ONLY static cast when we are comparing to a collection.size()

Author: sbaluja

tools/code-generation/smithy/cpp-codegen/smithy-cpp-codegen/src/main/java/com/amazonaws/util/awsclientsmithygenerator/generators/waiters/jmespath/ComparatorEmitter.java

@@ -54,6 +54,15 @@ public String visitComparator(ComparatorExpression expression) {
             case NOT_EQUAL: op = " != "; break;
             default: throw new UnsupportedOperationException("Unsupported comparator: " + expression.getComparator());
         }
+        left = castCountIfForSizeComparison(left, right);
+        right = castCountIfForSizeComparison(right, left);
         return "(" + left + op + right + ")";
     }
+
+    static String castCountIfForSizeComparison(String operand, String other) {
+        if (operand.contains("std::count_if") && other.contains(".size()")) {
+            return "static_cast<std::size_t>(" + operand + ")";
+        }
+        return operand;
+    }
 }

tools/code-generation/smithy/cpp-codegen/smithy-cpp-codegen/src/main/java/com/amazonaws/util/awsclientsmithygenerator/generators/waiters/jmespath/FilterOperandEmitter.java

@@ -98,8 +98,8 @@ private String emitItemCountIf(FilterProjectionExpression filterExpr) {
 
         String predicate = filterExpr.getComparison().accept(
             new FilterPredicateEmitter("inner", model, innerElementShape, smithyServiceName));
-        return "static_cast<std::size_t>(std::count_if(" + collection + ".begin(), " + collection + ".end(), "
-                + "[](const " + innerElementType + "& inner) { return " + predicate + "; }))";
+        return "std::count_if(" + collection + ".begin(), " + collection + ".end(), "
+                + "[](const " + innerElementType + "& inner) { return " + predicate + "; })";
     }
 
     private String resolveInnerElementType(JmespathExpression collectionExpr) {

tools/code-generation/smithy/cpp-codegen/smithy-cpp-codegen/src/main/java/com/amazonaws/util/awsclientsmithygenerator/generators/waiters/jmespath/FilterPredicateEmitter.java

@@ -67,6 +67,8 @@ public String visitComparator(ComparatorExpression expression) {
             case NOT_EQUAL: op = " != "; break;
             default: throw new UnsupportedOperationException("Unsupported comparator: " + expression.getComparator());
         }
+        left = ComparatorEmitter.castCountIfForSizeComparison(left, right);
+        right = ComparatorEmitter.castCountIfForSizeComparison(right, left);
         return "(" + left + op + right + ")";
     }
 }

tools/code-generation/smithy/cpp-codegen/smithy-cpp-codegen/src/main/java/com/amazonaws/util/awsclientsmithygenerator/generators/waiters/jmespath/ScalarEmitter.java

@@ -43,7 +43,7 @@ public String visitFunction(FunctionExpression expression) {
         if ("length".equals(expression.getName())) {
             JmespathExpression arg = expression.getArguments().get(0);
             if (arg instanceof FilterProjectionExpression) {
-                return emitCountIf((FilterProjectionExpression) arg);
+                return  emitCountIf((FilterProjectionExpression) arg);
             }
             String collection = arg.accept(new CollectionGetterEmitter());
             return "result" + collection + ".size()";
@@ -65,8 +65,8 @@ private String emitCountIf(FilterProjectionExpression filterExpr) {
 
         String predicate = filterExpr.getComparison().accept(
             new FilterPredicateEmitter("item", model, elementShape, smithyServiceName));
-        return "static_cast<std::size_t>(std::count_if(" + collection + ".begin(), " + collection + ".end(), "
-                + "[](const " + elementType + "& item) { return " + predicate + "; }))";
+        return "std::count_if(" + collection + ".begin(), " + collection + ".end(), "
+                + "[](const " + elementType + "& item) { return " + predicate + "; })";
     }
 
     private String resolveFilterElementType(FilterProjectionExpression filterExpr) {

tools/code-generation/smithy/cpp-codegen/smithy-cpp-codegen/src/test/java/com/amazonaws/util/awsclientsmithygenerator/generators/waiters/WaiterJmesPathCppCodeGeneratorTest.java

@@ -555,6 +555,7 @@ void filterProjection_notWithLengthAndFieldComparison() {
             String expr = "length(services[?!(length(deployments) == `1` && runningCount == desiredCount)]) == `0`";
             String code = gen(expr, PathComparator.BOOLEAN_EQUALS);
             assertContains(code, "std::count_if");
+            assertFalse(code.contains("static_cast"), "Should not cast when comparing against literal:\n" + code);
             assertContains(code, "item.GetDeployments().size() == 1");
             assertContains(code, "item.GetRunningCount() == item.GetDesiredCount()");
             assertContains(code, "!");