bad error message on incorrect string literal

[llvmbot]

Bugzilla Link	17705
Version	3.2
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@DougGregor

Extended Description

linefeed should not be printed inside quotes. Instead error should be something like "invalid newline character in raw string delimiter".

5.cpp:1:21: error: invalid character '
' character in raw string delimiter; use PREFIX( )PREFIX to delimit raw string
char const* a = R"";
                    ^
5.cpp:1:17: error: expected expression
char const* a = R"";
                ^
2 errors generated.

[shafik]

reproducer: https://godbolt.org/z/9o8Gxavjr

char const* a = R"
";

[shafik]

The diagnostic is err_invalid_char_raw_delim

We issue it here:

llvm-project/clang/lib/Lex/Lexer.cpp

Lines 2229 to 2230 in 074630e

	Diag(PrefixEnd, diag::err_invalid_char_raw_delim)
	<< StringRef(PrefixEnd, 1);

I think a simple check for newline and maybe add a new diagnostic for this case invalid newline ....

[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. In the comments of the issue, request for it to be assigned to you.
2. Fix the issue locally.
3. 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.
4. Create a Git commit.
5. Run git clang-format HEAD~1 to format your changes.
6. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation.

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: None (llvmbot)

| | | | --- | --- | | Bugzilla Link | [17705](https://llvm.org/bz17705) | | Version | 3.2 | | OS | Linux | | Reporter | LLVM Bugzilla Contributor | | CC | @DougGregor |

Extended Description

linefeed should not be printed inside quotes. Instead error should be something like "invalid newline character in raw string delimiter".

5.cpp:1:21: error: invalid character '
' character in raw string delimiter; use PREFIX( )PREFIX to delimit raw string
char const* a = R"";
                    ^
5.cpp:1:17: error: expected expression
char const* a = R"";
                ^
2 errors generated.

[akshaykumars614]

@shafik, I will start analysing the issue.

[EugeneZelenko]

Not merged yet.