diagnostic.c

#include "prism/diagnostic.h"

/** This struct holds the data for each diagnostic. */
typedef struct {
    /** The message associated with the diagnostic. */
    const char* message;

    /** The level associated with the diagnostic. */
    uint8_t level;
} pm_diagnostic_data_t;

/**
 * ## Message composition
 *
 * When composing an error message, use sentence fragments.
 *
 * Try describing the property of the code that caused the error, rather than
 * the rule that is being violated. It may help to use a fragment that completes
 * a sentence beginning, "the parser encountered (a) ...". If appropriate, add a
 * description of the rule violation (or other helpful context) after a
 * semicolon.
 *
 * For example:, instead of "control escape sequence cannot be doubled", prefer:
 *
 * > "invalid control escape sequence; control cannot be repeated"
 *
 * In some cases, where the failure is more general or syntax expectations are
 * violated, it may make more sense to use a fragment that completes a sentence
 * beginning, "the parser ...".
 *
 * For example:
 *
 * > "expected an expression after `(`"
 * > "cannot parse the expression"
 *
 * ## Message style guide
 *
 * - Use articles like "a", "an", and "the" when appropriate.
 *   - e.g., prefer "cannot parse the expression" to "cannot parse expression".
 * - Use the common name for tokens and nodes.
 *   - e.g., prefer "keyword splat" to "assoc splat"
 *   - e.g., prefer "embedded document" to "embdoc"
 * - Do not capitalize the initial word of the message.
 * - Use back ticks around token literals
 *   - e.g., "Expected a `=>` between the hash key and value"
 * - Do not use `.` or other punctuation at the end of the message.
 * - Do not use contractions like "can't". Prefer "cannot" to "can not".
 * - For tokens that can have multiple meanings, reference the token and its meaning.
 *   - e.g., "`*` splat argument" is clearer and more complete than "splat argument" or "`*` argument"
 *
 * ## Error names (PM_ERR_*)
 *
 * - When appropriate, prefer node name to token name.
 *   - e.g., prefer "SPLAT" to "STAR" in the context of argument parsing.
 * - Prefer token name to common name.
 *   - e.g., prefer "STAR" to "ASTERISK".
 * - Try to order the words in the name from more general to more specific,
 *   - e.g., "INVALID_NUMBER_DECIMAL" is better than "DECIMAL_INVALID_NUMBER".
 *   - When in doubt, look for similar patterns and name them so that they are grouped when lexically
 *     sorted. See PM_ERR_ARGUMENT_NO_FORWARDING_* for an example.
 *
 * ## Level
 *
 * For errors, they are:
 *
 * * `PM_ERROR_LEVEL_FATAL` - The default level for errors.
 * * `PM_ERROR_LEVEL_ARGUMENT` - Errors that should raise ArgumentError.
 *
 * For warnings, they are:
 *
 * * `PM_WARNING_LEVEL_DEFAULT` - Warnings that appear for `ruby -c -e 'code'`.
 * * `PM_WARNING_LEVEL_VERBOSE` - Warnings that appear with `-w`, as in `ruby -w -c -e 'code'`.
 */
static const pm_diagnostic_data_t diagnostic_messages[PM_DIAGNOSTIC_ID_LEN] = {
    // Special error that can be replaced
    [PM_ERR_CANNOT_PARSE_EXPRESSION]            = { "cannot parse the expression", PM_ERROR_LEVEL_FATAL },

    // Errors that should raise argument errors
    [PM_ERR_INVALID_ENCODING_MAGIC_COMMENT]     = { "unknown or invalid encoding in the magic comment", PM_ERROR_LEVEL_ARGUMENT },

