[DTrace-devel] [PATCH] lexer: support // comments
Eugene Loh
eugene.loh at oracle.com
Wed Jul 23 01:18:16 UTC 2025
1) s/commens/comment/
2) Am I doing something wrong with this patch?
$ cat x.d
/*
* // is this okay?
*/
BEGIN {
exit(0);
}
I get stuff like:
/*/encountered inside a line comment
Frankly, I don't get as far as this script; I first hit such problems
with all the copyright notices we have in D files -- that
"http://oss...." stuff:
/*
* Oracle Linux DTrace.
* Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights
reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
3) Where do all the rules in this patch (tested by err.*) come from?
E.g., C seems more lenient:
$ cat x.c
// /* hello */
// comment /*
// comment //
int main(int c, char **v) {
/*
* //
*/
return 0;
}
$ gcc x.c
$ echo $?
0
On 7/22/25 18:12, Kris Van Hees via DTrace-devel wrote:
> Suggested-by: Ruud van der Pas <ruud.vanderpas at oracle.com>
> Suggested-by: Alan Maguire <alan.maguire at oracle.com>
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
> libdtrace/dt_lex.l | 14 +++++++++++++-
> .../lexer/err.D_SYNTAX.boc-in-line-comment.d | 16 ++++++++++++++++
> .../lexer/err.D_SYNTAX.boc-in-line-comment.r | 2 ++
> .../lexer/err.D_SYNTAX.eoc-in-line-comment.d | 16 ++++++++++++++++
> .../lexer/err.D_SYNTAX.eoc-in-line-comment.r | 2 ++
> .../lexer/err.D_SYNTAX.eof-in-line-comment.d | 16 ++++++++++++++++
> .../lexer/err.D_SYNTAX.eof-in-line-comment.r | 2 ++
> .../lexer/err.D_SYNTAX.lc-in-line-comment.d | 16 ++++++++++++++++
> .../lexer/err.D_SYNTAX.lc-in-line-comment.r | 2 ++
> test/unittest/lexer/tst.line-comment.d | 16 ++++++++++++++++
> test/unittest/lexer/tst.line-comment.r | 5 +++++
> 11 files changed, 106 insertions(+), 1 deletion(-)
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.d
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.r
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.d
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.r
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.d
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.r
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.d
> create mode 100644 test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.r
> create mode 100644 test/unittest/lexer/tst.line-comment.d
> create mode 100644 test/unittest/lexer/tst.line-comment.r
>
> diff --git a/libdtrace/dt_lex.l b/libdtrace/dt_lex.l
> index 9d502912..a7234800 100644
> --- a/libdtrace/dt_lex.l
> +++ b/libdtrace/dt_lex.l
> @@ -35,6 +35,7 @@ int yydebug;
> * S2 - D program outer scope (probe specifiers and declarations)
> * S3 - D control line parsing (i.e. after ^# is seen but before \n)
> * S4 - D control line scan (locate control directives only and invoke S3)
> + * S5 - D line comments (i.e. skip everything until end of line)
> * SIDENT - identifiers and comments only (after -> and .). (We switch to
> * SIDENT only from state S0: changing this would require new code
> * to track the state to switch back to.)
> @@ -46,7 +47,7 @@ int yydebug;
> %n 600 /* maximum states */
> %option yylineno
>
> -%s S0 S1 S2 S3 S4 SIDENT
> +%s S0 S1 S2 S3 S4 S5 SIDENT
>
> RGX_AGG "@"[a-zA-Z_][0-9a-zA-Z_]*
> RGX_PSPEC [-$:a-zA-Z_.?*\\\[\]!][-$:0-9a-zA-Z_.`?*\\\[\]!]*
> @@ -408,6 +409,11 @@ if (yypcb->pcb_token != 0) {
> BEGIN(S1);
> }
>
> +<S0,S2,SIDENT>"//" {
> + yypcb->pcb_cstate = (YYSTATE);
> + BEGIN(S5);
> + }
> +
> <S0>^{RGX_INTERP} |
> <S2>^{RGX_INTERP} ; /* discard any #! lines */
>
> @@ -548,6 +554,12 @@ if (yypcb->pcb_token != 0) {
> <S1>.|\n ; /* discard */
> <S1><<EOF>> yyerror("end-of-file encountered before matching */\n");
>
> +<S1>"/*" yyerror("/* encountered inside a line comment\n");
> +<S1>"*/" yyerror("*/ encountered inside a line comment\n");
> +<S1>"//" yyerror("/*/encountered inside a line comment\n");
> +<S5>\n BEGIN(yypcb->pcb_cstate);
> +<S5>. ; /* discard */
> +
> <S2>{RGX_PSPEC} {
> /*
> * S2 has an ambiguity because RGX_PSPEC includes '*'
> diff --git a/test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.d b/test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.d
> new file mode 100644
> index 00000000..61f5961f
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.d
> @@ -0,0 +1,16 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: Line comments cannot contain begin-of-comment markers.
