Merge pull request #550 from kraiouchkine/a16-2-2-fix-453

A16-2-2: Exclude reporting of nested redundant includes

Author: knewbury01

change_notes/2024-03-04-fix-fp-a16-2-2.md

@@ -0,0 +1,2 @@
+- `A16-2-2` - `UnusedIncludeDirectives.ql`:
+  - Address FP reported in #453. Exclude reporting of redundant include directives indirectly included by included files.

cpp/autosar/src/rules/A16-2-2/UnusedIncludeDirectives.ql

@@ -223,10 +223,19 @@ private predicate firstReliableProvide(File f, File g, int line) {
 
 cached
 predicate mayProvideFirst(IncludeDepends i, File g) {
-  // i may provide g and does not come after a reliable include of g.
+  // i may provide g
   i.provides(g) and
-  not exists(int line | firstReliableProvide(i.getFile(), g, line) |
-    line < i.getLocation().getStartLine()
+  (
+    // and does not come after a reliable include of g.
+    not exists(int line | firstReliableProvide(i.getFile(), g, line) |
+      line < i.getLocation().getStartLine()
+    )
+    or
+    // or it comes after a reliable include of g, and although redundant,
+    // is not necessarily an issue e.g. in the case of libraries with
+    // public header forwards to an internal header.
+    // therefore, hold for transitive includes as well to exclude those results.
+    not i.getIncludedFile() = g
   )
 }
 

cpp/autosar/test/rules/A16-2-2/internal.h

@@ -0,0 +1 @@
+void f();

cpp/autosar/test/rules/A16-2-2/test.hpp

@@ -1 +1,3 @@
-void f();
+#include "z.h"
+
+void g() { f(); }

cpp/autosar/test/rules/A16-2-2/test2.cpp

@@ -0,0 +1,7 @@
+#include "test.hpp" // COMPLIANT
+#include "z.h"      // COMPLIANT
+
+void test() {
+  f();
+  g();
+}

cpp/autosar/test/rules/A16-2-2/z.h

@@ -0,0 +1 @@
+#include "internal.h"