[gcc/devel/rust/master] Refactor method call type checking

[gcc/devel/rust/master] Refactor method call type checking

[Thomas Schwinge]

https://gcc.gnu.org/g:662a7a90305f3c5df24765ec6de6c4e56187ae1a

commit 662a7a90305f3c5df24765ec6de6c4e56187ae1a
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Wed Oct 19 10:59:18 2022 +0100

    Refactor method call type checking
    
    We used a visitor interface to handle type checking argument passing on
    method call expressions. This was completely unnessecary as all method
    calls should _always_ be to TyTy::FnType's. The benifit here is that we
    need to reuse this interface to handle method resolution type checking
    for FnTrait calls as closure calls dont have an HIR::MethodExpr so we
    need a more abstract interface so that we can specify the types directly
    with relevant location info.

Diff:
---
 gcc/rust/typecheck/rust-hir-type-check-expr.cc |  3 +-
 gcc/rust/typecheck/rust-tyty-call.cc           | 98 ++++++++++++++++++--------
 gcc/rust/typecheck/rust-tyty-call.h            | 79 ++++++++++-----------
 3 files changed, 106 insertions(+), 74 deletions(-)

diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.cc b/gcc/rust/typecheck/rust-hir-type-check-expr.cc
index df4ddfab1dc..aa044ddb9c8 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.cc
@@ -1162,7 +1162,8 @@ TypeCheckExpr::visit (HIR::MethodCallExpr &expr)
   rust_debug ("type-checking method_call: {%s}", lookup->debug_str ().c_str ());
 
   TyTy::BaseType *function_ret_tyty
-    = TyTy::TypeCheckMethodCallExpr::go (lookup, expr, adjusted_self, context);
+    = TyTy::TypeCheckMethodCallExpr::go (static_cast<TyTy::FnType *> (lookup),
+					 expr, adjusted_self, context);
   if (function_ret_tyty == nullptr
       || function_ret_tyty->get_kind () == TyTy::TypeKind::ERROR)
     {
diff --git a/gcc/rust/typecheck/rust-tyty-call.cc b/gcc/rust/typecheck/rust-tyty-call.cc
index 49aa2ef406e..18a34be09bf 100644
--- a/gcc/rust/typecheck/rust-tyty-call.cc
+++ b/gcc/rust/typecheck/rust-tyty-call.cc
@@ -216,29 +216,77 @@ TypeCheckCallExpr::visit (FnPtr &type)
 
 // method call checker
 
-void
-TypeCheckMethodCallExpr::visit (FnType &type)
+TypeCheckMethodCallExpr::TypeCheckMethodCallExpr (
+  Analysis::NodeMapping call_mappings, std::vector<Argument> &args,
+  Location call_locus, Location receiver_locus, TyTy::BaseType *adjusted_self,
+  Resolver::TypeCheckContext *context)
+  : call_mappings (call_mappings), arguments (args), call_locus (call_locus),
+    receiver_locus (receiver_locus), adjusted_self (adjusted_self),
+    context (context), mappings (Analysis::Mappings::get ())
+{}
+
+BaseType *
+TypeCheckMethodCallExpr::go (FnType *ref, HIR::MethodCallExpr &call,
+			     TyTy::BaseType *adjusted_self,
+			     Resolver::TypeCheckContext *context)
+{
+  std::vector<Argument> args;
+  for (auto &arg : call.get_arguments ())
+    {
+      BaseType *argument_expr_tyty
+	= Resolver::TypeCheckExpr::Resolve (arg.get ());
+      if (argument_expr_tyty->get_kind () == TyTy::TypeKind::ERROR)
+	{
+	  rust_error_at (arg->get_locus (),
+			 "failed to resolve type for argument");
+	  return new ErrorType (ref->get_ref ());
+	}
+
+      Argument a (arg->get_mappings (), argument_expr_tyty, arg->get_locus ());
+      args.push_back (std::move (a));
+    }
+
+  TypeCheckMethodCallExpr checker (call.get_mappings (), args,
+				   call.get_locus (),
+				   call.get_receiver ()->get_locus (),
+				   adjusted_self, context);
+  return checker.check (*ref);
+}
+
+BaseType *
+TypeCheckMethodCallExpr::go (FnType *ref, Analysis::NodeMapping call_mappings,
+			     std::vector<Argument> &args, Location call_locus,
+			     Location receiver_locus,
+			     TyTy::BaseType *adjusted_self,
+			     Resolver::TypeCheckContext *context)
+{
+  TypeCheckMethodCallExpr checker (call_mappings, args, call_locus,
+				   receiver_locus, adjusted_self, context);
+  return checker.check (*ref);
+}
+
+BaseType *
+TypeCheckMethodCallExpr::check (FnType &type)
 {
   Resolver::TypeCheckBase::unify_site (
-    call.get_mappings ().get_hirid (), TyWithLocation (type.get_self_type ()),
-    TyWithLocation (adjusted_self, call.get_receiver ()->get_locus ()),
-    call.get_locus ());
+    call_mappings.get_hirid (), TyWithLocation (type.get_self_type ()),
+    TyWithLocation (adjusted_self, receiver_locus), call_locus);
 
