[ruby/prism] Fix associativity of binary range with begin-less range

Fix https://github.com/ruby/prism/pull/1828

https://github.com/ruby/prism/commit/22c0640e48

4 files changed, 59 insertions, 17 deletions

diff --git a/prism/prism.c b/prism/prism.c
index db9c1ad7e1..885470137d 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -10202,6 +10202,8 @@ pm_binding_powers_t pm_binding_powers[PM_TOKEN_MAXIMUM] = {
     // .. ...
     [PM_TOKEN_DOT_DOT] = NON_ASSOCIATIVE(PM_BINDING_POWER_RANGE),
     [PM_TOKEN_DOT_DOT_DOT] = NON_ASSOCIATIVE(PM_BINDING_POWER_RANGE),
+    [PM_TOKEN_UDOT_DOT] = RIGHT_ASSOCIATIVE_UNARY(PM_BINDING_POWER_LOGICAL_OR),
+    [PM_TOKEN_UDOT_DOT_DOT] = RIGHT_ASSOCIATIVE_UNARY(PM_BINDING_POWER_LOGICAL_OR),
 
     // ||
     [PM_TOKEN_PIPE_PIPE] = LEFT_ASSOCIATIVE(PM_BINDING_POWER_LOGICAL_OR),
@@ -13956,7 +13958,7 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power) {
             pm_token_t operator = parser->current;
             parser_lex(parser);
 
-            pm_node_t *right = parse_expression(parser, binding_power, PM_ERR_EXPECT_EXPRESSION_AFTER_OPERATOR);
+            pm_node_t *right = parse_expression(parser, pm_binding_powers[operator.type].left, PM_ERR_EXPECT_EXPRESSION_AFTER_OPERATOR);
             return (pm_node_t *) pm_range_node_create(parser, NULL, &operator, right);
         }
         case PM_TOKEN_FLOAT:
@@ -16766,6 +16768,7 @@ parse_expression_infix(pm_parser_t *parser, pm_node_t *node, pm_binding_power_t
 static pm_node_t *
 parse_expression(pm_parser_t *parser, pm_binding_power_t binding_power, pm_diagnostic_id_t diag_id) {
     pm_token_t recovery = parser->previous;
+    bool is_udot = parser->current.type == PM_TOKEN_UDOT_DOT || parser->current.type == PM_TOKEN_UDOT_DOT_DOT;
     pm_node_t *node = parse_expression_prefix(parser, binding_power);
 
     switch (PM_NODE_TYPE(node)) {
@@ -16789,6 +16792,14 @@ parse_expression(pm_parser_t *parser, pm_binding_power_t binding_power, pm_diagn
             break;
     }
 
+    // Range operators are non-associative, so that it does not associate with
+    // other range operators (i.e. `..1..` should be rejected.)
+    // For this reason, we check such a case for unary ranges here, and if so,
+    // it returns the node immediately,
+    if (is_udot && pm_binding_powers[parser->current.type].left >= PM_BINDING_POWER_RANGE) {
+        return node;
+    }
+
     // Otherwise we'll look and see if the next token can be parsed as an infix
     // operator. If it can, then we'll parse it using parse_expression_infix.
     pm_binding_powers_t current_binding_powers;
diff --git a/test/prism/errors_test.rb b/test/prism/errors_test.rb
index bc3f3ebee9..5572a3254f 100644
--- a/test/prism/errors_test.rb
+++ b/test/prism/errors_test.rb
@@ -1770,6 +1770,21 @@ module Prism
       ]
     end
 
+    def test_binary_range_with_left_unary_range
+      source = <<~RUBY
+        ..1..
+        ...1..
+      RUBY
+      message1 = 'Expected a newline or semicolon after the statement'
+      message2 =  'Cannot parse the expression'
+      assert_errors expression(source), source, [
+        [message1, 3..3],
+        [message2, 3..3],
+        [message1, 10..10],
+        [message2, 10..10],
+      ]
+    end
+
     private
 
     def assert_errors(expected, source, errors, compare_ripper: RUBY_ENGINE == "ruby")
diff --git a/test/prism/fixtures/ranges.txt b/test/prism/fixtures/ranges.txt
index 55c0ade965..c9bfe50399 100644
--- a/test/prism/fixtures/ranges.txt
+++ b/test/prism/fixtures/ranges.txt
@@ -15,3 +15,5 @@ foo[...2]
 { foo: ..bar }
 
 (1..)
+
+1 .. ..1
diff --git a/test/prism/snapshots/ranges.txt b/test/prism/snapshots/ranges.txt
index 3c7892f29b..f52f93633c 100644
--- a/test/prism/snapshots/ranges.txt
+++ b/test/prism/snapshots/ranges.txt
@@ -1,8 +1,8 @@
-@ ProgramNode (location: (1,0)-(17,5))
+@ ProgramNode (location: (1,0)-(19,8))
 ├── locals: []
 └── statements:
-    @ StatementsNode (location: (1,0)-(17,5))
-    └── body: (length: 9)
+    @ StatementsNode (location: (1,0)-(19,8))
+    └── body: (length: 10)
         ├── @ ParenthesesNode (location: (1,0)-(1,6))
         │   ├── body:
         │   │   @ StatementsNode (location: (1,1)-(1,5))
@@ -146,16 +146,30 @@
         │   │       │   └── flags: ∅
         │   │       └── operator_loc: ∅
         │   └── closing_loc: (15,13)-(15,14) = "}"
-        └── @ ParenthesesNode (location: (17,0)-(17,5))
-            ├── body:
-            │   @ StatementsNode (location: (17,1)-(17,4))
-            │   └── body: (length: 1)
-            │       └── @ RangeNode (location: (17,1)-(17,4))
-            │           ├── left:
-            │           │   @ IntegerNode (location: (17,1)-(17,2))
-            │           │   └── flags: decimal
-            │           ├── right: ∅
-            │           ├── operator_loc: (17,2)-(17,4) = ".."
-            │           └── flags: ∅
-            ├── opening_loc: (17,0)-(17,1) = "("
-            └── closing_loc: (17,4)-(17,5) = ")"
+        ├── @ ParenthesesNode (location: (17,0)-(17,5))
+        │   ├── body:
+        │   │   @ StatementsNode (location: (17,1)-(17,4))
+        │   │   └── body: (length: 1)
+        │   │       └── @ RangeNode (location: (17,1)-(17,4))
+        │   │           ├── left:
+        │   │           │   @ IntegerNode (location: (17,1)-(17,2))
+        │   │           │   └── flags: decimal
+        │   │           ├── right: ∅
+        │   │           ├── operator_loc: (17,2)-(17,4) = ".."
+        │   │           └── flags: ∅
+        │   ├── opening_loc: (17,0)-(17,1) = "("
+        │   └── closing_loc: (17,4)-(17,5) = ")"
+        └── @ RangeNode (location: (19,0)-(19,8))
+            ├── left:
+            │   @ IntegerNode (location: (19,0)-(19,1))
+            │   └── flags: decimal
+            ├── right:
+            │   @ RangeNode (location: (19,5)-(19,8))
+            │   ├── left: ∅
+            │   ├── right:
+            │   │   @ IntegerNode (location: (19,7)-(19,8))
+            │   │   └── flags: decimal
+            │   ├── operator_loc: (19,5)-(19,7) = ".."
+            │   └── flags: ∅
+            ├── operator_loc: (19,2)-(19,4) = ".."
+            └── flags: ∅