    // Errors that should raise syntax errors
    [PM_ERR_ALIAS_ARGUMENT]                     = { "invalid argument being passed to `alias`; expected a bare word, symbol, constant, or global variable", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_AMPAMPEQ_MULTI_ASSIGN]              = { "unexpected `&&=` in a multiple assignment", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_AFTER_BLOCK]               = { "unexpected argument after a block argument", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_AFTER_FORWARDING_ELLIPSES] = { "unexpected argument after `...`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_BARE_HASH]                 = { "unexpected bare hash argument", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_BLOCK_FORWARDING]          = { "both a block argument and a forwarding argument; only one block is allowed", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_BLOCK_MULTI]               = { "multiple block arguments; only one block is allowed", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_FORMAL_CLASS]              = { "invalid formal argument; formal argument cannot be a class variable", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_FORMAL_CONSTANT]           = { "invalid formal argument; formal argument cannot be a constant", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_FORMAL_GLOBAL]             = { "invalid formal argument; formal argument cannot be a global variable", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_FORMAL_IVAR]               = { "invalid formal argument; formal argument cannot be an instance variable", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_FORWARDING_UNBOUND]        = { "unexpected `...` in an non-parenthesized call", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_IN]                        = { "unexpected `in` keyword in arguments", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_NO_FORWARDING_AMP]         = { "unexpected `&` when the parent method is not forwarding", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_NO_FORWARDING_ELLIPSES]    = { "unexpected `...` when the parent method is not forwarding", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_NO_FORWARDING_STAR]        = { "unexpected `*` when the parent method is not forwarding", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_SPLAT_AFTER_ASSOC_SPLAT]   = { "unexpected `*` splat argument after a `**` keyword splat argument", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_SPLAT_AFTER_SPLAT]         = { "unexpected `*` splat argument after a `*` splat argument", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_TERM_PAREN]                = { "expected a `)` to close the arguments", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARGUMENT_UNEXPECTED_BLOCK]          = { "unexpected `{` after a method call without parenthesis", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARRAY_ELEMENT]                      = { "expected an element for the array", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARRAY_EXPRESSION]                   = { "expected an expression for the array element", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARRAY_EXPRESSION_AFTER_STAR]        = { "expected an expression after `*` in the array", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARRAY_SEPARATOR]                    = { "expected a `,` separator for the array elements", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ARRAY_TERM]                         = { "expected a `]` to close the array", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BEGIN_LONELY_ELSE]                  = { "unexpected `else` in `begin` block; a `rescue` clause must precede `else`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BEGIN_TERM]                         = { "expected an `end` to close the `begin` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BEGIN_UPCASE_BRACE]                 = { "expected a `{` after `BEGIN`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BEGIN_UPCASE_TERM]                  = { "expected a `}` to close the `BEGIN` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BEGIN_UPCASE_TOPLEVEL]              = { "BEGIN is permitted only at toplevel", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BLOCK_PARAM_LOCAL_VARIABLE]         = { "expected a local variable name in the block parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BLOCK_PARAM_PIPE_TERM]              = { "expected the block parameters to end with `|`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BLOCK_TERM_BRACE]                   = { "expected a block beginning with `{` to end with `}`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_BLOCK_TERM_END]                     = { "expected a block beginning with `do` to end with `end`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CANNOT_PARSE_STRING_PART]           = { "cannot parse the string part", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CASE_EXPRESSION_AFTER_CASE]         = { "expected an expression after `case`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CASE_EXPRESSION_AFTER_WHEN]         = { "expected an expression after `when`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CASE_MATCH_MISSING_PREDICATE]       = { "expected a predicate for a case matching statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CASE_MISSING_CONDITIONS]            = { "expected a `when` or `in` clause after `case`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CASE_TERM]                          = { "expected an `end` to close the `case` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CLASS_IN_METHOD]                    = { "unexpected class definition in a method definition", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CLASS_NAME]                         = { "expected a constant name after `class`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CLASS_SUPERCLASS]                   = { "expected a superclass after `<`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CLASS_TERM]                         = { "expected an `end` to close the `class` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CLASS_UNEXPECTED_END]               = { "unexpected `end`, expecting ';' or '\\n'", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_ELSIF_PREDICATE]        = { "expected a predicate expression for the `elsif` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_IF_PREDICATE]           = { "expected a predicate expression for the `if` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_PREDICATE_TERM]         = { "expected `then` or `;` or '\\n'", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_TERM]                   = { "expected an `end` to close the conditional clause", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_TERM_ELSE]              = { "expected an `end` to close the `else` clause", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_UNLESS_PREDICATE]       = { "expected a predicate expression for the `unless` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_UNTIL_PREDICATE]        = { "expected a predicate expression for the `until` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONDITIONAL_WHILE_PREDICATE]        = { "expected a predicate expression for the `while` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_CONSTANT_PATH_COLON_COLON_CONSTANT] = { "expected a constant after the `::` operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_ENDLESS]                        = { "could not parse the endless method body", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_ENDLESS_SETTER]                 = { "invalid method name; a setter method cannot be defined in an endless method definition", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_NAME]                           = { "expected a method name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_NAME_AFTER_RECEIVER]            = { "expected a method name after the receiver", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_PARAMS_TERM]                    = { "expected a delimiter to close the parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_PARAMS_TERM_PAREN]              = { "expected a `)` to close the parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_RECEIVER]                       = { "expected a receiver for the method definition", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_RECEIVER_TERM]                  = { "expected a `.` or `::` after the receiver in a method definition", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEF_TERM]                           = { "expected an `end` to close the `def` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_DEFINED_EXPRESSION]                 = { "expected an expression after `defined?