Avoid triggering undefined behaviour in base_uint<BITS>::bits()

practicalswift · practicalswift · commit 96f6dc9fc50b · 2018-10-18T11:17:05.000+02:00
diff --git a/src/arith_uint256.cpp b/src/arith_uint256.cpp
@@ -176,7 +176,7 @@ unsigned int base_uint<BITS>::bits() const
     for (int pos = WIDTH - 1; pos >= 0; pos--) {
         if (pn[pos]) {
             for (int nbits = 31; nbits > 0; nbits--) {
-                if (pn[pos] & 1 << nbits)
+                if (pn[pos] & 1U << nbits)
                     return 32 * pos + nbits + 1;
             }
             return 32 * pos + 1;

Original file line number	Diff line number	Diff line change
`@@ -176,7 +176,7 @@ unsigned int base_uint<BITS>::bits() const`
`176`	`176`	`for (int pos = WIDTH - 1; pos >= 0; pos--) {`
`177`	`177`	`if (pn[pos]) {`
`178`	`178`	`for (int nbits = 31; nbits > 0; nbits--) {`
`179`		`- if (pn[pos] & 1 << nbits)`
	`179`	`+ if (pn[pos] & 1U << nbits)`
`180`	`180`	`return 32 * pos + nbits + 1;`
`181`	`181`	`}`
`182`	`182`	`return 32 * pos + 1;`