[jeff-grimes-pplx]

Problem

json_parse_string_with_comments() (and therefore json_parse_file_with_comments()) silently drops data or fails to parse valid commented JSON when a line comment contains /* or a lone ".

const char *s =
    "{\n"
    "  \"a\": 1, // matches src/*.c\n"
    "  \"b\": 2, /* required */\n"
    "  \"c\": 3\n"
    "}";
JSON_Value *v = json_parse_string_with_comments(s);
/* expected {"a":1,"b":2,"c":3}, actual {"a":1,"c":3} -- "b" is silently lost */

A line comment with an unmatched quote (// 5" screen) followed by a block comment makes the whole document fail to parse (NULL).

Root Cause

Comments are stripped by two independent passes:

remove_comments(string_mutable_copy, "/*", "*/");
remove_comments(string_mutable_copy, "//", "\n");

Each pass only knows about string literals and its own comment style. During the /* */ pass, the /* inside // matches src/*.c is treated as the start of a block comment, which then runs until the */ of the next comment, blanking out the "b": 2, member in between. Likewise, a " inside a line comment flips the block pass's in_string state, so the following /* px */ is never removed and the parser sees garbage.

Fix

Replace the two passes with a single left-to-right pass that tracks string literals (including escapes), /* ... */ comments and // ... comments at the same time, so whichever construct opens first wins — exactly as a C/JS lexer would. Behaviour for every input that previously worked is unchanged: comment bodies are still overwritten with spaces, the newline that ends a line comment is preserved, and an unterminated block comment still blanks to the end of the input.

Minimal Reproducer

Compiling and running the snippet above under ASan/UBSan:

gcc -std=c89 -Wall -Wextra -fsanitize=address,undefined -g -I. repro.c parson.c -o repro && ./repro

Before: [FAIL] line comment containing '/*' must not swallow data (actual {"a":1,"c":3}) and [FAIL] line comment containing a lone '"' must not hide a block comment (actual NULL). After: all cases pass.

Verification

• New test_suite_2_mixed_comments() in tests.c (4 cases) — fails on master (Tests failed: 4), passes with the fix.
• make test, make testcpp, make test_hash_collisions: Tests failed: 0, Tests passed: 369 each.