Ensure method resolution resolves to an actual method

We need to check for rustc --explain E0599 so when we have a method call
that it must resolve to an actual method impl item.

5 files changed, 49 insertions, 93 deletions

diff --git a/gcc/rust/hir/tree/rust-hir-item.h b/gcc/rust/hir/tree/rust-hir-item.h
index 648999b..fc67d60 100644
--- a/gcc/rust/hir/tree/rust-hir-item.h
+++ b/gcc/rust/hir/tree/rust-hir-item.h
@@ -745,6 +745,8 @@ public:
 
   Location get_locus () const { return locus; }
 
+  Location get_impl_locus () const final { return get_locus (); }
+
   std::unique_ptr<BlockExpr> &get_function_body () { return function_body; }
   const std::unique_ptr<BlockExpr> &get_function_body () const
   {
@@ -1366,6 +1368,8 @@ public:
 
   Location get_locus () const { return locus; }
 
+  Location get_impl_locus () const final { return get_locus (); }
+
   void accept_vis (HIRVisitor &vis) override;
 
   Analysis::NodeMapping get_impl_mappings () const override
@@ -2266,6 +2270,8 @@ public:
 
   Location get_locus () const { return locus; }
 
+  Location get_impl_locus () const final { return get_locus (); }
+
   void accept_vis (HIRVisitor &vis) override;
 
   Type *get_type () { return type.get (); }
diff --git a/gcc/rust/hir/tree/rust-hir.h b/gcc/rust/hir/tree/rust-hir.h
index 244ff3d..f6fa62d 100644
--- a/gcc/rust/hir/tree/rust-hir.h
+++ b/gcc/rust/hir/tree/rust-hir.h
@@ -1295,6 +1295,8 @@ public:
   virtual void accept_vis (HIRVisitor &vis) = 0;
 
   virtual Analysis::NodeMapping get_impl_mappings () const = 0;
+
+  virtual Location get_impl_locus () const = 0;
 };
 
 // Abstract base class for items used in a trait impl
diff --git a/gcc/rust/typecheck/rust-hir-method-resolve.h b/gcc/rust/typecheck/rust-hir-method-resolve.h
deleted file mode 100644
index b2391e3..0000000
--- a/gcc/rust/typecheck/rust-hir-method-resolve.h
+++ /dev/null
@@ -1,67 +0,0 @@
-// Copyright (C) 2020 Free Software Foundation, Inc.
-
-// This file is part of GCC.
-
-// GCC is free software; you can redistribute it and/or modify it under
-// the terms of the GNU General Public License as published by the Free
-// Software Foundation; either version 3, or (at your option) any later
-// version.
-
-// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or
-// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-// for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with GCC; see the file COPYING3.  If not see
-// <http://www.gnu.org/licenses/>.
-
-#ifndef RUST_HIR_METHOD_RESOLVE_H
-#define RUST_HIR_METHOD_RESOLVE_H
-
-#include "rust-hir-type-check-base.h"
-#include "rust-hir-full.h"
-#include "rust-tyty.h"
-#include "rust-hir-path-probe.h"
-#include "rust-substitution-mapper.h"
-
-namespace Rust {
-namespace Resolver {
-
-class MethodResolution : public TypeCheckBase
-{
-  using Rust::Resolver::TypeCheckBase::visit;
-
-public:
-  static std::vector<PathProbeCandidate>
-  Probe (std::vector<PathProbeCandidate> &path_candidates)
-  {
-    MethodResolution probe;
-    for (auto &c : path_candidates)
-      probe.process_candidate (c);
-
-    return probe.candidates;
-  }
-
-  void process_candidate (PathProbeCandidate &candidate)
-  {
-    is_method_flag = false;
-    candidate.impl_item->accept_vis (*this);
-
-    if (is_method_flag)
-      candidates.push_back (candidate);
-  }
-
-  void visit (HIR::Method &method) override { is_method_flag = true; }
-
-private:
-  MethodResolution () : TypeCheckBase () {}
-
-  bool is_method_flag;
-  std::vector<PathProbeCandidate> candidates;
-};
-
-} // namespace Resolver
-} // namespace Rust
-
-#endif // RUST_HIR_METHOD_RESOLVE_H
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index d82e82b..5df6b70 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -24,7 +24,6 @@
 #include "rust-tyty.h"
 #include "rust-tyty-call.h"
 #include "rust-hir-type-check-struct-field.h"
-#include "rust-hir-method-resolve.h"
 #include "rust-hir-path-probe.h"
 #include "rust-substitution-mapper.h"
 #include "rust-hir-const-fold.h"
@@ -221,43 +220,45 @@ public:
 		       "failed to resolve the PathExprSegment to any Method");
 	return;
       }
-
-    // filter all methods
-    auto possible_methods = MethodResolution::Probe (candidates);
-    if (possible_methods.size () == 0)
-      {
-	rust_error_at (expr.get_method_name ().get_locus (),
-		       "no method named %s found in scope",
-		       expr.get_method_name ().as_string ().c_str ());
-	return;
-      }
-    else if (possible_methods.size () > 1)
+    else if (candidates.size () > 1)
       {
 	ReportMultipleCandidateError::Report (
-	  possible_methods, expr.get_method_name ().get_segment (),
+	  candidates, expr.get_method_name ().get_segment (),
 	  expr.get_method_name ().get_locus ());
 	return;
       }
 
