0000348: Failure of tests/general/string_format_special_floats with MSVC

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0000348

mercury

Bug

public

2014-07-18 15:07

2015-07-08 13:15

Reporter

juliensf

Assigned To

juliensf

Priority

normal

Severity

minor

Reproducibility

have not tried

Status

resolved

Resolution

fixed

Product Version

Target Version

Fixed in Version

Summary

0000348: Failure of tests/general/string_format_special_floats with MSVC

Description

When using MSVC as a C compiler, the test case tests/general/string_format_special_float fails as the MS libc doesn't appear to
implement the C99 behaviour for printing nan, inf etc.

With VS2012 we get:

Plus Infinity:
                  %e: failure '1.#INF00
                  %f: failure '1.#INF00
                  %g: failure '1.#INF'
                  %E: failure '1.#INF00
                  %F: failure ''
                  %G: failure '1.#INF'
Minus Infinity:
                  %e: failure '-1.#INF0
                  %f: failure '-1.#INF0
                  %g: failure '-1.#INF'
                  %E: failure '-1.#INF0
                  %F: failure ''
                  %G: failure '-1.#INF'
Not a number:
                  %e: failure '-1.#IND0
                  %f: failure '-1.#IND0
                  %g: failure '-1.#IND'
                  %E: failure '-1.#IND0
                  %F: failure ''
                  %G: failure '-1.#IND'

We should probably check for special float values before calling sprintf
and just handle them directly using Mercury. (This would also avoid some
inconsistencies in the output of these tests due to do differences in C
libraries.)

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Notes
~0000747 juliensf (administrator) 2014-07-18 15:46	The same problem also affects tests/hard_coded/write_float_special.

~0000748 wangp (developer) 2014-07-18 16:23	For what it's worth, NaNs were printed on AIX as "NaNQ", where 'Q' stands for quiet.

~0000750 juliensf (administrator) 2014-07-18 17:01	C99 says they should be printed as: nan, -nan, nan(...) or -nan(...) where "..." is an implementation-defined sequence of letters, digits or underscores. (Or in uppercase if %F is used.)

~0000755 juliensf (administrator) 2014-08-06 10:37	I intend to address this one by checking for, and handling, inf and nan (although nan should really cause an exception to be thrown) in Mercury rather than relying on sprintf. Even with C99 there are too many annoying little differences in how inf and nan are handled. Dealing with Java and C# just complicates things further.

~0000838 juliensf (administrator) 2015-07-08 13:15	Fixed in commit 4e15777.

Notes

Date Modified	Username	Field	Change
Issue History
2014-07-18 15:07	juliensf	New Issue
2014-07-18 15:46	juliensf	Note Added: 0000747
2014-07-18 16:23	wangp	Note Added: 0000748
2014-07-18 17:01	juliensf	Note Added: 0000750
2014-08-06 10:37	juliensf	Note Added: 0000755
2014-08-06 10:37	juliensf	Assigned To	=> juliensf
2014-08-06 10:37	juliensf	Status	new => assigned
2015-07-08 13:15	juliensf	Note Added: 0000838
2015-07-08 13:15	juliensf	Status	assigned => resolved
2015-07-08 13:15	juliensf	Resolution	open => fixed

Issue History