Merge pull request #744 from github/lcartey/rule-11-3-specified-void-type

`RULE-11-*`: Improve detection of const void pointers

Author: nicolaswill

c/misra/src/rules/RULE-11-5/ConversionFromPointerToVoidIntoPointerToObject.ql

@@ -19,7 +19,7 @@ import codingstandards.cpp.Pointers
 from Cast cast, VoidPointerType type, PointerToObjectType newType
 where
   not isExcluded(cast, Pointers1Package::conversionFromPointerToVoidIntoPointerToObjectQuery()) and
-  type = cast.getExpr().getUnderlyingType() and
+  type = cast.getExpr().getUnspecifiedType() and
   newType = cast.getUnderlyingType() and
   not isNullPointerConstant(cast.getExpr())
 select cast,

c/misra/test/rules/RULE-11-3/CastBetweenObjectPointerAndDifferentObjectType.expected

@@ -2,3 +2,7 @@
 | test.c:14:8:14:9 | (int *)... | Cast performed between a pointer to object type (char) and a pointer to a different object type (int). |
 | test.c:15:8:15:25 | (int *)... | Cast performed between a pointer to object type (short) and a pointer to a different object type (int). |
 | test.c:15:15:15:25 | (short *)... | Cast performed between a pointer to object type (char) and a pointer to a different object type (short). |
+| test.c:20:3:20:17 | (const int *)... | Cast performed between a pointer to object type (char) and a pointer to a different object type (const int). |
+| test.c:21:3:21:16 | (int *)... | Cast performed between a pointer to object type (char) and a pointer to a different object type (int). |
+| test.c:22:20:22:21 | (int *)... | Cast performed between a pointer to object type (char) and a pointer to a different object type (int). |
+| test.c:23:3:23:18 | (long long *)... | Cast performed between a pointer to object type (int) and a pointer to a different object type (long long). |

c/misra/test/rules/RULE-11-3/test.c

@@ -13,4 +13,12 @@ void f1(void) {
   int *v8 = (int *)0;         // COMPLIANT
   v8 = v2;                    // NON_COMPLIANT
   v8 = (int *)(short *)v2;    // NON_COMPLIANT
+  (const void *)v1;           // COMPLIANT
+  const void *v9 = v1;        // COMPLIANT
+  (int *)v9;                  // COMPLIANT - cast from void*
+  (const void *)v2;           // COMPLIANT
+  (const int *)v2;            // NON_COMPLIANT
+  (int *const)v2;             // NON_COMPLIANT
+  int *const v10 = v2;        // NON_COMPLIANT
+  (long long *)v10;           // NON_COMPLIANT
 }

c/misra/test/rules/RULE-11-4/ConversionBetweenPointerToObjectAndIntegerType.expected

@@ -1,6 +1,6 @@
 | test.c:6:21:6:37 | (unsigned int)... | Cast from pointer to object type 'unsigned int *' to integer type 'unsigned int'. | test.c:6:21:6:37 | (unsigned int)... |  |
 | test.c:8:8:8:24 | (unsigned int)... | Cast from pointer to object type 'unsigned int *' to integer type 'unsigned int'. | test.c:8:8:8:24 | (unsigned int)... |  |
 | test.c:12:22:12:39 | (unsigned int *)... | Cast from integer type 'unsigned int' to pointer to object type 'unsigned int *'. | test.c:12:22:12:39 | (unsigned int *)... |  |
-| test.c:15:1:15:24 | #define FOO (int *)0x200 | Cast from integer type 'int' to pointer to object type 'int *'. | test.c:15:1:15:24 | #define FOO (int *)0x200 |  |
-| test.c:23:3:23:22 | (int *)... | Cast from integer type 'int' to pointer to object type 'int *' from expansion of macro $@. | test.c:17:1:17:34 | #define FOO_FUNCTIONAL(x) (int *)x | FOO_FUNCTIONAL |
-| test.c:24:14:24:25 | (int *)... | Cast from integer type 'int' to pointer to object type 'int *' from expansion of macro $@. | test.c:18:1:18:23 | #define FOO_INSERT(x) x | FOO_INSERT |
+| test.c:18:1:18:24 | #define FOO (int *)0x200 | Cast from integer type 'int' to pointer to object type 'int *'. | test.c:18:1:18:24 | #define FOO (int *)0x200 |  |
+| test.c:26:3:26:22 | (int *)... | Cast from integer type 'int' to pointer to object type 'int *' from expansion of macro $@. | test.c:20:1:20:34 | #define FOO_FUNCTIONAL(x) (int *)x | FOO_FUNCTIONAL |
+| test.c:27:14:27:25 | (int *)... | Cast from integer type 'int' to pointer to object type 'int *' from expansion of macro $@. | test.c:21:1:21:23 | #define FOO_INSERT(x) x | FOO_INSERT |