`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EMBDOC_TERM]                        = { "could not find a terminator for the embedded document", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EMBEXPR_END]                        = { "expected a `}` to close the embedded expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EMBVAR_INVALID]                     = { "invalid embedded variable", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_END_UPCASE_BRACE]                   = { "expected a `{` after `END`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_END_UPCASE_TERM]                    = { "expected a `}` to close the `END` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_CONTROL]             = { "invalid control escape sequence", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_CONTROL_REPEAT]      = { "invalid control escape sequence; control cannot be repeated", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_HEXADECIMAL]         = { "invalid hexadecimal escape sequence", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_META]                = { "invalid meta escape sequence", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_META_REPEAT]         = { "invalid meta escape sequence; meta cannot be repeated", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_UNICODE]             = { "invalid Unicode escape sequence", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_UNICODE_CM_FLAGS]    = { "invalid Unicode escape sequence; Unicode cannot be combined with control or meta flags", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_UNICODE_LITERAL]     = { "invalid Unicode escape sequence; multiple codepoints are not allowed in a character literal", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_UNICODE_LONG]        = { "invalid Unicode escape sequence; maximum length is 6 digits", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_ESCAPE_INVALID_UNICODE_TERM]        = { "invalid Unicode escape sequence; needs closing `}`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_ARGUMENT]                    = { "expected an argument", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EOL_AFTER_STATEMENT]         = { "unexpected %s, expecting end-of-input", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_AMPAMPEQ]   = { "expected an expression after `&&=`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_PIPEPIPEEQ] = { "expected an expression after `||=`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_COMMA]      = { "expected an expression after `,`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_EQUAL]      = { "expected an expression after `=`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_LESS_LESS]  = { "expected an expression after `<<`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_LPAREN]     = { "expected an expression after `(`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_OPERATOR]   = { "expected an expression after the operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_SPLAT]      = { "expected an expression after `*` splat in an argument", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_SPLAT_HASH] = { "expected an expression after `**` in a hash", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_EXPRESSION_AFTER_STAR]       = { "expected an expression after `*`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_IDENT_REQ_PARAMETER]         = { "expected an identifier for the required parameter", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_LPAREN_REQ_PARAMETER]        = { "expected a `(` to start a required parameter", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_RBRACKET]                    = { "expected a matching `]`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_RPAREN]                      = { "expected a matching `)`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_RPAREN_AFTER_MULTI]          = { "expected a `)` after multiple assignment", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_RPAREN_REQ_PARAMETER]        = { "expected a `)` to end a required parameter", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_STRING_CONTENT]              = { "expected string content after opening string delimiter", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPECT_WHEN_DELIMITER]              = { "expected a delimiter after the predicates of a `when` clause", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_EXPRESSION_BARE_HASH]               = { "unexpected bare hash in expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_FOR_COLLECTION]                     = { "expected a collection after the `in` in a `for` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_FOR_INDEX]                          = { "expected an index after `for`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_FOR_IN]                             = { "expected an `in` after the index in a `for` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_FOR_TERM]                           = { "expected an `end` to close the `for` loop", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_HASH_EXPRESSION_AFTER_LABEL]        = { "expected an expression after the label in a hash", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_HASH_KEY]                           = { "unexpected %s, expecting '}' or a key in the hash literal", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_HASH_ROCKET]                        = { "expected a `=>` between the hash key and value", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_HASH_TERM]                          = { "expected a `}` to close the hash literal", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_HASH_VALUE]                         = { "expected a value in the hash literal", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_HEREDOC_TERM]                       = { "could not find a terminator for the heredoc", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INCOMPLETE_QUESTION_MARK]           = { "incomplete expression at `?`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INCOMPLETE_VARIABLE_CLASS_3_3_0]    = { "`%.*s' is not allowed as a class variable name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INCOMPLETE_VARIABLE_CLASS]          = { "'%.*s' is not allowed as a class variable name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INCOMPLETE_VARIABLE_INSTANCE_3_3_0] = { "`%.*s' is not allowed as an instance variable name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INCOMPLETE_VARIABLE_INSTANCE]       = { "'%.*s' is not allowed as an instance variable name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_FLOAT_EXPONENT]             = { "invalid exponent", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_NUMBER_BINARY]              = { "invalid binary number", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_NUMBER_DECIMAL]             = { "invalid decimal number", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_NUMBER_HEXADECIMAL]         = { "invalid hexadecimal number", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_NUMBER_OCTAL]               = { "invalid octal number", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_NUMBER_UNDERSCORE]          = { "invalid underscore placement in number", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_CHARACTER]                  = { "invalid character 0x%X", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_MULTIBYTE_CHARACTER]        = { "invalid multibyte character 0x%X", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_PRINTABLE_CHARACTER]        = { "invalid character `%c`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_PERCENT]                    = { "invalid `%` token", PM_ERROR_LEVEL_FATAL }, // TODO WHAT?
    [PM_ERR_INVALID_VARIABLE_GLOBAL_3_3_0]      = { "`%.*s' is not allowed as a global variable name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_INVALID_VARIABLE_GLOBAL]            = { "'%.*s' is not allowed as a global variable name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_IT_NOT_ALLOWED_NUMBERED]            = { "`it` is not allowed when an numbered parameter is defined", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_IT_NOT_ALLOWED_ORDINARY]            = { "`it` is not allowed when an ordinary parameter is defined", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LAMBDA_OPEN]                        = { "expected a `do` keyword or a `{` to open the lambda block", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LAMBDA_TERM_BRACE]                  = { "expected a lambda block beginning with `{` to end with `}`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LAMBDA_TERM_END]                    = { "expected a lambda block beginning with `do` to end with `end`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_I_LOWER_ELEMENT]               = { "expected a symbol in a `%i` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_I_LOWER_TERM]                  = { "expected a closing delimiter for the `%i` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_I_UPPER_ELEMENT]               = { "expected a symbol in a `%I` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_I_UPPER_TERM]                  = { "expected a closing delimiter for the `%I` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_W_LOWER_ELEMENT]               = { "expected a string in a `%w` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_W_LOWER_TERM]                  = { "expected a closing delimiter for the `%w` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_W_UPPER_ELEMENT]               = { "expected a string in a `%W` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_LIST_W_UPPER_TERM]                  = { "expected a closing delimiter for the `%W` list", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_MALLOC_FAILED]                      = { "failed to allocate memory", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_MIXED_ENCODING]                     = { "UTF-8 mixed within %s source", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_MODULE_IN_METHOD]                   = { "unexpected module definition in a method definition", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_MODULE_NAME]                        = { "expected a constant name after `module`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_MODULE_TERM]                        = { "expected an `end` to close the `module` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_MULTI_ASSIGN_MULTI_SPLATS]          = { "multiple splats in multiple assignment", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_MULTI_ASSIGN_UNEXPECTED_REST]       = { "unexpected '%.