-    auto resolved_candidate = possible_methods.at (0);
+    auto resolved_candidate = candidates.at (0);
     HIR::InherentImplItem *resolved_method = resolved_candidate.impl_item;
     TyTy::BaseType *lookup_tyty = resolved_candidate.ty;
 
+    if (lookup_tyty->get_kind () != TyTy::TypeKind::FNDEF)
+      {
+	RichLocation r (expr.get_method_name ().get_locus ());
+	r.add_range (resolved_method->get_impl_locus ());
+	rust_error_at (r, "associated impl item is not a method");
+	return;
+      }
+
     TyTy::BaseType *lookup = lookup_tyty;
-    if (lookup_tyty->get_kind () == TyTy::TypeKind::FNDEF)
+    TyTy::FnType *fn = static_cast<TyTy::FnType *> (lookup);
+    if (!fn->is_method ())
       {
-	TyTy::FnType *fn = static_cast<TyTy::FnType *> (lookup);
-	if (receiver_tyty->get_kind () == TyTy::TypeKind::ADT)
+	RichLocation r (expr.get_method_name ().get_locus ());
+	r.add_range (resolved_method->get_impl_locus ());
+	rust_error_at (r, "associated function is not a method");
+	return;
+      }
+
+    if (receiver_tyty->get_kind () == TyTy::TypeKind::ADT)
+      {
+	TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (receiver_tyty);
+	if (adt->has_substitutions () && fn->needs_substitution ())
 	  {
-	    TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (receiver_tyty);
-	    if (adt->has_substitutions () && fn->needs_substitution ())
-	      {
-		rust_assert (adt->was_substituted ());
-		auto used_args_in_prev_segment = GetUsedSubstArgs::From (adt);
-		lookup
-		  = SubstMapperInternal::Resolve (fn,
-						  used_args_in_prev_segment);
-	      }
+	    rust_assert (adt->was_substituted ());
+	    auto used_args_in_prev_segment = GetUsedSubstArgs::From (adt);
+	    lookup
+	      = SubstMapperInternal::Resolve (fn, used_args_in_prev_segment);
 	  }
       }
 
diff --git a/gcc/testsuite/rust.test/xfail_compile/method1.rs b/gcc/testsuite/rust.test/xfail_compile/method1.rs
new file mode 100644
index 0000000..51bc821
--- /dev/null
+++ b/gcc/testsuite/rust.test/xfail_compile/method1.rs
@@ -0,0 +1,14 @@
+// { dg-excess-errors "Noisy error and debug" }
+struct Foo(i32);
+
+impl Foo {
+    fn test() {}
+}
+
+pub fn main() {
+    let a;
+    a = Foo(123);
+
+    a.test()
+    // { dg-error "associated function is not a method" "" { target *-*-* } .-1 }
+}