   // +1 for the receiver self
-  size_t num_args_to_call = call.num_params () + 1;
+  size_t num_args_to_call = arguments.size () + 1;
   if (num_args_to_call != type.num_params ())
     {
-      rust_error_at (call.get_locus (),
+      rust_error_at (call_locus,
 		     "unexpected number of arguments %lu expected %lu",
-		     (unsigned long) call.num_params (),
+		     (unsigned long) num_args_to_call,
 		     (unsigned long) type.num_params ());
-      return;
+      return new ErrorType (type.get_ref ());
     }
 
   size_t i = 1;
-  for (auto &argument : call.get_arguments ())
+  for (auto &argument : arguments)
     {
-      Location arg_locus = argument->get_locus ();
+      Location arg_locus = argument.get_locus ();
 
       auto fnparam = type.param_at (i);
       HIR::Pattern *fn_param_pattern = fnparam.first;
@@ -248,25 +296,15 @@ TypeCheckMethodCallExpr::visit (FnType &type)
 	    ? mappings->lookup_location (param_ty->get_ref ())
 	    : fn_param_pattern->get_locus ();
 
-      auto argument_expr_tyty
-	= Resolver::TypeCheckExpr::Resolve (argument.get ());
-      if (argument_expr_tyty->get_kind () == TyTy::TypeKind::ERROR)
-	{
-	  rust_error_at (
-	    argument->get_locus (),
-	    "failed to resolve type for argument expr in CallExpr");
-	  return;
-	}
-
-      HirId coercion_side_id = argument->get_mappings ().get_hirid ();
+      auto argument_expr_tyty = argument.get_argument_type ();
+      HirId coercion_side_id = argument.get_mappings ().get_hirid ();
       auto resolved_argument_type = Resolver::TypeCheckBase::coercion_site (
 	coercion_side_id, TyWithLocation (param_ty, param_locus),
-	TyWithLocation (argument_expr_tyty, arg_locus), argument->get_locus ());
+	TyWithLocation (argument_expr_tyty, arg_locus), arg_locus);
       if (resolved_argument_type->get_kind () == TyTy::TypeKind::ERROR)
 	{
-	  rust_error_at (argument->get_locus (),
-			 "Type Resolution failure on parameter");
-	  return;
+	  rust_error_at (arg_locus, "Type Resolution failure on parameter");
+	  return new ErrorType (type.get_ref ());
 	}
 
       i++;
@@ -274,15 +312,15 @@ TypeCheckMethodCallExpr::visit (FnType &type)
 
   if (i != num_args_to_call)
     {
-      rust_error_at (call.get_locus (),
+      rust_error_at (call_locus,
 		     "unexpected number of arguments %lu expected %lu",
-		     (unsigned long) i, (unsigned long) call.num_params ());
-      return;
+		     (unsigned long) i, (unsigned long) arguments.size ());
+      return new ErrorType (type.get_ref ());
     }
 
   type.monomorphize ();
 
-  resolved = type.get_return_type ()->monomorphized_clone ();
+  return type.get_return_type ()->monomorphized_clone ();
 }
 
 } // namespace TyTy
diff --git a/gcc/rust/typecheck/rust-tyty-call.h b/gcc/rust/typecheck/rust-tyty-call.h
index 51817e6446d..eef567ac419 100644
--- a/gcc/rust/typecheck/rust-tyty-call.h
+++ b/gcc/rust/typecheck/rust-tyty-call.h
@@ -84,58 +84,51 @@ private:
   Analysis::Mappings *mappings;
 };
 
