Merge pull request #303 from github/lcartey/func-c-style

__func__ excluded from C-style queries

Author: mbaluda

change_notes/2023-05-02-func-c-style.md

@@ -0,0 +1,3 @@
+ * Exclude the use of `__func__` from certain queries, as it is the proscribed way to return the name of the current function:
+   * `A27-0-4` - Use of the value returned by `__func__` is no longer flagged as a use of C-style strings.
+   * `A18-1-1` - `__func__` is no longer flagged as a declaration of a variable using C-style arrays.

cpp/autosar/src/rules/A18-1-1/CStyleArraysUsed.ql

@@ -30,5 +30,7 @@ class StaticConstExprArrayDataMember extends MemberVariable {
 from Variable v
 where
   not isExcluded(v, BannedSyntaxPackage::cStyleArraysUsedQuery()) and
-  exists(ArrayType a | v.getType() = a | not v instanceof StaticConstExprArrayDataMember)
+  exists(ArrayType a | v.getType() = a | not v instanceof StaticConstExprArrayDataMember) and
+  // Exclude the compiler generated __func__ as it is the only way to access the function name information
+  not v.getName() = "__func__"
 select v, "Variable " + v.getName() + " declares a c-style array."

cpp/autosar/src/rules/A27-0-4/CStyleStringsUsed.ql

@@ -36,5 +36,6 @@ where
     e = any(FunctionCall fc).getArgument(_) and
     e.getUnspecifiedType().(PointerType).getBaseType*() instanceof CharType
   ) and
-  DataFlow::localFlow(DataFlow::exprNode(cs), DataFlow::exprNode(e))
+  DataFlow::localFlow(DataFlow::exprNode(cs), DataFlow::exprNode(e)) and
+  not cs = any(LocalVariable lv | lv.getName() = "__func__").getInitializer().getExpr()
 select cs, "Usage of C-style string in $@.", e, "expression"

cpp/autosar/test/rules/A18-1-1/test.cpp

@@ -10,5 +10,7 @@ int test_c_arrays() {
 
   int x[100];                 // NON_COMPLIANT
   constexpr int a[]{0, 1, 2}; // NON_COMPLIANT
+
+  __func__; // COMPLAINT
   return 0;
 }

cpp/autosar/test/rules/A27-0-4/test.cpp

@@ -26,4 +26,5 @@ void f2() {
   f1(a1);
   f1(a2);
   f1(s.c_str()); // NON_COMPLIANT
+  __func__;
 }