*s' resulting in multiple splats in multiple assignment", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_NOT_EXPRESSION]                     = { "expected an expression after `not`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_NO_LOCAL_VARIABLE]                  = { "%.*s: no such local variable", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_NUMBER_LITERAL_UNDERSCORE]          = { "number literal ending with a `_`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_NUMBERED_PARAMETER_IT]              = { "numbered parameters are not allowed when an 'it' parameter is defined", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_NUMBERED_PARAMETER_ORDINARY]        = { "numbered parameters are not allowed when an ordinary parameter is defined", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_NUMBERED_PARAMETER_OUTER_SCOPE]     = { "numbered parameter is already used in outer scope", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_OPERATOR_MULTI_ASSIGN]              = { "unexpected operator for a multiple assignment", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_OPERATOR_WRITE_ARGUMENTS]           = { "unexpected operator after a call with arguments", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_OPERATOR_WRITE_BLOCK]               = { "unexpected operator after a call with a block", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_ASSOC_SPLAT_MULTI]        = { "unexpected multiple `**` splat parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_BLOCK_MULTI]              = { "multiple block parameters; only one block is allowed", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_CIRCULAR]                 = { "parameter default value references itself", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_METHOD_NAME]              = { "unexpected name for a parameter", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_NAME_REPEAT]              = { "repeated parameter name", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_NO_DEFAULT]               = { "expected a default value for the parameter", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_NO_DEFAULT_KW]            = { "expected a default value for the keyword parameter", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_NUMBERED_RESERVED]        = { "%.2s is reserved for numbered parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_ORDER]                    = { "unexpected parameter order", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_SPLAT_MULTI]              = { "unexpected multiple `*` splat parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_STAR]                     = { "unexpected parameter `*`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_UNEXPECTED_FWD]           = { "unexpected `...` in parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PARAMETER_WILD_LOOSE_COMMA]         = { "unexpected `,` in parameters", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_BRACKET]   = { "expected a pattern expression after the `[` operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_COMMA]     = { "expected a pattern expression after `,`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_HROCKET]   = { "expected a pattern expression after `=>`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_IN]        = { "expected a pattern expression after the `in` keyword", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_KEY]       = { "expected a pattern expression after the key", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_PAREN]     = { "expected a pattern expression after the `(` operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_PIN]       = { "expected a pattern expression after the `^` pin operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_PIPE]      = { "expected a pattern expression after the `|` operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_RANGE]     = { "expected a pattern expression after the range operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_EXPRESSION_AFTER_REST]      = { "unexpected pattern expression after the `**` expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_HASH_KEY]                   = { "expected a key in the hash pattern", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_HASH_KEY_LABEL]             = { "expected a label as the key in the hash pattern", PM_ERROR_LEVEL_FATAL }, // TODO // THIS // AND // ABOVE // IS WEIRD
    [PM_ERR_PATTERN_IDENT_AFTER_HROCKET]        = { "expected an identifier after the `=>` operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_LABEL_AFTER_COMMA]          = { "expected a label after the `,` in the hash pattern", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_REST]                       = { "unexpected rest pattern", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_TERM_BRACE]                 = { "expected a `}` to close the pattern expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_TERM_BRACKET]               = { "expected a `]` to close the pattern expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PATTERN_TERM_PAREN]                 = { "expected a `)` to close the pattern expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_PIPEPIPEEQ_MULTI_ASSIGN]            = { "unexpected `||=` in a multiple assignment", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_REGEXP_TERM]                        = { "expected a closing delimiter for the regular expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_RESCUE_EXPRESSION]                  = { "expected a rescued expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_RESCUE_MODIFIER_VALUE]              = { "expected a value after the `rescue` modifier", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_RESCUE_TERM]                        = { "expected a closing delimiter for the `rescue` clause", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_RESCUE_VARIABLE]                    = { "expected an exception variable after `=>` in a rescue statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_RETURN_INVALID]                     = { "invalid `return` in a class or module body", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_SINGLETON_FOR_LITERALS]             = { "cannot define singleton method for literals", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STATEMENT_ALIAS]                    = { "unexpected an `alias` at a non-statement position", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STATEMENT_POSTEXE_END]              = { "unexpected an `END` at a non-statement position", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STATEMENT_PREEXE_BEGIN]             = { "unexpected a `BEGIN` at a non-statement position", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STATEMENT_UNDEF]                    = { "unexpected an `undef` at a non-statement position", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STRING_CONCATENATION]               = { "expected a string for concatenation", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STRING_INTERPOLATED_TERM]           = { "expected a closing delimiter for the interpolated string", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STRING_LITERAL_EOF]                 = { "unterminated string meets end of file", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_STRING_LITERAL_TERM]                = { "unexpected %s, expected a string literal terminator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_SYMBOL_INVALID]                     = { "invalid symbol", PM_ERROR_LEVEL_FATAL }, // TODO expected symbol? prism.c ~9719
    [PM_ERR_SYMBOL_TERM_DYNAMIC]                = { "expected a closing delimiter for the dynamic symbol", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_SYMBOL_TERM_INTERPOLATED]           = { "expected a closing delimiter for the interpolated symbol", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_TERNARY_COLON]                      = { "expected a `:` after the true expression of a ternary operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_TERNARY_EXPRESSION_FALSE]           = { "expected an expression after `:` in the ternary operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_TERNARY_EXPRESSION_TRUE]            = { "expected an expression after `?` in the ternary operator", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_UNDEF_ARGUMENT]                     = { "invalid argument being passed to `undef`; expected a bare word, constant, or symbol argument", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_UNARY_RECEIVER]                     = { "unexpected %s, expected a receiver for unary `%c`", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_UNEXPECTED_TOKEN_CLOSE_CONTEXT]     = { "unexpected %s, assuming it is closing the parent %s", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_UNEXPECTED_TOKEN_IGNORE]            = { "unexpected %s, ignoring it", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_UNTIL_TERM]                         = { "expected an `end` to close the `until` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_VOID_EXPRESSION]                    = { "unexpected void value expression", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_WHILE_TERM]                         = { "expected an `end` to close the `while` statement", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_WRITE_TARGET_IN_METHOD]             = { "dynamic constant assignment", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_WRITE_TARGET_READONLY]              = { "Can't set variable %.*s", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_WRITE_TARGET_UNEXPECTED]            = { "unexpected write target", PM_ERROR_LEVEL_FATAL },
    [PM_ERR_XSTRING_TERM]                       = { "expected a closing delimiter for the `%x` or backtick string", PM_ERROR_LEVEL_FATAL },

