src/jdk.jextract/share/classes/com/sun/tools/jextract/TypedefHandler.java

*** 36,68 ****
  import com.sun.tools.jextract.tree.HeaderTree;
  import com.sun.tools.jextract.tree.SimpleTreeVisitor;
  import com.sun.tools.jextract.tree.StructTree;
  import com.sun.tools.jextract.tree.Tree;
  import com.sun.tools.jextract.tree.TreeMaker;
  import com.sun.tools.jextract.tree.TreePrinter;
  import com.sun.tools.jextract.tree.TypedefTree;
  import jdk.internal.clang.Cursor;
  
  /**
   * This visitor handles certain typedef declarations.
   *
   * 1. Remove redundant typedefs.
   * 2. Rename typedef'ed anonymous type definitions like
   *        typedef struct { int x; int y; } Point;
   */
! final class TypedefHandler extends SimpleTreeVisitor<Void, Void> {
      private final TreeMaker treeMaker = new TreeMaker();
  
      // Potential Tree instances that will go into transformed HeaderTree
      // are collected in this list.
      private final List<Tree> decls = new ArrayList<>();
  
      // Tree instances that are to be replaced from "decls" list are
      // saved in the following Map.
      private final Map<Cursor, Tree> replacements = new HashMap<>();
  
!     HeaderTree transform(HeaderTree ht) {
          // Process all header declarations are collect potential
          // declarations that will go into transformed HeaderTree
          // into the this.decls field.
          ht.accept(this, null);
  
--- 36,72 ----
  import com.sun.tools.jextract.tree.HeaderTree;
  import com.sun.tools.jextract.tree.SimpleTreeVisitor;
  import com.sun.tools.jextract.tree.StructTree;
  import com.sun.tools.jextract.tree.Tree;
  import com.sun.tools.jextract.tree.TreeMaker;
+ import com.sun.tools.jextract.tree.TreePhase;
  import com.sun.tools.jextract.tree.TreePrinter;
  import com.sun.tools.jextract.tree.TypedefTree;
  import jdk.internal.clang.Cursor;
  
  /**
   * This visitor handles certain typedef declarations.
   *
   * 1. Remove redundant typedefs.
   * 2. Rename typedef'ed anonymous type definitions like
   *        typedef struct { int x; int y; } Point;
+  * 3. Remove redundant struct/union/enum forward/backward declarations
   */
! final class TypedefHandler extends SimpleTreeVisitor<Void, Void>
!         implements TreePhase {
      private final TreeMaker treeMaker = new TreeMaker();
  
      // Potential Tree instances that will go into transformed HeaderTree
      // are collected in this list.
      private final List<Tree> decls = new ArrayList<>();
  
      // Tree instances that are to be replaced from "decls" list are
      // saved in the following Map.
      private final Map<Cursor, Tree> replacements = new HashMap<>();
  
!     @Override
!     public HeaderTree transform(HeaderTree ht) {
          // Process all header declarations are collect potential
          // declarations that will go into transformed HeaderTree
          // into the this.decls field.
          ht.accept(this, null);
  
*** 85,100 ****
--- 89,154 ----
          decls.add(tree);
          return null;
      }
  
      @Override
+     public Void visitEnum(EnumTree e, Void v) {
+         /*
+          * If we're seeing a forward/backward declaration of an
+          * enum which is definied elsewhere in this compilation
+          * unit, ignore it. If no definition is found, we want to
+          * leave the declaration so that dummy definition will be
+          * generated.
+          *
+          * Example:
+          *
+          *  enum Color ; // <-- forward declaration
+          *  struct Point { int i; int j; };
+          *  struct Point3D { int i; int j; int k; };
+          *  struct Point3D; // <-- backward declaration
+          */
+ 
+         // include this only if this is a definition or a declaration
+         // for which no definition is found elsewhere.
+         if (e.isDefinition() || !e.definition().isPresent()) {
+             decls.add(e);
+         }
+         return null;
+     }
+ 
+     @Override
      public Void visitHeader(HeaderTree ht, Void v) {
          ht.declarations().forEach(decl -> decl.accept(this, null));
          return null;
      }
  
      @Override
+     public Void visitStruct(StructTree s, Void v) {
+         /*
+          * If we're seeing a forward/backward declaration of
+          * a struct which is definied elsewhere in this compilation
+          * unit, ignore it. If no definition is found, we want to
+          * leave the declaration so that dummy definition will be
+          * generated.
+          *
+          * Example:
+          *
+          *  struct Point; // <-- forward declaration
+          *  struct Point { int i; int j; };
+          *  struct Point3D { int i; int j; int k; };
+          *  struct Point3D; // <-- backward declaration
+          */
+ 
+         // include this only if this is a definition or a declaration
+         // for which no definition is found elsewhere.
+         if (s.isDefinition() || !s.definition().isPresent()) {
+             decls.add(s);
+         }
+         return null;
+     }
+ 
+     @Override
      public Void visitTypedef(TypedefTree tt, Void v) {
          Optional<Tree> def = tt.typeDefinition();
          if (def.isPresent()) {
              Tree defTree = def.get();
              if (defTree instanceof StructTree) {