A7-1-3: Fix #601.

We did not correctly constrain the type mention for the type to
be before the variable declaration itself.

Author: lcartey

change_notes/2024-10-15-a7-1-3-multi-refs.md

@@ -0,0 +1,2 @@
+- `A7-1-3` - `CvQualifiersNotPlacedOnTheRightHandSide.ql`:
+  - Removed false positives where a correctly CV-qualified typedef variable type was also referenced in the initializer.

cpp/autosar/src/rules/A7-1-3/CvQualifiersNotPlacedOnTheRightHandSide.ql

@@ -20,14 +20,12 @@ import cpp
 import codingstandards.cpp.autosar
 
 /**
- * Holds if declaration `e` using a `TypedefType` is CV-qualified
- *
- * For example, given `using intconstptr = int * const`:
- * the predicate holds for `const/volatile intconstptr ptr1`, but not for `intconstptr ptr2`
+ * Unwrap layers of indirection that occur on the right side of the type.
  */
-predicate containsExtraSpecifiers(VariableDeclarationEntry e) {
-  e.getType().toString().matches("const %") or
-  e.getType().toString().matches("volatile %")
+Type unwrapIndirection(Type type) {
+  if type instanceof DerivedType and not type instanceof SpecifiedType
+  then result = unwrapIndirection(type.(DerivedType).getBaseType())
+  else result = type
 }
 
 // DeclStmts that have a TypedefType name use (ie TypeMention) in them
@@ -36,19 +34,19 @@ predicate containsExtraSpecifiers(VariableDeclarationEntry e) {
 from VariableDeclarationEntry e, TypedefType t, TypeMention tm
 where
   not isExcluded(e, ConstPackage::cvQualifiersNotPlacedOnTheRightHandSideQuery()) and
-  containsExtraSpecifiers(e) and
+  // Variable type is specified, and has the typedef type as a base type
+  unwrapIndirection(e.getType()).(SpecifiedType).getBaseType() = t and
   exists(string filepath, int startline |
     e.getLocation().hasLocationInfo(filepath, startline, _, _, _) and
     tm.getLocation().hasLocationInfo(filepath, startline, _, _, _) and
     e = t.getATypeNameUse() and
     tm.getMentionedType() = t and
+    // TypeMention occurs before the variable declaration
+    tm.getLocation().getStartColumn() < e.getLocation().getStartColumn() and
     exists(DeclStmt s |
       s.getDeclarationEntry(_) = e and
-      //const could fit in there
+      // TypeMention occurs after the start of the StmtDecl, with enough space for const/volatile
       tm.getLocation().getStartColumn() - s.getLocation().getStartColumn() > 5
-      //volatile could fit in there
-      //but the above condition subsumes this one
-      //l.getStartColumn() - tm.getLocation().getStartColumn() > 8
     )
   )
 select e,

cpp/autosar/test/rules/A7-1-3/CvQualifiersNotPlacedOnTheRightHandSide.expected

@@ -1,3 +1,4 @@
 | test.cpp:9:16:9:19 | definition of ptr1 | There is possibly a const or volatile specifier on the left hand side of typedef name $@. | test.cpp:1:7:1:12 | intptr | intptr |
 | test.cpp:10:19:10:22 | definition of ptr2 | There is possibly a const or volatile specifier on the left hand side of typedef name $@. | test.cpp:1:7:1:12 | intptr | intptr |
 | test.cpp:19:21:19:24 | definition of ptr8 | There is possibly a const or volatile specifier on the left hand side of typedef name $@. | test.cpp:3:7:3:17 | constintptr | constintptr |
+| test.cpp:32:23:32:26 | definition of u32d | There is possibly a const or volatile specifier on the left hand side of typedef name $@. | file:///Users/luke/git/codeql-coding-standards/cpp/common/test/includes/standard-library/cstdint.h:9:22:9:29 | uint32_t | uint32_t |

cpp/autosar/test/rules/A7-1-3/test.cpp

@@ -18,4 +18,16 @@ void f() {
   constintptr const ptr7 = &l; // COMPLIANT
   const constintptr ptr8 = &l; // NON_COMPLIANT
   inttypedef ptr9 = l;         // COMPLIANT
+}
+
+#include <cstdint>
+
+void false_positive() {
+  std::uint8_t u8{0};
+
+  auto const u32 = static_cast<std::uint32_t>(u8); // COMPLIANT - auto ignored
+  std::uint32_t const u32b = static_cast<std::uint32_t>(u8); // COMPLIANT
+
+  const auto u32c = static_cast<std::uint32_t>(u8); // COMPLIANT - auto ignored
+  const std::uint32_t u32d = static_cast<std::uint32_t>(u8); // NON_COMPLIANT
 }