c/misra/test/rules/RULE-11-4/test.c

@@ -10,6 +10,9 @@ void f1(void) {
   unsigned int *v4 = 0;                      // COMPLIANT
   unsigned int *v5 = NULL;                   // COMPLIANT
   unsigned int *v6 = (unsigned int *)v2;     // NON_COMPLIANT
+  const void *v7 = 0;
+  (unsigned int)v7; // COMPLIANT - cast const void to int
+  (const void *)v1; // COMPLIANT - casting int to const void
 }
 
 #define FOO (int *)0x200 // NON_COMPLIANT

c/misra/test/rules/RULE-11-5/ConversionFromPointerToVoidIntoPointerToObject.expected

@@ -1 +1,2 @@
 | test.c:6:13:6:21 | (int *)... | Cast performed from a void pointer into a pointer to an object (int *). |
+| test.c:11:3:11:11 | (int *)... | Cast performed from a void pointer into a pointer to an object (int *). |

c/misra/test/rules/RULE-11-5/test.c

@@ -7,4 +7,8 @@ void f1(void) {
   v2 = NULL;             // COMPLIANT
   void *v3 = (void *)v1; // COMPLIANT
   v3 = (void *)v2;       // COMPLIANT
+  const void *v4 = 0;
+  (int *)v4;        // NON_COMPLIANT - const in type is irrelevant
+  (const void *)v1; // COMPLIANT - casting is from void to void, const addition
+                    // should be irrelevant
 }

c/misra/test/rules/RULE-11-7/test.c

@@ -7,4 +7,12 @@ void f1(void) {
   float v4 = (float)(bool)v1; // NON_COMPLIANT
   v1 = (int *)v2;             // NON_COMPLIANT
   v4 = (float)v3;             // COMPLIANT
+  void *v5 = 0;
+  const void *v6 = 0;
+  // void pointers (regardless of specifier) are not pointers to object, so all
+  // these examples are compliant according to this rule
+  (bool)v5;         // COMPLIANT
+  (bool)v6;         // COMPLIANT
+  (void *)v2;       // COMPLIANT
+  (const void *)v2; // COMPLIANT
 }

change_notes/2024-10-11-specifiers-rule-11-misra-c.md

@@ -0,0 +1,4 @@
+- `RULE-11-3`, `RULE-11-4`, `RULE-11-5`, `RULE-11-7` - `CastBetweenObjectPointerAndDifferentObjectType.ql`, `ConversionBetweenPointerToObjectAndIntegerType.ql`, `ConversionFromPointerToVoidIntoPointerToObject.ql`, `CastBetweenPointerToObjectAndNonIntArithmeticType.ql`:
+  - Removed false positives where casts involved a specified void type pointer, e.g. `const void*`, which should not be considered as a pointer to object.
+- `RULE-11-5` - `ConversionFromPointerToVoidIntoPointerToObject.ql`:
+  - Addressed false negatives where the pointer-to-void was specified.

cpp/common/src/codingstandards/cpp/Pointers.qll

@@ -80,9 +80,9 @@ predicate isCastNullPointerConstant(Cast c) {
 class PointerToObjectType extends PointerType {
   PointerToObjectType() {
     not (
-      this.getUnderlyingType() instanceof FunctionPointerType or
-      this.getUnderlyingType() instanceof VoidPointerType or
-      this.getBaseType().getUnderlyingType() instanceof IncompleteType
+      this.getUnspecifiedType() instanceof FunctionPointerType or
+      this.getUnspecifiedType() instanceof VoidPointerType or
+      this.getBaseType().getUnspecifiedType() instanceof IncompleteType
     )
   }
 }