Fix #14607: MISRA: make rule 10.3 warn on bool <- 0/1 in C99 and later (#8340)

Fix #14607.

This updates MISRA rule 10.3 in `addons/misra.py` so that assignments of
integer literals `0` and `1` to `bool` are only exempted in C89.

Behavior after this change:
- C89: keep the existing behavior and allow `bool <- 0/1`
- C99/C11/C17/C18/C23: report MISRA 10.3 for `bool <- 0/1`

The motivation is that in C99 and later, `bool`/`true`/`false` are
available, so the current unconditional exemption for `0` and `1` causes
a MISRA 10.3 false negative.

Changes:
- update `addons/misra.py` rule 10.3 to make the `bool <- 0/1` exemption
standard-dependent
- add C89-side coverage in `addons/test/misra/misra-test.c`
- add C11-side coverage in `addons/test/misra/misra-test-c11.c`
- add a release notes entry

Related Context:
- Earlier discussion: #7110
- Downstream issue: commaai/panda#2105

Author: varshneydevansh

addons/misra.py

@@ -2472,7 +2472,14 @@ def get_category(essential_type):
                 rhs_category = get_category(rhs)
                 if lhs_category and rhs_category and lhs_category != rhs_category and rhs_category not in ('signed','unsigned'):
                     self.reportError(tok, 10, 3)
-                if bitsOfEssentialType(lhs) < bitsOfEssentialType(rhs) and (lhs != "bool" or tok.astOperand2.str not in ('0','1')):
+                find_std = cfg.standards.c if cfg.standards and cfg.standards.c else self.stdversion
+                allow_bool_literal_0_1 = (
+                    find_std == "c89" and
+                    lhs == "bool" and
+                    tok.astOperand2 and
+                    tok.astOperand2.str in ('0', '1')
+                )
+                if bitsOfEssentialType(lhs) < bitsOfEssentialType(rhs) and not allow_bool_literal_0_1:
                     self.reportError(tok, 10, 3)
 
     def misra_10_4(self, data):

addons/test/misra/misra-test-c11.c

@@ -2,6 +2,7 @@
 // ~/cppcheck/cppcheck --dump misra/misra-test-c11.c --std=c11
 // ~/cppcheck/cppcheck --dump -DDUMMY --suppress=uninitvar --inline-suppr misra/misra-test-c11.c --std=c11 --platform=unix64 && python3 ../misra.py -verify misra/misra-test-c11.c.dump
 
+#include <stdbool.h>
 #include <stdint.h>
 
 typedef unsigned int UINT_TYPEDEF;
@@ -23,3 +24,13 @@ static void misra6_1_fn(void) {
     struct_with_bitfields s;
     s.h = 61;
 }
+
+static void misra_10_3_c11(void) {
+    bool b = false;
+    bool b0 = 0; // 10.3
+    bool b1 = 1; // 10.3
+    b = 0; // 10.3
+    b = 1; // 10.3
+    b = false; // no-warning
+    b = true; // no-warning
+}

addons/test/misra/misra-test.c

@@ -726,6 +726,10 @@ static void misra_10_3(uint32_t u32a, uint32_t u32b) {
     const char c = '0'; // no-warning
     bool b = true; // no-warning
     uint32_t u = UINT32_C(10); // no-warning
+    bool b0 = 0; // no-warning
+    bool b1 = 1; // no-warning
+    b = 0; // no-warning
+    b = 1; // no-warning
 }
 
 static void misra_10_4(u32 x, s32 y) {

releasenotes.txt

@@ -5,7 +5,7 @@ Major bug fixes & crashes:
 -
 
 New checks:
--
+- MISRA C 2012 rule 10.3 now warns on assigning integer literals 0 and 1 to bool in C99 and later while preserving the existing C89 behavior.
 
 C/C++ support:
 -