Merge pull request #686 from github/lcartey/rule-5-8-no-linkage

RULE-5-8: Only consider declarations conflicting if they occur in the same link target

Author: lcartey

c/misra/src/rules/RULE-5-8/IdentifiersWithExternalLinkageNotUnique.ql

@@ -41,7 +41,25 @@ class NotUniqueExternalIdentifier extends ExternalIdentifiers {
 
   Declaration getAConflictingDeclaration() {
     not result = this and
-    isConflictingDeclaration(result, getName())
+    isConflictingDeclaration(result, getName()) and
+    // We only consider a declaration to be conflicting if it shares a link target with the external
+    // identifier. This avoids reporting false positives where multiple binaries or libraries are
+    // built in the same CodeQL database, but are not intended to be linked together.
+    exists(LinkTarget lt |
+      // External declaration can only be a function or global variable
+      lt = this.(Function).getALinkTarget() or
+      lt = this.(GlobalVariable).getALinkTarget()
+    |
+      lt = result.(Function).getALinkTarget()
+      or
+      lt = result.(GlobalVariable).getALinkTarget()
+      or
+      exists(Class c | c.getAMember() = result and c.getALinkTarget() = lt)
+      or
+      result.(LocalVariable).getFunction().getALinkTarget() = lt
+      or
+      result.(Class).getALinkTarget() = lt
+    )
   }
 }
 

change_notes/2024-09-16-rule-5-8-consider-linkage.md

@@ -0,0 +1,2 @@
+ - `RULE-5-8` - `IdentifiersWithExternalLinkageNotUnique.ql`
+   - Remove false positives where conflicting declarations do not appear in the same link target.