Rule 5.13.4: Remove false positives in macro expansions

change_notes/2026-10-19-fix-fp-rule-5-13-4-macro-expanded-literals.md

@@ -0,0 +1,2 @@
+- `RULE-5-13-4`, `M2-13-3` - `UnsignedIntegerLiteralsNotAppropriatelySuffixed.ql`, `MissingUSuffix.ql`:
+  - Remove false positives for literals in macro expansions (e.g. `0U`), as the suffix information is lost in this case. This is consistent with `RULE-7-2`.

cpp/common/src/codingstandards/cpp/rules/unsignedintegerliteralsnotappropriatelysuffixed/UnsignedIntegerLiteralsNotAppropriatelySuffixed.qll

@@ -26,6 +26,9 @@ query predicate problems(Cpp14Literal::NumericLiteral nl, string message) {
     nl.getType().getUnspecifiedType().(IntegralType).isUnsigned() and
     // The literal already has a `u` or `U` suffix.
     not nl.getValueText().regexpMatch(".*[lL]*[uU][lL]*") and
+    // Exclude literals generated by macro expansions, because the suffix information is lost in
+    // this case, so can cause false positives.
+    not nl.isInMacroExpansion() and
     // exclude literals derived from template instantiations
     not nl.isFromTemplateInstantiation(_) and
     message = literalKind + " literal is an unsigned integer but does not include a 'U' suffix."

cpp/common/test/rules/unsignedintegerliteralsnotappropriatelysuffixed/test.cpp

@@ -560,3 +560,11 @@ template <typename T> unsigned long long instantiated_literal_exclusion() {
 void test_instantiated_literal_exclusion() {
   instantiated_literal_exclusion<int>();
 }
+
+#define TEST_MACRO(value) (value)
+
+void test_literals_in_macro_argument() {
+  TEST_MACRO(1U == 0U);     // COMPLIANT
+  TEST_MACRO(020000000000); // NON_COMPLIANT[FALSE_NEGATIVE] - cannot determine
+                            // suffix in macro expansions
+}