Since some of the tests inherently produce platform-specific results, we have provided a way to supply platform-specific result comparison files. Frequently, the same variation applies to multiple platforms; rather than supplying a separate comparison file for every platform, there is a mapping file that defines which comparison file to use. So, to eliminate bogus test "failures" for a particular platform, you must choose or make a variant result file, and then add a line to the mapping file, which is "resultmap".
Each line in the mapping file is of the form
testname/platformnamepattern=comparisonfilename
The test name is just the name of the particular regression
test module. The platform name pattern is a pattern in the style of
expr(1) (that is, a regular expression with an implicit ^ anchor at
the start). It is matched against the platform name as printed by
config.guess. The comparison file name is the name of the
substitute result comparison file.
For example: the int2 regress test includes a deliberate entry of a value that is too large to fit in int2. The specific error message that is produced is platform-dependent; our reference platform emits
ERROR: pg_atoi: error reading "100000": Numerical result out of range
but a fair number of other Unix platforms emit
ERROR: pg_atoi: error reading "100000": Result too large
Therefore, we provide a variant comparison file,
int2-too-large.out, that includes this spelling of the error
message. To silence the bogus "failure" message on HPPA platforms,
resultmap includes
int2/hppa=int2-too-large
which will trigger on any machine for which config.guess's
output begins with 'hppa'. Other lines in resultmap select the
variant comparison file for other platforms where it's appropriate.