65 lines
2.3 KiB
Plaintext
65 lines
2.3 KiB
Plaintext
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Copyright (C) 1992, 1995, 1998, 2001, 2006, 2007, 2010, 2011, 2015, 2019
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Free Software Foundation, Inc.
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Copying and distribution of this file, with or without modification,
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are permitted in any medium without royalty provided the copyright
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notice and this notice are preserved.
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--------------------------------------------------------------------------
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Sun Apr 21 14:27:19 IDT 2019
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============================
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This file documents several things related to the 2008 POSIX standard
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that I noted after reviewing it.
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1. POSIX leaves undefined what happens for something like
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awk '{ print ; exit }' if=42 /etc/passwd
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Mawk diagnoses this. Gawk and BWK awk do not. This doesn't seem to be
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worth the effort to add the code, but at least I'm aware of it.
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2. The 2001-2004 standards accidentally required support for hexadecimal
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floating point constants and for Infinity and Not-A-Number (NaN) values.
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The 2008 standard now explicitly allows, but does not require, such
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support.
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More discussion is provided in the node `POSIX Floating Point Problems'
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in gawk.texi.
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3. String comparison with <, <= etc is supposed to take the locale's collating
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sequence into account. By default gawk doesn't do this. Rather, gawk
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will do this only if --posix is in effect.
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4. According to POSIX, the function parameters of one function may not have
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the same name as another function, making this invalid:
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function foo() { ... }
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function bar(foo) { ...}
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Or even:
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function bar(foo) { ...}
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function foo() { ... }
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Gawk enforces this only with --posix.
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5. According to POSIX (following the A, K, & W book), when RS = "", then
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newline is also a separator, "no matter what the value of FS is", implying
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that this is true even if FS is a regexp.
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In fact, UNIX awk has never behaved that, way; it adds \n to the list
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for FS = " " or any other single character, and gawk does too. This is
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essentially a bug in POSIX.
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The following things aren't described by POSIX but ought to be:
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1. The value of $0 in an END rule
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2. The return value of a function that either does return with no value
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or that falls off the end of the function body.
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3. What happens with substr() if start is <= 0, or greater than the length
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of the string, or if length is <= 0.
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4. Whether "next" can be invoked from a function body.
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