Unescape unary method calls

Followup to #2213

Before:
```sh
$ ruby -ve "puts 42.~@"
ruby 3.4.6 (2025-09-16 revision dbd83256b1) +PRISM [x86_64-linux]
-e:1:in '<main>': undefined method '~@' for an instance of Integer (NoMethodError)
Did you mean?  ~
```

After (matches parse.y):
```sh
$ ./miniruby -ve "puts 42.~@"
ruby 3.5.0dev (2025-10-16T03:40:45Z master 1d95d75c3f) +PRISM [x86_64-linux]
-43
```

Author: Earlopain

snapshots/unary_method_calls.txt

@@ -0,0 +1,33 @@
+@ ProgramNode (location: (1,0)-(2,5))
+├── flags: ∅
+├── locals: []
+└── statements:
+    @ StatementsNode (location: (1,0)-(2,5))
+    ├── flags: ∅
+    └── body: (length: 2)
+        ├── @ CallNode (location: (1,0)-(1,5))
+        │   ├── flags: newline
+        │   ├── receiver:
+        │   │   @ IntegerNode (location: (1,0)-(1,2))
+        │   │   ├── flags: static_literal, decimal
+        │   │   └── value: 42
+        │   ├── call_operator_loc: (1,2)-(1,3) = "."
+        │   ├── name: :~
+        │   ├── message_loc: (1,3)-(1,5) = "~@"
+        │   ├── opening_loc: ∅
+        │   ├── arguments: ∅
+        │   ├── closing_loc: ∅
+        │   └── block: ∅
+        └── @ CallNode (location: (2,0)-(2,5))
+            ├── flags: newline
+            ├── receiver:
+            │   @ IntegerNode (location: (2,0)-(2,2))
+            │   ├── flags: static_literal, decimal
+            │   └── value: 42
+            ├── call_operator_loc: (2,2)-(2,3) = "."
+            ├── name: :!
+            ├── message_loc: (2,3)-(2,5) = "!@"
+            ├── opening_loc: ∅
+            ├── arguments: ∅
+            ├── closing_loc: ∅
+            └── block: ∅

src/prism.c

@@ -2721,6 +2721,8 @@ pm_call_node_binary_create(pm_parser_t *parser, pm_node_t *receiver, pm_token_t
     return node;
 }
 
+static const uint8_t * parse_operator_symbol_name(const pm_token_t *);
+
 /**
  * Allocate and initialize a new CallNode node from a call expression.
  */
@@ -2749,7 +2751,11 @@ pm_call_node_call_create(pm_parser_t *parser, pm_node_t *receiver, pm_token_t *o
         pm_node_flag_set((pm_node_t *)node, PM_CALL_NODE_FLAGS_SAFE_NAVIGATION);
     }
 
-    node->name = pm_parser_constant_id_token(parser, message);
+    /**
+    * If the final character is `@` as is the case for `foo.~@`,
+    * we should ignore the @ in the same way we do for symbols.
+    */
+    node->name = pm_parser_constant_id_location(parser, message->start, parse_operator_symbol_name(message));
     return node;
 }
 
@@ -19702,7 +19708,7 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
             pm_parser_scope_pop(parser);
 
             /**
-             * If the final character is @. As is the case when defining
+             * If the final character is `@` as is the case when defining
              * methods to override the unary operators, we should ignore
              * the @ in the same way we do for symbols.
              */

test/prism/fixtures/unary_method_calls.txt

@@ -0,0 +1,2 @@
+42.~@
+42.!@

test/prism/ruby/parser_test.rb

@@ -109,6 +109,9 @@ class ParserTest < TestCase
       # Regex with \c escape
       "unescaping.txt",
       "seattlerb/regexp_esc_C_slash.txt",
+
+      # https://github.com/whitequark/parser/issues/1084
+      "unary_method_calls.txt",
     ]
 
     # These files are failing to translate their lexer output into the lexer

test/prism/ruby/ruby_parser_test.rb

@@ -57,6 +57,7 @@ class RubyParserTest < TestCase
       "spanning_heredoc.txt",
       "symbols.txt",
       "tilde_heredocs.txt",
+      "unary_method_calls.txt",
       "unparser/corpus/literal/literal.txt",
       "while.txt",
       "whitequark/cond_eflipflop.txt",