Merge pull request #882 from github/michaelrfairhurst/mark-amendment-4-rule-1-4-implemented

Implement Rule-1-4's rule amendment from Amendment4 (also amended in Amd3)

Author: MichaelRFairhurst

amendments.csv

@@ -24,7 +24,7 @@ c,MISRA-C-2012,Amendment4,RULE-8-9,Yes,Clarification,Yes,Import
 c,MISRA-C-2012,Amendment4,RULE-9-4,Yes,Clarification,Yes,Import
 c,MISRA-C-2012,Amendment4,RULE-10-1,Yes,Clarification,Yes,Import
 c,MISRA-C-2012,Amendment4,RULE-18-3,Yes,Clarification,Yes,Import
-c,MISRA-C-2012,Amendment4,RULE-1-4,Yes,Replace,No,Easy
+c,MISRA-C-2012,Amendment4,RULE-1-4,Yes,Replace,Yes,Easy
 c,MISRA-C-2012,Amendment4,RULE-9-1,Yes,Refine,Yes,Easy
 c,MISRA-C-2012,Corrigendum2,DIR-4-10,Yes,Clarification,Yes,Import
 c,MISRA-C-2012,Corrigendum2,RULE-7-4,Yes,Refine,Yes,Easy

c/misra/test/rules/RULE-1-4/EmergentLanguageFeaturesUsed.expected

@@ -1,7 +1 @@
-| test.c:2:1:2:22 | #include <stdatomic.h> | Usage of emergent language feature. |
-| test.c:4:1:4:20 | #include <threads.h> | Usage of emergent language feature. |
 | test.c:7:1:7:32 | #define __STDC_WANT_LIB_EXT1__ 1 | Usage of emergent language feature. |
-| test.c:12:26:12:40 | atomic_new_type | Usage of emergent language feature. |
-| test.c:17:15:17:15 | i | Usage of emergent language feature. |
-| test.c:24:27:24:28 | i3 | Usage of emergent language feature. |
-| test.c:25:28:25:29 | i4 | Usage of emergent language feature. |

c/misra/test/rules/RULE-1-4/test.c

@@ -1,15 +1,15 @@
 #include <stdalign.h>    //COMPLIANT
-#include <stdatomic.h>   //NON_COMPLIANT
+#include <stdatomic.h>   //COMPLIANT
 #include <stdnoreturn.h> //COMPLIANT
-#include <threads.h>     //NON_COMPLIANT
+#include <threads.h>     //COMPLIANT
 
-#define MACRO(x) _Generic((x), int : 0, long : 1) // NON_COMPLIANT
+#define MACRO(x) _Generic((x), int : 0, long : 1) // COMPLIANT
 #define __STDC_WANT_LIB_EXT1__ 1                  // NON_COMPLIANT
 
 _Noreturn void f0(); // COMPLIANT
 
 typedef int new_type;                     // COMPLIANT
-typedef _Atomic new_type atomic_new_type; // NON_COMPLIANT
+typedef _Atomic new_type atomic_new_type; // COMPLIANT
 
 void f(int p) {
   int i0 = _Generic(p, int : 0, long : 1); // COMPLIANT
@@ -21,6 +21,6 @@ void f(int p) {
   int a = _Alignof(int); // COMPLIANT
   int a1 = alignof(int); // COMPLIANT
 
-  static thread_local int i3;  // NON_COMPLIANT
-  static _Thread_local int i4; // NON_COMPLIANT
+  static thread_local int i3;  // COMPLIANT
+  static _Thread_local int i4; // COMPLIANT
 }

change_notes/2025-03-31-allow-atomics-threads-and-threadlocals-in-misra-c.md

@@ -0,0 +1,2 @@
+ - `RULE-1-4` - `EmergentLanguageFeaturesUsed.ql`:
+   - Allow usage of atomics, `thread.h`, and `_Thread_local` as per Misra C 2012 Amendment 4.

cpp/common/src/codingstandards/cpp/Emergent.qll

@@ -6,24 +6,6 @@ import cpp
 module C11 {
   abstract class EmergentLanguageFeature extends Element { }
 
-  class AtomicVariableSpecifier extends EmergentLanguageFeature, Variable {
-    AtomicVariableSpecifier() {
-      getType().(DerivedType).getBaseType*().getASpecifier().getName() = "atomic"
-    }
-  }
-
-  class AtomicDeclaration extends EmergentLanguageFeature, Declaration {
-    AtomicDeclaration() { getASpecifier().getName() = "atomic" }
-  }
-
-  class ThreadLocalDeclaration extends EmergentLanguageFeature, Declaration {
-    ThreadLocalDeclaration() { getASpecifier().getName() = "is_thread_local" }
-  }
-
-  class EmergentHeader extends EmergentLanguageFeature, Include {
-    EmergentHeader() { getIncludedFile().getBaseName() = ["stdatomic.h", "threads.h"] }
-  }
-
   class LibExt1Macro extends EmergentLanguageFeature, Macro {
     LibExt1Macro() {
       getName() = "__STDC_WANT_LIB_EXT1__" and