Re: [PATCH] lex: accept zero codepoints in strings

[Philip Herron <philip.herron@embecosm.com>]

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On 07/08/2021 16:45, Mark Wielaard wrote:
> Zero characters (codepoints) are acceptable in strings. The current
> Lexer::parse_string skipped such zero codepoints by accidents. The
> zero codepoint was also used as error/skip indicator, but that is only
> true if the third argument of utf8_escape_pair is true (yes, it is
> called pair, but is a triple).
>
> Add a testcase that checks the (sub)strings are separated by zero
> chars. Since we cannot slice strings yet this uses extern "C"
> functions, printf and memchr.
> ---
>
> On irc bjorn3_gh pointed out that our lexer ate embedded zero chars
> from strings. This fixes that issue and adds a testcase. Also on
> https://code.wildebeest.org/git/user/mjw/gccrs/commit/?h=str-zero
>
>  gcc/rust/lex/rust-lex.cc                      |  2 +-
>  .../rust/execute/torture/str-zero.rs          | 26 +++++++++++++++++++
>  2 files changed, 27 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/rust/execute/torture/str-zero.rs
>
> diff --git a/gcc/rust/lex/rust-lex.cc b/gcc/rust/lex/rust-lex.cc
> index 0b8a8eae651..2cfbc4fb1f4 100644
> --- a/gcc/rust/lex/rust-lex.cc
> +++ b/gcc/rust/lex/rust-lex.cc
> @@ -1827,7 +1827,7 @@ Lexer::parse_string (Location loc)
>  	  else
>  	    length += std::get<1> (utf8_escape_pair);
>  
> -	  if (current_char32 != Codepoint (0))
> +	  if (current_char32 != Codepoint (0) || !std::get<2> (utf8_escape_pair))
>  	    str += current_char32;
>  
>  	  // required as parsing utf8 escape only changes current_char
> diff --git a/gcc/testsuite/rust/execute/torture/str-zero.rs b/gcc/testsuite/rust/execute/torture/str-zero.rs
> new file mode 100644
> index 00000000000..e7fba0d1372
> --- /dev/null
> +++ b/gcc/testsuite/rust/execute/torture/str-zero.rs
> @@ -0,0 +1,26 @@
> +/* { dg-output "bar foo baz foobar\n" } */
> +extern "C"
> +{
> +  fn printf(s: *const i8, ...);
> +  fn memchr(s: *const i8, c: u8, n: usize) -> *const i8;
> +}
> +
> +pub fn main () -> i32
> +{
> +  let f = "%s %s %s %s\n\0";
> +  let s = "bar\0\
> +           foo\
> +           \x00\
> +           baz\u{0000}\
> +           foobar\0";
> +  let cf = f as *const str as *const i8;
> +  let cs = s as *const str as *const i8;
> +  unsafe
> +    {
> +      let cs2 = memchr (cs, b'f', 5);
> +      let cs3 = memchr (cs2, b'b', 5);
> +      let cs4 = memchr (cs3, b'f', 5);
> +      printf (cf, cs, cs2, cs3, cs4);
> +    }
> +  0
> +}

Hi Mark,

This patch looks good to go but the clang-format check is failing:
https://github.com/Rust-GCC/gccrs/pull/615

The error seems to be that it moves the extra check onto a new line.
https://github.com/Rust-GCC/gccrs/pull/615/checks?check_run_id=3272823975

Thanks

--Phil



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