Undesired AST printout for PackIndexingExpr

[zyn0217]

Given

template <class... T, unsigned N>
auto foo(T ...params) {
  return params...[N];
}

Running clang -std=c++2c -fsyntax-only -Xclang -ast-print on it results in

template <class ...T, unsigned int N> auto foo(T ...params) {
    return 0xd3cffc0...[0xd3cffe0];
}

https://compiler-explorer.com/z/czchqqj1s

The cause is due to the inadvertent use of operator << in clang/lib/AST/StmtPrinter.cpp:

llvm-project/clang/lib/AST/StmtPrinter.cpp

Lines 2519 to 2521 in e508bac

	void StmtPrinter::VisitPackIndexingExpr(PackIndexingExpr *E) {
	OS << E->getPackIdExpression() << "...[" << E->getIndexExpr() << "]";
	}

Any PackIndexingExpr would be printed as their addresses rather than intelligible source codes, contrary to the behavior for any other expressions.

We should use PrintExpr() anyway.

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Younan Zhang (zyn0217)

Given

template <class... T, unsigned N>
auto foo() {
  return T...[N];
}

Running clang -std=c++2c -fsyntax-only -Xclang -ast-print on it results in

template <class ...T, unsigned int N> auto foo(T ...params) {
    return 0xd3cffc0...[0xd3cffe0];
}

https://compiler-explorer.com/z/czchqqj1s

The cause is due to the inadvertent use of operator << in clang/lib/AST/StmtPrinter.cpp:

llvm-project/clang/lib/AST/StmtPrinter.cpp

Lines 2519 to 2521 in e508bac

	void StmtPrinter::VisitPackIndexingExpr(PackIndexingExpr *E) {
	OS << E->getPackIdExpression() << "...[" << E->getIndexExpr() << "]";
	}

Any PackIndexingExpr would be printed as their addresses rather than intelligible source codes, contrary to the behavior for any other expressions.

We should use PrintExpr() anyway.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Younan Zhang (zyn0217)

Given

template <class... T, unsigned N>
auto foo() {
  return T...[N];
}

Running clang -std=c++2c -fsyntax-only -Xclang -ast-print on it results in

template <class ...T, unsigned int N> auto foo(T ...params) {
    return 0xd3cffc0...[0xd3cffe0];
}

https://compiler-explorer.com/z/czchqqj1s

The cause is due to the inadvertent use of operator << in clang/lib/AST/StmtPrinter.cpp:

llvm-project/clang/lib/AST/StmtPrinter.cpp

Lines 2519 to 2521 in e508bac

	void StmtPrinter::VisitPackIndexingExpr(PackIndexingExpr *E) {
	OS << E->getPackIdExpression() << "...[" << E->getIndexExpr() << "]";
	}

Any PackIndexingExpr would be printed as their addresses rather than intelligible source codes, contrary to the behavior for any other expressions.

We should use PrintExpr() anyway.

[kmr-srbh]

Hello! I am new to the LLVM codebase. I would love to work on this issue. Could I be assigned this?

[zyn0217]

@kmr-srbh Here it is. Happy hacking!