Merge pull request #63 from lcartey/lcartey/dead-code-static-asserts

`M0-1-9`: Exclude more compiler generated statements

Author: lcartey

change_notes/2022-08-18-dead-code-static-asserts.md

@@ -0,0 +1,2 @@
+ - `M0-1-9` - `DeadCode.ql`:
+   - More compiler generated statements are now excluded from being reported as dead code, including compiler generated statements for `static_assert` calls.

cpp/autosar/src/rules/M0-1-9/DeadCode.ql

@@ -51,7 +51,9 @@ predicate isDeadStmt(Stmt s) {
   // - The initializers for each of the variables are pure
   exists(DeclStmt ds |
     ds = s and
-    forall(Declaration d | d = ds.getADeclaration() |
+    // Use forex so that we don't flag "fake" generated `DeclStmt`s (e.g. those generated by the
+    // extractor for static_asserts) with no actual declarations
+    forex(Declaration d | d = ds.getADeclaration() |
       exists(LocalScopeVariable v |
         d = v and
         v.getInitializer().getExpr().isPure() and
@@ -123,5 +125,7 @@ where
   // output". We therefore exclude unreachable statements as they are, by definition, not executed.
   not s.getBasicBlock() = any(UnreachableBasicBlock ubb).getABasicBlock() and
   // Exclude code generated by macros, because the code may be "live" in other instantiations
-  not s.isAffectedByMacro()
+  not s.isAffectedByMacro() and
+  // Exclude compiler generated statements
+  not s.isCompilerGenerated()
 select s, "This statement is dead code."

cpp/autosar/test/rules/M0-1-9/test.cpp

@@ -76,5 +76,7 @@ int test_dead_code(int x) {
   } catch (...) {   // NON_COMPLIANT
   }
 
+  static_assert(1); // COMPLIANT
+
   return live5 + live6; // COMPLIANT
 }