> + */
> +
> +// Comment /*
> +BEGIN
> +{
> + exit(0);
> +}
> diff --git a/test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.r b/test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.r
> new file mode 100644
> index 00000000..74d1d0ef
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.r
> @@ -0,0 +1,2 @@
> +-- @@stderr --
> +dtrace: failed to compile script test/unittest/lexer/err.D_SYNTAX.boc-in-line-comment.d: [D_SYNTAX] line 12: /* encountered inside a line comment
> diff --git a/test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.d b/test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.d
> new file mode 100644
> index 00000000..8fe2ff04
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.d
> @@ -0,0 +1,16 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: Line comments cannot contain end-of-comment markers.
> + */
> +
> +// Comment */
> +BEGIN
> +{
> + exit(0);
> +}
> diff --git a/test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.r b/test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.r
> new file mode 100644
> index 00000000..64d5ae63
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.r
> @@ -0,0 +1,2 @@
> +-- @@stderr --
> +dtrace: failed to compile script test/unittest/lexer/err.D_SYNTAX.eoc-in-line-comment.d: [D_SYNTAX] line 12: */ encountered inside a line comment
> diff --git a/test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.d b/test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.d
> new file mode 100644
> index 00000000..a9207693
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.d
> @@ -0,0 +1,16 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: End-of-file in a line comment is an error.
> + */
> +
> +BEGIN
> +{
> + exit(0);
> +}
> +// Comment
> \ No newline at end of file
> diff --git a/test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.r b/test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.r
> new file mode 100644
> index 00000000..f46fce3e
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.r
> @@ -0,0 +1,2 @@
> +-- @@stderr --
> +dtrace: failed to compile script test/unittest/lexer/err.D_SYNTAX.eof-in-line-comment.d: [D_SYNTAX] line 16: end-of-file encountered in line comment
> diff --git a/test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.d b/test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.d
> new file mode 100644
> index 00000000..0332e1ae
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.d
> @@ -0,0 +1,16 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: Line comments cannot contain a line commens marker.
> + */
> +
> +// Comment //
> +BEGIN
> +{
> + exit(0);
> +}
> diff --git a/test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.r b/test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.r
> new file mode 100644
> index 00000000..d1152afc
> --- /dev/null
> +++ b/test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.r
> @@ -0,0 +1,2 @@
> +-- @@stderr --
> +dtrace: failed to compile script test/unittest/lexer/err.D_SYNTAX.lc-in-line-comment.d: [D_SYNTAX] line 12: // encountered inside a line comment
> diff --git a/test/unittest/lexer/tst.line-comment.d b/test/unittest/lexer/tst.line-comment.d
> new file mode 100644
> index 00000000..4deb66f4
> --- /dev/null
> +++ b/test/unittest/lexer/tst.line-comment.d
> @@ -0,0 +1,16 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: // comments are supported.
> + */
> +
> +// exit(1);
> +BEGIN // exit(1);
> +{ // exit(1);
> + exit(0); // exit(1);
> +} // exit(1);
> diff --git a/test/unittest/lexer/tst.line-comment.r b/test/unittest/lexer/tst.line-comment.r
> new file mode 100644
> index 00000000..d4e4c325
> --- /dev/null
> +++ b/test/unittest/lexer/tst.line-comment.r
> @@ -0,0 +1,5 @@
> + FUNCTION:NAME
> + :BEGIN
> +
> +-- @@stderr --
> +dtrace: script 'test/unittest/lexer/tst.line-comment.d' matched 1 probe
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