[ruby/prism] Handle invalid commas in arguments, parameters, and arrays

https://github.com/ruby/prism/commit/023e894b74

prism/config.yml

@@ -141,6 +141,7 @@ errors:
   - INSTANCE_VARIABLE_BARE
   - INVALID_BLOCK_EXIT
   - INVALID_CHARACTER
+  - INVALID_COMMA
   - INVALID_ENCODING_MAGIC_COMMENT
   - INVALID_ESCAPE_CHARACTER
   - INVALID_FLOAT_EXPONENT

prism/prism.c

@@ -2107,14 +2107,6 @@ pm_array_node_create(pm_parser_t *parser, const pm_token_t *opening) {
     return node;
 }
 
-/**
- * Return the size of the given array node.
- */
-static inline size_t
-pm_array_node_size(pm_array_node_t *node) {
-    return node->elements.size;
-}
-
 /**
  * Append an argument to an array node.
  */
@@ -14121,8 +14113,8 @@ static void
 parse_arguments(pm_parser_t *parser, pm_arguments_t *arguments, bool accepts_forwarding, pm_token_type_t terminator, uint16_t depth) {
     pm_binding_power_t binding_power = pm_binding_powers[parser->current.type].left;
 
-    // First we need to check if the next token is one that could be the start of
-    // an argument. If it's not, then we can just return.
+    // First we need to check if the next token is one that could be the start
+    // of an argument. If it's not, then we can just return.
     if (
         match2(parser, terminator, PM_TOKEN_EOF) ||
         (binding_power != PM_BINDING_POWER_UNSET && binding_power < PM_BINDING_POWER_RANGE) ||
@@ -14309,23 +14301,32 @@ parse_arguments(pm_parser_t *parser, pm_arguments_t *arguments, bool accepts_for
         // If parsing the argument failed, we need to stop parsing arguments.
         if (PM_NODE_TYPE_P(argument, PM_MISSING_NODE) || parser->recovering) break;
 
-        // If the terminator of these arguments is not EOF, then we have a specific
-        // token we're looking for. In that case we can accept a newline here
-        // because it is not functioning as a statement terminator.
-        if (terminator != PM_TOKEN_EOF) accept1(parser, PM_TOKEN_NEWLINE);
-
-        if (parser->previous.type == PM_TOKEN_COMMA && parsed_bare_hash) {
-            // If we previously were on a comma and we just parsed a bare hash, then
-            // we want to continue parsing arguments. This is because the comma was
-            // grabbed up by the hash parser.
-        } else {
-            // If there is no comma at the end of the argument list then we're done
-            // parsing arguments and can break out of this loop.
-            if (!accept1(parser, PM_TOKEN_COMMA)) break;
+        // If the terminator of these arguments is not EOF, then we have a
+        // specific token we're looking for. In that case we can accept a
+        // newline here because it is not functioning as a statement terminator.
+        bool accepted_newline = false;
+        if (terminator != PM_TOKEN_EOF) {
+            accepted_newline = accept1(parser, PM_TOKEN_NEWLINE);
         }
 
-        // If we hit the terminator, then that means we have a trailing comma so we
-        // can accept that output as well.
+        if (parser->previous.type == PM_TOKEN_COMMA && parsed_bare_hash) {
+            // If we previously were on a comma and we just parsed a bare hash,
+            // then we want to continue parsing arguments. This is because the
+            // comma was grabbed up by the hash parser.
+        } else if (accept1(parser, PM_TOKEN_COMMA)) {
+            // If there was a comma, then we need to check if we also accepted a
+            // newline. If we did, then this is a syntax error.
+            if (accepted_newline) {
+                pm_parser_err_previous(parser, PM_ERR_INVALID_COMMA);
+            }
+        } else {
+            // If there is no comma at the end of the argument list then we're
+            // done parsing arguments and can break out of this loop.
+            break;
+        }
+
+        // If we hit the terminator, then that means we have a trailing comma so
+        // we can accept that output as well.
         if (match1(parser, terminator)) break;
     }
 }
@@ -14482,13 +14483,14 @@ parse_parameters(
     bool accepts_blocks_in_defaults,
     uint16_t depth
 ) {
-    pm_parameters_node_t *params = pm_parameters_node_create(parser);
-    bool looping = true;
-
     pm_do_loop_stack_push(parser, false);
+
+    pm_parameters_node_t *params = pm_parameters_node_create(parser);
     pm_parameters_order_t order = PM_PARAMETERS_ORDER_NONE;
 
-    do {
+    while (true) {
+        bool parsing = true;
+
         switch (parser->current.type) {
             case PM_TOKEN_PARENTHESIS_LEFT: {
                 update_parameter_state(parser, &parser->current, &order);
@@ -14623,7 +14625,7 @@ parse_parameters(
                     // then we can put a missing node in its place and stop parsing the
                     // parameters entirely now.
                     if (parser->recovering) {
-                        looping = false;
+                        parsing = false;
                         break;
                     }
                 } else if (order > PM_PARAMETERS_ORDER_AFTER_OPTIONAL) {
@@ -14681,7 +14683,7 @@ parse_parameters(
                         context_pop(parser);
 