    // Warnings
    [PM_WARN_AMBIGUOUS_FIRST_ARGUMENT_MINUS]    = { "ambiguous first argument; put parentheses or a space even after `-` operator", PM_WARNING_LEVEL_VERBOSE },
    [PM_WARN_AMBIGUOUS_FIRST_ARGUMENT_PLUS]     = { "ambiguous first argument; put parentheses or a space even after `+` operator", PM_WARNING_LEVEL_VERBOSE },
    [PM_WARN_AMBIGUOUS_PREFIX_STAR]             = { "ambiguous `*` has been interpreted as an argument prefix", PM_WARNING_LEVEL_VERBOSE },
    [PM_WARN_AMBIGUOUS_SLASH]                   = { "ambiguous `/`; wrap regexp in parentheses or add a space after `/` operator", PM_WARNING_LEVEL_VERBOSE },
    [PM_WARN_EQUAL_IN_CONDITIONAL]              = { "found `= literal' in conditional, should be ==", PM_WARNING_LEVEL_DEFAULT },
    [PM_WARN_END_IN_METHOD]                     = { "END in method; use at_exit", PM_WARNING_LEVEL_DEFAULT },
};

static inline const char *
pm_diagnostic_message(pm_diagnostic_id_t diag_id) {
    assert(diag_id < PM_DIAGNOSTIC_ID_LEN);

