Fix #9488: MISRA addon: False positive for rule 10.6 in test for rule 10.1 (#5598)

addons/misra.py

@@ -2387,6 +2387,9 @@ class MisraChecker:
                     e = getEssentialType(token.astOperand2)
                 if not e:
                     continue
+                if e == "char" and vt1.type == "int":
+                    # When arithmetic operations are performed on char values, they are usually promoted to int
+                    continue
                 lhsbits = vt1.bits if vt1.bits else bitsOfEssentialType(vt1.type)
                 if lhsbits > bitsOfEssentialType(e):
                     self.reportError(token, 10, 6)

addons/test/misra/misra-test.c

@@ -749,7 +749,7 @@ static void misra_10_6(u8 x, char c1, char c2) {
   u16 y1 = x+x; // 10.6
   u16 y2 = (0x100u - 0x80u); // rhs is not a composite expression because it's a constant expression
   u16 z = ~u8 x ;//10.6
-  s32 i = c1 - c2; // 10.3 FIXME: False positive for 10.6 (this is compliant). Trac #9488
+  s32 i = c1 - c2; // 10.3
   struct misra_10_6_s s;
   s.a = x & 1U; // no-warning (#10487)
 }