self`) */
   std::unique_ptr<Param> self_ref_param (bool mutability = false) const;
   /* A regular named function parameter for a definition (`a: type`) */

gcc/rust/expand/rust-derive-clone.cc

@@ -42,13 +42,10 @@ DeriveClone::clone_call (std::unique_ptr<Expr> &&to_clone)
 
   // Not sure how to call it properly in the meantime...
 
-  auto path = std::unique_ptr<Expr> (
-    new PathInExpression (builder.path_in_expression ({"Clone", "clone"})));
-
   auto args = std::vector<std::unique_ptr<Expr>> ();
   args.emplace_back (std::move (to_clone));
 
-  return builder.call (std::move (path), std::move (args));
+  return builder.qualified_call ({"Clone", "clone"}, std::move (args));
 }
 
 /**
@@ -104,8 +101,6 @@ DeriveClone::clone_impl (
 			     std::move (generics.impl));
 }
 
-// TODO: Create new `make_qualified_call` helper function
-
 DeriveClone::DeriveClone (location_t loc)
   : DeriveVisitor (loc), expanded (nullptr)
 {}