Make iconv //IGNORE behavior conform to POSIX and the docs

ext/iconv/config.m4

@@ -83,34 +83,6 @@ int main(void) {
   AS_VAR_IF([php_cv_iconv_errno], [yes],,
     [AC_MSG_FAILURE([The iconv check failed, 'errno' is missing.])])
 
-  AC_CACHE_CHECK([if iconv supports //IGNORE], [php_cv_iconv_ignore],
-    [AC_RUN_IFELSE([AC_LANG_SOURCE([
-#include <iconv.h>
-#include <stdlib.h>
-
-int main(void) {
-  iconv_t cd = iconv_open( "UTF-8//IGNORE", "UTF-8" );
-  if(cd == (iconv_t)-1) {
-    return 1;
-  }
-  char *in_p = "\xC3\xC3\xC3\xB8";
-  size_t in_left = 4, out_left = 4096;
-  char *out = malloc(out_left);
-  char *out_p = out;
-  size_t result = iconv(cd, (char **) &in_p, &in_left, (char **) &out_p, &out_left);
-  if(result == (size_t)-1) {
-    return 1;
-  }
-  return 0;
-}
-    ])],
-    [php_cv_iconv_ignore=yes],
-    [php_cv_iconv_ignore=no],
-    [php_cv_iconv_ignore=no])])
-  AS_VAR_IF([php_cv_iconv_ignore], [no],
-    [AC_DEFINE([ICONV_BROKEN_IGNORE], [1],
-      [Define to 1 if iconv has broken IGNORE.])])
-
   LIBS=$save_LIBS
   CFLAGS=$save_CFLAGS
 

ext/iconv/iconv.c

@@ -415,24 +415,6 @@ static php_iconv_err_t _php_iconv_appendc(smart_str *d, const char c, iconv_t cd
 }
 /* }}} */
 
-/* {{{ */
-#ifdef ICONV_BROKEN_IGNORE
-static int _php_check_ignore(const char *charset)
-{
-	size_t clen = strlen(charset);
-	if (clen >= 9 && strcmp("//IGNORE", charset+clen-8) == 0) {
-		return 1;
-	}
-	if (clen >= 19 && strcmp("//IGNORE//TRANSLIT", charset+clen-18) == 0) {
-		return 1;
-	}
-	return 0;
-}
-#else
-#define _php_check_ignore(x) (0)
-#endif
-/* }}} */
-
 /* {{{ php_iconv_string() */
 PHP_ICONV_API php_iconv_err_t php_iconv_string(const char *in_p, size_t in_len, zend_string **out, const char *out_charset, const char *in_charset)
 {
@@ -442,7 +424,6 @@ PHP_ICONV_API php_iconv_err_t php_iconv_string(const char *in_p, size_t in_len,
 	size_t bsz, result = 0;
 	php_iconv_err_t retval = PHP_ICONV_ERR_SUCCESS;
 	zend_string *out_buf;
-	int ignore_ilseq = _php_check_ignore(out_charset);
 
 	*out = NULL;
 
@@ -466,16 +447,6 @@ PHP_ICONV_API php_iconv_err_t php_iconv_string(const char *in_p, size_t in_len,
 		result = iconv(cd, (ICONV_CONST char **) &in_p, &in_left, (char **) &out_p, &out_left);
 		out_size = bsz - out_left;
 		if (result == (size_t)(-1)) {
-			if (ignore_ilseq && errno == EILSEQ) {
-				if (in_left <= 1) {
-					result = 0;
-				} else {
-					errno = 0;
-					in_p++;
-					in_left--;
-					continue;
-				}
-			}
 
 			if (errno == E2BIG && in_left > 0) {
 				/* converted string is longer than out buffer */

ext/iconv/tests/dont-ignore-invalid-inputs.phpt

@@ -0,0 +1,42 @@
+--TEST--
+iconv with //IGNORE should not ignore invalid input sequences
+--EXTENSIONS--
+iconv
+--SKIPIF--
+<?php
+// POSIX 2024 standardizes "//IGNORE", but some implementations (like musl)
+// do not support it yet. If iconv() doesn't understand "//IGNORE", the
+// tests below will still fail, but you'll get an error message about
+// finding an unexpected string in your encoding name rather than the
+// expected illegal-sequence error.
+if (ICONV_IMPL == "unknown") {
+    die("skip iconv implementation may not understand //IGNORE");
+}
+?>
+--FILE--
+<?php
+$text = "aa\xC3\xC3\xC3\xB8aa";
+var_dump(iconv("UTF-8", "UTF-8", $text));
+var_dump(iconv("UTF-8", "UTF-8//IGNORE", $text));
+// only invalid
+var_dump(iconv("UTF-8", "UTF-8//IGNORE", "\xC3"));
+// start invalid
+var_dump(iconv("UTF-8", "UTF-8//IGNORE", "\xC3\xC3\xC3\xB8aa"));
+// finish invalid
+var_dump(iconv("UTF-8", "UTF-8//IGNORE", "aa\xC3\xC3\xC3"));
+?>
+--EXPECTF--
+Notice: iconv(): Detected an illegal character in input string in %s on line %d
+bool(false)
+
+Notice: iconv(): Detected an illegal character in input string in %s on line %d
+bool(false)
+
+Notice: iconv(): Detected an incomplete multibyte character in input string in %s on line %d
+bool(false)
+
+Notice: iconv(): Detected an illegal character in input string in %s on line %d
+bool(false)
+
+Notice: iconv(): Detected an incomplete multibyte character in input string in %s on line %d
+bool(false)