Drop misleading comments about undefined behavior (GH-17532)

cmb69 · web-flow · commit ab996934ebb9 · 2025-01-26T22:50:52.000+01:00
There is no undefined behavior here.  If `BitScan*()` returns zero, the
value written to the first parameter is undefined, but we return a
reasonable value.
diff --git a/Zend/zend_bitset.h b/Zend/zend_bitset.h
@@ -60,7 +60,6 @@ ZEND_ATTRIBUTE_CONST static zend_always_inline int zend_ulong_ntz(zend_ulong num
 #else
 	if (!BitScanForward(&index, num)) {
 #endif
-		/* undefined behavior */
 		return SIZEOF_ZEND_LONG * 8;
 	}
 
@@ -98,7 +97,6 @@ ZEND_ATTRIBUTE_CONST static zend_always_inline int zend_ulong_nlz(zend_ulong num
 #else
 	if (!BitScanReverse(&index, num)) {
 #endif
-		/* undefined behavior */
 		return SIZEOF_ZEND_LONG * 8;
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -60,7 +60,6 @@ ZEND_ATTRIBUTE_CONST static zend_always_inline int zend_ulong_ntz(zend_ulong num`
`60`	`60`	`#else`
`61`	`61`	`if (!BitScanForward(&index, num)) {`
`62`	`62`	`#endif`
`63`		`- /* undefined behavior */`
`64`	`63`	`return SIZEOF_ZEND_LONG * 8;`
`65`	`64`	`}`
`66`	`65`
`@@ -98,7 +97,6 @@ ZEND_ATTRIBUTE_CONST static zend_always_inline int zend_ulong_nlz(zend_ulong num`
`98`	`97`	`#else`
`99`	`98`	`if (!BitScanReverse(&index, num)) {`
`100`	`99`	`#endif`
`101`		`- /* undefined behavior */`
`102`	`100`	`return SIZEOF_ZEND_LONG * 8;`
`103`	`101`	`}`
`104`	`102`