test cases/common/234: get limit right on linux, generate fewer files

test cases/common/234 very long commmand line/meson.build

@@ -1,6 +1,29 @@
 project('very long command lines', 'c')
 
-seq = run_command('seq.py', '1', '256').stdout().strip().split('\n')
+# Get the current system's commandline length limit.
+if build_machine.system() == 'windows'
+  # Various limits on windows:
+  # cmd.exe: 8kb
+  # CreateProcess: 32kb
+  limit = 32767
+elif build_machine.system() == 'cygwin'
+  # cygwin-to-win32: see above
+  # cygwin-to-cygwin: no limit?
+  # Cygwin is slow, so only test it lightly here.
+  limit = 8192
+else
+  # ninja passes whole line as a single argument, for which
+  # the limit is 128k as of Linux 2.6.23.  See MAX_ARG_STRLEN.
+  # BSD seems similar, see https://www.in-ulm.de/~mascheck/various/argmax
+  limit = 131072
+endif
+# Now exceed that limit, but not so far that the test takes too long.
+name = 'ALongFilenameMuchLongerThanIsNormallySeenAndReallyHardToReadThroughToTheEndAMooseOnceBitMySisterSheNowWorksAtLLamaFreshFarmsThisHasToBeSoLongThatWeExceed128KBWithoutCompilingTooManyFiles'
+namelen = 187
+nfiles = 50 + limit / namelen
+message('Expected link commandline length is approximately ' + '@0@'.format((nfiles * (namelen+28))))
+
+seq = run_command('seq.py', '1', '@0@'.format(nfiles)).stdout().strip().split('\n')
 
 sources = []
 codegen = find_program('codegen.py')
@@ -8,7 +31,7 @@ codegen = find_program('codegen.py')
 foreach i : seq
   sources += custom_target('codegen' + i,
                            command: [codegen, i, '@OUTPUT@'],
-                           output: 'test' + i + '.c')
+                           output: name + i + '.c')
 endforeach
 
 shared_library('sharedlib', sources)