WIP: Let ASTWalker visit auxiliary decls

Author: rxwei

lib/AST/ASTWalker.cpp

@@ -58,6 +58,7 @@
 #include "swift/AST/GenericParamList.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/PrettyStackTrace.h"
+#include "swift/AST/SourceFile.h"
 using namespace swift;
 
 void ASTWalker::anchor() {}
@@ -115,7 +116,22 @@ class Traversal : public ASTVisitor<Traversal, Expr*, Stmt*,
   LLVM_NODISCARD
   bool visit(Decl *D) {
     SetParentRAII SetParent(Walker, D);
-    return inherited::visit(D);
+    // Visit auxiliary decls, which may be decls from macro expansions.
+    auto moduleDecl = D->getDeclContext()->getParentModule();
+    bool alreadyFailed = false;
+    D->visitAuxiliaryDecls([&](ASTNode node) {
+      if (alreadyFailed) return;
+      auto *decl = node.dyn_cast<Decl *>();
+      if (!decl) return;
+      // Skip macro expansions if asked.
+      if (!Walker.shouldWalkMacroExpansions())
+        if (auto *sf = moduleDecl->getSourceFileContainingLocation(
+                decl->getLoc()))
+          if (sf && sf->Kind == SourceFileKind::MacroExpansion)
+            return;
+      alreadyFailed = inherited::visit(decl);
+    });
+    return alreadyFailed || inherited::visit(D);
   }
 
   LLVM_NODISCARD
@@ -439,10 +455,11 @@ class Traversal : public ASTVisitor<Traversal, Expr*, Stmt*,
         if (auto *expr = expandedNode.dyn_cast<Expr *>()) {
           if (!doIt(expr))
             return true;
-        } else if (auto *decl = expandedNode.dyn_cast<Decl *>()) {
-          if (doIt(decl))
+        } else if (auto *stmt = expandedNode.dyn_cast<Stmt *>()) {
+          if (!doIt(stmt))
             return true;
         }
+        // Decl already visited by `visitAuxiliaryDecls`.
       }
     }
     return false;