Add support for %h and %H in printf()

These are locale-independent variants of %g and %G.

Closes phpGH-5436.

Author: nikic

UPGRADING

@@ -535,6 +535,11 @@ PHP 8.0 UPGRADE NOTES
     compile-time warnings and replay them on the next include, even if it is
     served from cache.
 
+- Standard:
+  . printf() and friends how support the %h and %H format specifiers. These
+    are the same as %g and %G, but always use "." as the decimal separator,
+    rather than determining it through the LC_NUMERIC locale.
+
 - Zip:
   . Extension updated to version 1.19.0
   . New ZipArchive::lastId property to get index value of last added entry.

ext/standard/formatted_print.c

@@ -281,17 +281,25 @@ php_sprintf_appenddouble(zend_string **buffer, size_t *pos,
 
 		case 'g':
 		case 'G':
+		case 'h':
+		case 'H':
+		{
 			if (precision == 0)
 				precision = 1;
-			/*
-			 * * We use &num_buf[ 1 ], so that we have room for the sign
-			 */
+
+			char decimal_point = '.';
+			if (fmt == 'g' || fmt == 'G') {
 #ifdef ZTS
-			localeconv_r(&lconv);
+				localeconv_r(&lconv);
 #else
-			lconv = localeconv();
+				lconv = localeconv();
 #endif
-			s = php_gcvt(number, precision, LCONV_DECIMAL_POINT, (fmt == 'G')?'E':'e', &num_buf[1]);
+				decimal_point = LCONV_DECIMAL_POINT;
+			}
+
+			char exp_char = fmt == 'G' || fmt == 'H' ? 'E' : 'e';
+			/* We use &num_buf[ 1 ], so that we have room for the sign. */
+			s = php_gcvt(number, precision, decimal_point, exp_char, &num_buf[1]);
 			is_negative = 0;
 			if (*s == '-') {
 				is_negative = 1;
@@ -303,6 +311,7 @@ php_sprintf_appenddouble(zend_string **buffer, size_t *pos,
 
 			s_len = strlen(s);
 			break;
+		}
 	}
 
 	php_sprintf_appendstring(buffer, pos, s, width, 0, padding,
@@ -562,12 +571,14 @@ php_formatted_print(char *format, size_t format_len, zval *args, int argc, int n
 										  width, padding, alignment);
 					break;
 
-				case 'g':
-				case 'G':
 				case 'e':
 				case 'E':
 				case 'f':
 				case 'F':
+				case 'g':
+				case 'G':
+				case 'h':
+				case 'H':
 					php_sprintf_appenddouble(&result, &outpos,
 											 zval_get_double(tmp),
 											 width, padding, alignment,

ext/standard/tests/strings/printf_h_H.phpt

@@ -0,0 +1,19 @@
+--TEST--
+sprintf() %h and %H specifiers
+--SKIPIF--
+<?php
+if (!setlocale(LC_ALL, "de_DE.utf8")) die("skip de_DE.utf8 locale not available");
+?>
+--FILE--
+<?php
+
+setlocale(LC_ALL, "de_DE.utf8");
+$f = 1.25;
+printf("%g %G %h %H\n", $f, $f, $f, $f);
+$f = 0.00000125;
+printf("%g %G %h %H\n", $f, $f, $f, $f);
+
+?>
+--EXPECT--
+1,25 1,25 1.25 1.25
+1,25e-6 1,25E-6 1.25e-6 1.25E-6