    const char *message = diagnostic_messages[diag_id].message;
    assert(message);

    return message;
}

static inline uint8_t
pm_diagnostic_level(pm_diagnostic_id_t diag_id) {
    assert(diag_id < PM_DIAGNOSTIC_ID_LEN);

    return (uint8_t) diagnostic_messages[diag_id].level;
}

/**
 * Append an error to the given list of diagnostic.
 */
bool
pm_diagnostic_list_append(pm_list_t *list, const uint8_t *start, const uint8_t *end, pm_diagnostic_id_t diag_id) {
    pm_diagnostic_t *diagnostic = (pm_diagnostic_t *) calloc(sizeof(pm_diagnostic_t), 1);
    if (diagnostic == NULL) return false;

    *diagnostic = (pm_diagnostic_t) {
        .location = { start, end },
        .message = pm_diagnostic_message(diag_id),
        .owned = false,
        .level = pm_diagnostic_level(diag_id)
    };

    pm_list_append(list, (pm_list_node_t *) diagnostic);
    return true;
}

/**
 * Append a diagnostic to the given list of diagnostics that is using a format
 * string for its message.
 */
bool
pm_diagnostic_list_append_format(pm_list_t *list, const uint8_t *start, const uint8_t *end, pm_diagnostic_id_t diag_id, ...) {
    va_list arguments;
    va_start(arguments, diag_id);

    const char *format = pm_diagnostic_message(diag_id);
    int result = vsnprintf(NULL, 0, format, arguments);
    va_end(arguments);

    if (result < 0) {
        return false;
    }

    pm_diagnostic_t *diagnostic = (pm_diagnostic_t *) calloc(sizeof(pm_diagnostic_t), 1);
    if (diagnostic == NULL) {
        return false;
    }

    size_t length = (size_t) (result + 1);
    char *message = (char *) malloc(length);
    if (message == NULL) {
        free(diagnostic);
        return false;
    }

    va_start(arguments, diag_id);
    vsnprintf(message, length, format, arguments);
    va_end(arguments);

    *diagnostic = (pm_diagnostic_t) {
        .location = { start, end },
        .message = message,
        .owned = true,
        .level = pm_diagnostic_level(diag_id)
    };

    pm_list_append(list, (pm_list_node_t *) diagnostic);
    return true;
}

/**
 * Deallocate the internal state of the given diagnostic list.
 */
void
pm_diagnostic_list_free(pm_list_t *list) {
    pm_diagnostic_t *node = (pm_diagnostic_t *) list->head;

    while (node != NULL) {
        pm_diagnostic_t *next = (pm_diagnostic_t *) node->node.next;

        if (node->owned) free((void *) node->message);
        free(node);

        node = next;
    }
}