[AST] Teach TextNodeDumper to print the "implicit" bit for coroutine AST nodes

[hokein]

No description provided.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Haojian Wu (hokein)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/77311.diff

3 Files Affected:

• (modified) clang/include/clang/AST/TextNodeDumper.h (+2)
• (modified) clang/lib/AST/TextNodeDumper.cpp (+10)
• (added) clang/test/AST/ast-dump-coroutine.cpp (+46)

diff --git a/clang/include/clang/AST/TextNodeDumper.h b/clang/include/clang/AST/TextNodeDumper.h
index 2f4ed082a0c7ad..dd9ed56fc584a7 100644
--- a/clang/include/clang/AST/TextNodeDumper.h
+++ b/clang/include/clang/AST/TextNodeDumper.h
@@ -252,6 +252,8 @@ class TextNodeDumper
   void VisitGotoStmt(const GotoStmt *Node);
   void VisitCaseStmt(const CaseStmt *Node);
   void VisitReturnStmt(const ReturnStmt *Node);
+  void VisitCoawaitExpr(const CoawaitExpr* Node);
+  void VisitCoreturnStmt(const CoreturnStmt *Node);
   void VisitCompoundStmt(const CompoundStmt *Node);
   void VisitConstantExpr(const ConstantExpr *Node);
   void VisitCallExpr(const CallExpr *Node);
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index e8274fcd5cfe9c..d53688ea862e34 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -1094,6 +1094,16 @@ void clang::TextNodeDumper::VisitReturnStmt(const ReturnStmt *Node) {
   }
 }
 
+void clang::TextNodeDumper::VisitCoawaitExpr(const CoawaitExpr* Node) {
+  if (Node->isImplicit())
+    OS << " implicit";
+}
+
+void clang::TextNodeDumper::VisitCoreturnStmt(const CoreturnStmt *Node) {
+  if (Node->isImplicit())
+    OS << " implicit";
+}
+
 void TextNodeDumper::VisitConstantExpr(const ConstantExpr *Node) {
   if (Node->hasAPValueResult())
     AddChild("value",
diff --git a/clang/test/AST/ast-dump-coroutine.cpp b/clang/test/AST/ast-dump-coroutine.cpp
new file mode 100644
index 00000000000000..f760809f53689a
--- /dev/null
+++ b/clang/test/AST/ast-dump-coroutine.cpp
@@ -0,0 +1,46 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -std=c++20 \
+// RUN:    -fsyntax-only -ast-dump -ast-dump-filter test | FileCheck %s
+
+#include "Inputs/std-coroutine.h"
+
+using namespace std;
+
+struct Task {
+  struct promise_type {
+    std::suspend_always initial_suspend() { return {}; }
+    Task get_return_object() {
+      return std::coroutine_handle<promise_type>::from_promise(*this);
+    }
+    std::suspend_always final_suspend() noexcept { return {}; }
+    std::suspend_always return_void() { return {}; }
+    void unhandled_exception() {}
+
+    auto await_transform(int s) {
+      struct awaiter {
+        promise_type *promise;
+        bool await_ready() { return true; }
+        int await_resume() { return 1; }
+        void await_suspend(std::coroutine_handle<>) {}
+      };
+
+      return awaiter{this};
+    }
+  };
+
+  Task(std::coroutine_handle<promise_type> promise);
+
+  std::coroutine_handle<promise_type> handle;
+};
+
+// Verify the implicit AST nodes for coroutines.
+Task test()  {
+  co_await 1;
+}
+// CHECK:        |-DeclStmt {{.*}}
+// CHECK-NEXT:   | `-VarDecl {{.*}} implicit used __promise
+// CHECK-NEXT:   |   `-CXXConstructExpr {{.*}}
+// CHECK-NEXT:   |-ExprWithCleanups {{.*}} 'void'
+// CHECK-NEXT:   | `-CoawaitExpr {{.*}} 'void' implicit
+//                 ...
+// FIXME: the CoreturnStmt should be marked as implicit
+// CHECK: CoreturnStmt {{.*}} <col:6>

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[ilya-biryukov]

LGTM, other nodes also do this.
But please take a look at suggestions for improving the test before landing.

[ilya-biryukov]

Is this node implicit for initial suspend, for a call to await_transform or both? It would be useful to clarify by matching some child nodes or the dump of CoawaitExpr itself.

Also, could you add matching for both implicit and non-implicit co_await and co_return instances to show that the bit does not incidentally gets set/unset all the time?

Fixing CoreturnStmt in a follow-up does make a lot of sense!

[hokein]

Is this node implicit for initial suspend, for a call to await_transform or both?

This implicit node is just for initial suspend, it is the InitSuspend substmt of the CoroutineBodyStmt.

Added some more tests and matches for the written co_await and co_return statements.