Fix CompleteDefinition of struct being dragged into output because of union fields

libcextract/Closure.cpp

@@ -87,7 +87,10 @@ bool DeclClosureVisitor::TraverseDecl(Decl *decl)
 {
   DO_NOT_RUN_IF_ALREADY_ANALYZED(decl);
   Mark_As_Analyzed(decl);
-  return RecursiveASTVisitor::TraverseDecl(decl);
+  Stack.push_back(decl);
+  bool ret = RecursiveASTVisitor::TraverseDecl(decl);
+  Stack.pop_back();
+  return ret;
 }
 
 bool DeclClosureVisitor::VisitFunctionDecl(FunctionDecl *decl)
@@ -506,7 +509,15 @@ bool DeclClosureVisitor::ParentRecordDeclHelper(TagDecl *decl)
   /* In case this references a struct/union defined inside a struct (nested
      struct), then we also need to analyze the parent struct.  */
   RecordDecl *parent = dyn_cast<RecordDecl>(decl->getLexicalDeclContext());
-  if (parent) {
+  Decl *analysis_parent = nullptr;
+
+  /* Check if we are not coming from an analysis from the RecordDecl, i.e. from
+     a stack perspective the Decl that is at the bottom of the Decl.  */
+  if (Stack.size() >= 2) {
+    analysis_parent = Stack[Stack.size() - 2];
+  }
+
+  if (parent && analysis_parent != parent) {
     /* If the parent struct is flagged as not needing a complete definition
        then we need to set it to true, else the nested struct won't be
        output as of only a partial definition of the parent struct is

libcextract/Closure.hh

@@ -140,7 +140,10 @@ class DeclClosureVisitor : public RecursiveASTVisitor<DeclClosureVisitor>
   public:
   DeclClosureVisitor(ASTUnit *ast)
     : RecursiveASTVisitor(),
-      AST(ast)
+      AST(ast),
+      Closure(),
+      AnalyzedDecls(),
+      Stack()
   {
   }
 
@@ -273,4 +276,14 @@ class DeclClosureVisitor : public RecursiveASTVisitor<DeclClosureVisitor>
 
   /** The set of all analyzed Decls.  */
   std::unordered_set<Decl *> AnalyzedDecls;
+
+  /** Stack of Decls.  Implement using a vector because we may need to access
+      the second element on the top, and we also need its continuity.  */
+  llvm::SmallVector<Decl *, 128> Stack;
+
+  /** Return what is on top of our stack.  */
+  inline Decl *Stack_Top(void)
+  {
+    return Stack[Stack.size() - 1];
+  }
 };

testsuite/small/record-nested-5.c

@@ -0,0 +1,20 @@
+/* { dg-options "-DCE_EXTRACT_FUNCTIONS=f -DCE_NO_EXTERNALIZATION" }*/
+
+struct ll;
+
+int get(struct ll *);
+
+struct ll {
+  union {
+    unsigned long key;
+    void *key_ptr;
+  };
+  struct ll *next;
+};
+
+int f(struct ll *l)
+{
+  return get(l);
+}
+
+/* { dg-final { scan-tree-dump-not "struct ll *{" } } */