-class TypeCheckMethodCallExpr : private TyVisitor
+class Argument
 {
 public:
-  // Resolve the Method parameters and return back the return type
-  static BaseType *go (BaseType *ref, HIR::MethodCallExpr &call,
-		       TyTy::BaseType *adjusted_self,
-		       Resolver::TypeCheckContext *context)
-  {
-    TypeCheckMethodCallExpr checker (call, adjusted_self, context);
-    ref->accept_vis (checker);
-    return checker.resolved;
-  }
+  Argument (Analysis::NodeMapping mapping, BaseType *argument_type,
+	    Location locus)
+    : mapping (mapping), argument_type (argument_type), locus (locus)
+  {}
 
-  void visit (InferType &) override { gcc_unreachable (); }
-  void visit (TupleType &) override { gcc_unreachable (); }
-  void visit (ArrayType &) override { gcc_unreachable (); }
-  void visit (SliceType &) override { gcc_unreachable (); }
-  void visit (BoolType &) override { gcc_unreachable (); }
-  void visit (IntType &) override { gcc_unreachable (); }
-  void visit (UintType &) override { gcc_unreachable (); }
-  void visit (FloatType &) override { gcc_unreachable (); }
-  void visit (USizeType &) override { gcc_unreachable (); }
-  void visit (ISizeType &) override { gcc_unreachable (); }
-  void visit (ErrorType &) override { gcc_unreachable (); }
-  void visit (ADTType &) override { gcc_unreachable (); };
-  void visit (CharType &) override { gcc_unreachable (); }
-  void visit (ReferenceType &) override { gcc_unreachable (); }
-  void visit (PointerType &) override { gcc_unreachable (); }
-  void visit (ParamType &) override { gcc_unreachable (); }
-  void visit (StrType &) override { gcc_unreachable (); }
-  void visit (NeverType &) override { gcc_unreachable (); }
-  void visit (PlaceholderType &) override { gcc_unreachable (); }
-  void visit (ProjectionType &) override { gcc_unreachable (); }
-  void visit (DynamicObjectType &) override { gcc_unreachable (); }
+  Location get_locus () const { return locus; }
 
-  // FIXME
-  void visit (FnPtr &type) override { gcc_unreachable (); }
+  BaseType *get_argument_type () { return argument_type; }
 
-  // call fns
-  void visit (FnType &type) override;
-  void visit (ClosureType &type) override { gcc_unreachable (); }
+  Analysis::NodeMapping get_mappings () const { return mapping; }
 
 private:
-  TypeCheckMethodCallExpr (HIR::MethodCallExpr &c,
+  Analysis::NodeMapping mapping;
+  BaseType *argument_type;
+  Location locus;
+};
+
+class TypeCheckMethodCallExpr
+{
+public:
+  static BaseType *go (FnType *ref, HIR::MethodCallExpr &call,
+		       TyTy::BaseType *adjusted_self,
+		       Resolver::TypeCheckContext *context);
+
+  static BaseType *go (FnType *ref, Analysis::NodeMapping call_mappings,
+		       std::vector<Argument> &args, Location call_locus,
+		       Location receiver_locus, TyTy::BaseType *adjusted_self,
+		       Resolver::TypeCheckContext *context);
+
+protected:
+  BaseType *check (FnType &type);
+
+  TypeCheckMethodCallExpr (Analysis::NodeMapping call_mappings,
+			   std::vector<Argument> &args, Location call_locus,
+			   Location receiver_locus,
 			   TyTy::BaseType *adjusted_self,
-			   Resolver::TypeCheckContext *context)
-    : resolved (nullptr), call (c), adjusted_self (adjusted_self),
-      context (context), mappings (Analysis::Mappings::get ())
-  {}
+			   Resolver::TypeCheckContext *context);
 
-  BaseType *resolved;
-  HIR::MethodCallExpr &call;
+  Analysis::NodeMapping call_mappings;
+  std::vector<Argument> &arguments;
+  Location call_locus;
+  Location receiver_locus;
   TyTy::BaseType *adjusted_self;
   Resolver::TypeCheckContext *context;
   Analysis::Mappings *mappings;