                         if (uses_parentheses) {
-                            looping = false;
+                            parsing = false;
                             break;
                         }
 
@@ -14725,7 +14727,7 @@ parse_parameters(
                         // then we can put a missing node in its place and stop parsing the
                         // parameters entirely now.
                         if (parser->recovering) {
-                            looping = false;
+                            parsing = false;
                             break;
                         }
                     }
@@ -14827,14 +14829,31 @@ parse_parameters(
                     }
                 }
 
-                looping = false;
+                parsing = false;
                 break;
         }
 
-        if (looping && uses_parentheses) {
-            accept1(parser, PM_TOKEN_NEWLINE);
+        // If we hit some kind of issue while parsing the parameter, this would
+        // have been set to false. In that case, we need to break out of the
+        // loop.
+        if (!parsing) break;
+
+        bool accepted_newline = false;
+        if (uses_parentheses) {
+            accepted_newline = accept1(parser, PM_TOKEN_NEWLINE);
         }
-    } while (looping && accept1(parser, PM_TOKEN_COMMA));
+
+        if (accept1(parser, PM_TOKEN_COMMA)) {
+            // If there was a comma, but we also accepted a newline, then this
+            // is a syntax error.
+            if (accepted_newline) {
+                pm_parser_err_previous(parser, PM_ERR_INVALID_COMMA);
+            }
+        } else {
+            // If there was no comma, then we're done parsing parameters.
+            break;
+        }
+    }
 
     pm_do_loop_stack_pop(parser);
 
@@ -17973,19 +17992,31 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
             bool parsed_bare_hash = false;
 
             while (!match2(parser, PM_TOKEN_BRACKET_RIGHT, PM_TOKEN_EOF)) {
+                bool accepted_newline = accept1(parser, PM_TOKEN_NEWLINE);
+
                 // Handle the case where we don't have a comma and we have a
                 // newline followed by a right bracket.
-                if (accept1(parser, PM_TOKEN_NEWLINE) && match1(parser, PM_TOKEN_BRACKET_RIGHT)) {
+                if (accepted_newline && match1(parser, PM_TOKEN_BRACKET_RIGHT)) {
                     break;
                 }
 
                 // Ensure that we have a comma between elements in the array.
-                if ((pm_array_node_size(array) != 0) && !accept1(parser, PM_TOKEN_COMMA)) {
-                    const uint8_t *location = parser->previous.end;
-                    PM_PARSER_ERR_FORMAT(parser, location, location, PM_ERR_ARRAY_SEPARATOR, pm_token_type_human(parser->current.type));
+                if (array->elements.size > 0) {
+                    if (accept1(parser, PM_TOKEN_COMMA)) {
+                        // If there was a comma but we also accepts a newline,
+                        // then this is a syntax error.
+                        if (accepted_newline) {
+                            pm_parser_err_previous(parser, PM_ERR_INVALID_COMMA);
+                        }
+                    } else {
+                        // If there was no comma, then we need to add a syntax
+                        // error.
+                        const uint8_t *location = parser->previous.end;
+                        PM_PARSER_ERR_FORMAT(parser, location, location, PM_ERR_ARRAY_SEPARATOR, pm_token_type_human(parser->current.type));
 
-                    parser->previous.start = location;
-                    parser->previous.type = PM_TOKEN_MISSING;
+                        parser->previous.start = location;
+                        parser->previous.type = PM_TOKEN_MISSING;
+                    }
                 }
 
                 // If we have a right bracket immediately following a comma,

prism/templates/src/diagnostic.c.erb

@@ -223,6 +223,7 @@ static const pm_diagnostic_data_t diagnostic_messages[PM_DIAGNOSTIC_ID_MAX] = {
     [PM_ERR_INCOMPLETE_VARIABLE_INSTANCE]       = { "'%.*s' is not allowed as an instance variable name", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INSTANCE_VARIABLE_BARE]             = { "'@' without identifiers is not allowed as an instance variable name", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INVALID_BLOCK_EXIT]                 = { "Invalid %s", PM_ERROR_LEVEL_SYNTAX },
+    [PM_ERR_INVALID_COMMA]                      = { "invalid comma", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INVALID_ESCAPE_CHARACTER]           = { "Invalid escape character syntax", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INVALID_FLOAT_EXPONENT]             = { "invalid exponent", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INVALID_LOCAL_VARIABLE_READ]        = { "identifier %.*s is not valid to get", PM_ERROR_LEVEL_SYNTAX },

test/prism/errors/arguments_invalid_comma.txt

@@ -0,0 +1,4 @@
+p(a,b
+,)
+^ invalid comma
+

test/prism/errors/array_invalid_comma.txt

@@ -0,0 +1,4 @@
+[a
+,]
+^ invalid comma
+

test/prism/errors/parameters_invalid_comma.txt

@@ -0,0 +1,4 @@
+def f(a
+,b);end
+^ invalid comma
+