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bug#17681: 24.3.91; "Arithmetic Error" in hide-ifdef mode when using shi
From: |
David Engster |
Subject: |
bug#17681: 24.3.91; "Arithmetic Error" in hide-ifdef mode when using shift operators |
Date: |
Tue, 03 Jun 2014 21:12:33 +0200 |
Recipe:
- Create a file "test.h" containing the following (this is from
the file 'jiffies.h' in the Linux kernel):
#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000)
#endif
- emacs -Q
- Load the file, activate hide-ifdef-mode
- C-c @ h (hide-ifdefs)
The minibuffer will show "Arithmetic Error". Here is the backtrace:
Debugger entered--Lisp error: (arith-error)
hif-divide(0 nil)
(hif-shiftleft (hif-divide (hif-shiftleft (hif-lookup (quote NSEC_PER_SEC))
2) (hif-lookup (quote TICK_NSEC))) (hif-minus (hif-lookup (quote
SEC_JIFFIE_SC)) 2))
(hif-logand (hif-shiftleft (hif-divide (hif-shiftleft (hif-lookup (quote
NSEC_PER_SEC)) 2) (hif-lookup (quote TICK_NSEC))) (hif-minus (hif-lookup (quote
SEC_JIFFIE_SC)) 2)) 2147483648.0)
(hif-not (hif-logand (hif-shiftleft (hif-divide (hif-shiftleft (hif-lookup
(quote NSEC_PER_SEC)) 2) (hif-lookup (quote TICK_NSEC))) (hif-minus (hif-lookup
(quote SEC_JIFFIE_SC)) 2)) 2147483648.0))
eval((hif-not (hif-logand (hif-shiftleft (hif-divide (hif-shiftleft
(hif-lookup (quote NSEC_PER_SEC)) 2) (hif-lookup (quote TICK_NSEC))) (hif-minus
(hif-lookup (quote SEC_JIFFIE_SC)) 2)) 2147483648.0)))
hif-possibly-hide()
hide-ifdef-guts()
hide-ifdefs()
Earlier Emacsen did not throw an error here (although it is very
possible that the above line wasn't calculated correctly). Still, this
probably qualifies as a regression.
-David
- bug#17681: 24.3.91; "Arithmetic Error" in hide-ifdef mode when using shift operators,
David Engster <=