Date: Mon, 20 Mar 2023 19:14:25 +0000 From: bugzilla-noreply@freebsd.org To: dtrace@FreeBSD.org Subject: [Bug 269906] dtrace requires empty expression to print anything from matching search Message-ID: <bug-269906-32976-TLmhN1esIS@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-269906-32976@https.bugs.freebsd.org/bugzilla/> References: <bug-269906-32976@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D269906 --- Comment #5 from Christos Margiolis <christos@margiolis.net> --- Apparently, this patch doesn't really work and, in fact, allowing a predica= te with no acts is probably impossible in D without introducing a significant amount of complexity. awk can do that just fine because awk's predicates ca= nnot contain unescaped "/", since it searches for regexes. D on the other hand allows normal computation inside the predicate, meaning one can do division inside it: kinst::vm_fault: /(cpu / 2) =3D=3D 1/ This is a problem because the D lexer considers "/" to be a division token = (and not a start/end of predicate token) when the next non-whitespace character coming after it is anything other than EOF, 0, ;, { and }, so if we try and run: kinst::vm_fault: /cpu =3D=3D 1/ fbt::malloc:entry The lexer will think the end of predicate is actually a division token beca= use the succeeding non-whitespace character "f" doesn't match the character set that indicate the end of predicate. --=20 You are receiving this mail because: You are the assignee for the bug.=
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