Diagnose std::move only for single argument version

Closes #1167

Author: hsutter

regression-tests/test-results/version

@@ -1,5 +1,5 @@
 
-cppfront compiler v0.7.1   Build 9716:1345
+cppfront compiler v0.7.1   Build 9717:1027
 Copyright(c) Herb Sutter   All rights reserved
 
 SPDX-License-Identifier: CC-BY-NC-ND-4.0

source/build.info

@@ -1 +1 @@
-"9716:1345"
+"9717:1027"

source/parse.h

@@ -930,6 +930,17 @@ struct postfix_expression_node
         return ops.empty() && expr->is_id_expression();
     }
 
+    auto starts_with_function_call_with_n_parameters(int n) const
+        -> bool
+    {
+        return
+            std::ssize(ops) >= 1
+            && ops.front().op->type() == lexeme::LeftParen
+            && ops.front().expr_list
+            && std::ssize(ops.front().expr_list->expressions) == n
+            ;
+    }
+
     auto is_unqualified_id() const
         -> bool
     {
@@ -6874,11 +6885,14 @@ class parser
         //  Reject "std" :: "move" / "forward"
         assert (term.id->identifier);
         auto first_uid_was_std = (*term.id->identifier == "std");
-        auto first_time_through_loop = true;
 
         n->ids.push_back( std::move(term) );
 
-        while (curr().type() == lexeme::Scope)
+        for ( 
+            auto first_time_through_loop = true;
+            curr().type() == lexeme::Scope;
+            first_time_through_loop = false
+            )
         {
             auto term = qualified_id_node::term{ &curr() };
             next();
@@ -6892,17 +6906,11 @@ class parser
                 first_time_through_loop
                 && first_uid_was_std
                 && term.scope_op->type() == lexeme::Scope
-                )
+                && *term.id->identifier == "forward"
+                ) 
             {
-                if (*term.id->identifier == "move") {
-                    error("std::move is not needed in Cpp2 - use 'move' parameters/arguments instead", false);
-                    return {};
-                }
-                else if (*term.id->identifier == "forward") {
-                    error("std::forward is not needed in Cpp2 - use 'forward' parameters/arguments instead", false);
-                    return {};
-                }
-                first_time_through_loop = false;
+                error("std::forward is not needed in Cpp2 - use 'forward' parameters/arguments instead", false);
+                return {};
             }
             n->ids.push_back( std::move(term) );
         }

source/sema.h

@@ -1511,6 +1511,18 @@ class sema
             }
         }
 
+        if (
+            n.expr->to_string() == "std::move"
+            && n.starts_with_function_call_with_n_parameters(1)
+            )
+        {
+            errors.emplace_back(
+                n.position(),
+                "std::move(one_argument) is not needed in Cpp2 - use 'move' parameters/arguments instead"
+            );
+            return false;
+        }
+
         return true;
     }