From 8f61a6bc9859f5a3b528a8e0797532fc0bbb9d6e Mon Sep 17 00:00:00 2001
From: Luke Cartey <lcartey@github.com>
Date: Tue, 2 May 2023 12:01:51 +0100
Subject: [PATCH] __func__ excluded from C-style queries

Exclude `__func__` from queries that prohibit c-style strings and
arrays, as it is the proscribed way to return the function name.
---
 change_notes/2023-05-02-func-c-style.md            | 3 +++
 cpp/autosar/src/rules/A18-1-1/CStyleArraysUsed.ql  | 4 +++-
 cpp/autosar/src/rules/A27-0-4/CStyleStringsUsed.ql | 3 ++-
 cpp/autosar/test/rules/A18-1-1/test.cpp            | 2 ++
 cpp/autosar/test/rules/A27-0-4/test.cpp            | 1 +
 5 files changed, 11 insertions(+), 2 deletions(-)
 create mode 100644 change_notes/2023-05-02-func-c-style.md

diff --git a/change_notes/2023-05-02-func-c-style.md b/change_notes/2023-05-02-func-c-style.md
new file mode 100644
index 0000000000..46e1710010
--- /dev/null
+++ b/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.
\ No newline at end of file
diff --git a/cpp/autosar/src/rules/A18-1-1/CStyleArraysUsed.ql b/cpp/autosar/src/rules/A18-1-1/CStyleArraysUsed.ql
index 83d0220c5a..0494e86607 100644
--- a/cpp/autosar/src/rules/A18-1-1/CStyleArraysUsed.ql
+++ b/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."
diff --git a/cpp/autosar/src/rules/A27-0-4/CStyleStringsUsed.ql b/cpp/autosar/src/rules/A27-0-4/CStyleStringsUsed.ql
index be8bda1f0b..b24a4a96cf 100644
--- a/cpp/autosar/src/rules/A27-0-4/CStyleStringsUsed.ql
+++ b/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"
diff --git a/cpp/autosar/test/rules/A18-1-1/test.cpp b/cpp/autosar/test/rules/A18-1-1/test.cpp
index 21eb783717..90596780d9 100644
--- a/cpp/autosar/test/rules/A18-1-1/test.cpp
+++ b/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;
 }
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A27-0-4/test.cpp b/cpp/autosar/test/rules/A27-0-4/test.cpp
index 10ee885979..e73c37ea64 100644
--- a/cpp/autosar/test/rules/A27-0-4/test.cpp
+++ b/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__;
 }
\ No newline at end of file