C++: Fix range analysis bug for 'RemExpr'.

Author: MathiasVP

cpp/ql/src/semmle/code/cpp/rangeanalysis/SimpleRangeAnalysis.qll

@@ -1064,7 +1064,7 @@ private float getUpperBoundsImpl(Expr expr) {
       // absolute value. Since `abs(x) = max(-x,x)` this is equivalent to
       // adding `-rhsLB` to the set of upper bounds.
       exists(float rhsLB |
-        rhsLB = getFullyConvertedLowerBounds(remExpr.getAnOperand()) and
+        rhsLB = getFullyConvertedLowerBounds(remExpr.getRightOperand()) and
         not rhsLB >= 0
       |
         result = -rhsLB

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/lowerBound.expected

@@ -593,7 +593,7 @@
 | test.c:658:7:658:7 | u | 0 |
 | test.c:659:9:659:9 | u | 0 |
 | test.c:664:12:664:12 | s | -2147483648 |
-| test.c:665:7:665:8 | s2 | -2147483648 |
+| test.c:665:7:665:8 | s2 | -5 |
 | test.cpp:10:7:10:7 | b | -2147483648 |
 | test.cpp:11:5:11:5 | x | -2147483648 |
 | test.cpp:13:10:13:10 | x | -2147483648 |

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/test.c

@@ -662,5 +662,5 @@ void guard_bound_out_of_range(void) {
 
 void test_mod(int s) {
   int s2 = s % 5;
-  out(s2); // -4 .. 4 [BUG: is -max .. max]
+  out(s2); // -4 .. 4 [BUG: is -5 .. 5]
 }

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/upperBound.expected

@@ -593,7 +593,7 @@
 | test.c:658:7:658:7 | u | 0 |
 | test.c:659:9:659:9 | u | 4294967295 |
 | test.c:664:12:664:12 | s | 2147483647 |
-| test.c:665:7:665:8 | s2 | 2147483647 |
+| test.c:665:7:665:8 | s2 | 5 |
 | test.cpp:10:7:10:7 | b | 2147483647 |
 | test.cpp:11:5:11:5 | x | 2147483647 |
 | test.cpp:13:10:13:10 | x | 2147483647 |