A16-0-1: exclusions for handling else and elif

Author: knewbury01

change_notes/2024-01-31-exclusion-a16-0-1.md

@@ -0,0 +1,2 @@
+`A16-0-1`: `cpp/autosar/pre-processor-shall-only-be-used-for-certain-directives-patterns`
+    - Exclude all preprocessor elses and also consider elifs separately (ie do not affect valid ifs) but not valid if not meeting the same criteria as an ifdef etc.

cpp/autosar/src/rules/A16-0-1/PreProcessorShallOnlyBeUsedForCertainDirectivesPatterns.ql

@@ -21,13 +21,26 @@ import cpp
 import codingstandards.cpp.autosar
 import codingstandards.cpp.FunctionLikeMacro
 
+class PermittedInnerDirectiveType extends PreprocessorDirective {
+  PermittedInnerDirectiveType() {
+    //permissive listing for directives that can be used in a valid wrapper
+    this instanceof MacroWrapper or
+    this instanceof PreprocessorEndif or
+    this instanceof Include or
+    this instanceof PermittedMacro or
+    this instanceof PreprocessorElif or
+    this instanceof PreprocessorElse
+  }
+}
+
 class PermittedDirectiveType extends PreprocessorDirective {
   PermittedDirectiveType() {
     //permissive listing in case directive types modelled in ql ever expands (example non valid directives)
     this instanceof MacroWrapper or
     this instanceof PreprocessorEndif or
     this instanceof Include or
-    this instanceof PermittedMacro
+    this instanceof PermittedMacro or
+    this instanceof PreprocessorElse
   }
 }
 
@@ -73,7 +86,7 @@ class MacroWrapper extends PreprocessorIfndef {
 class AcceptableWrapper extends PreprocessorBranch {
   AcceptableWrapper() {
     forall(Element inner | not inner instanceof Comment and this = getAGuard(inner) |
-      inner instanceof PermittedDirectiveType
+      inner instanceof PermittedInnerDirectiveType
     )
   }
 }

cpp/autosar/test/rules/A16-0-1/PreProcessorShallOnlyBeUsedForCertainDirectivesPatterns.expected

@@ -2,3 +2,6 @@
 | test.cpp:9:1:9:26 | #define OBJECTLIKE_MACRO 1 | Preprocessor directive used for conditional compilation. |
 | test.cpp:10:1:10:35 | #define FUNCTIONLIKE_MACRO(X) X + 1 | Preprocessor directive used for conditional compilation. |
 | test.cpp:11:1:11:37 | #define FUNCTIONLIKE_MACROTWO() 1 + 1 | Preprocessor directive used for conditional compilation. |
+| test.cpp:33:1:33:26 | #ifdef OBJECTLIKE_MACRO_NO | Preprocessor directive used for conditional compilation. |
+| test.cpp:35:1:35:26 | #elif OBJECTLIKE_MACRO > 0 | Preprocessor directive used for conditional compilation. |
+| test.cpp:39:1:39:23 | #ifdef OBJECTLIKE_MACRO | Preprocessor directive used for conditional compilation. |

cpp/autosar/test/rules/A16-0-1/test.cpp

@@ -17,3 +17,28 @@ int g;
 #ifndef TESTHEADER // COMPLIANT
 #include <string>  //COMPLIANT
 #endif             // COMPLIANT
+
+#ifdef MACRO_ENABLED // COMPLIANT
+#include <string>    // COMPLIANT
+#else                // COMPLIANT
+#include <string>    // COMPLIANT
+#endif               // COMPLIANT
+
+#ifdef MACRO_ENABLED_NON  // COMPLIANT
+#include <string>         // COMPLIANT
+#elif MACRO_ENABLED_OTHER // COMPLIANT
+#include <string>         // COMPLIANT
+#endif                    // COMPLIANT
+
+#ifdef OBJECTLIKE_MACRO_NO // NON_COMPLIANT
+int x = 0;                 // not present
+#elif OBJECTLIKE_MACRO > 0 // NON_COMPLIANT
+int x = 1;  // present
+#endif                     // COMPLIANT
+
+#ifdef OBJECTLIKE_MACRO // NON_COMPLIANT
+int x1 = 0;             // present
+#elif OBJECTLIKE_MACRO >                                                       \
+    -1 // COMPLIANT - by technicality of conditional compilation
+int x1 = 1; // not present
+#endif // COMPLIANT