C++: Fix another place that assumed that 'Expr' was always 'Instruction'.

Author: MathiasVP

cpp/ql/test/library-tests/ir/modulus-analysis/ModulusAnalysis.ql

@@ -5,6 +5,7 @@ import experimental.semmle.code.cpp.semantic.analysis.RangeUtils
 import experimental.semmle.code.cpp.semantic.analysis.FloatDelta
 import experimental.semmle.code.cpp.semantic.analysis.RangeAnalysisSpecific
 import experimental.semmle.code.cpp.semantic.analysis.RangeAnalysisImpl
+import experimental.semmle.code.cpp.semantic.SemanticExprSpecific
 import semmle.code.cpp.ir.IR as IR
 import TestUtilities.InlineExpectationsTest
 
@@ -18,7 +19,7 @@ class ModulusAnalysisTest extends InlineExpectationsTest {
 
   override predicate hasActualResult(Location location, string element, string tag, string value) {
     exists(SemExpr e, IR::CallInstruction call |
-      call.getArgument(0) = e and
+      getSemanticExpr(call.getArgument(0)) = e and
       call.getStaticCallTarget().hasName("mod") and
       tag = "mod" and
       element = e.toString() and