MantisBT - CMake
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IDProjectCategoryView StatusDate SubmittedLast Update
0013366CMakeCMakepublic2012-07-01 16:592012-12-03 07:46
ReporterJosh Faust 
Assigned ToPeter Kuemmel 
PrioritynormalSeveritymajorReproducibilityalways
StatusclosedResolutionfixed 
PlatformMicrosoftOSWindowsOS Version7
Product VersionCMake 2.8.8 
Target VersionFixed in Version 
Summary0013366: Ninja generator on windows does not take everything into account when checking the command line length limit
DescriptionWhen generating the ninja build files, on windows cmake will check the command line length and generate a response file if it's too long. It does this by checking the args and the build line passed to the ninja rule. This does not take into account, though, what the ninja rule actually expands to including any variables passed such as link flags, full executable path, etc.

CMake sets the command line limit to 8000 characters on windows, though the actual limit is 8192. I'm assuming it's set to 8000 because it's trying to account for the lack of these flags, but this is not always enough. In rare cases the build can still fail with a "The command line is too long." error.

In my specific case, these extra flags account for ~500 characters, while cmake only actually checks 0005058:0007700 characters -- and added together they're above the 8192 limit.

The quick fix seems to be changing the max command line to be shorter (say, 7000) in cmNinjaNormalTargetGenerator.cxx:483.

The real fix would be to retrieve the rule and expand all the variables in the command, which I do not see an easy way of doing after a quick look through the code.
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Issue History
Date ModifiedUsernameFieldChange
2012-07-01 16:59Josh FaustNew Issue
2012-07-01 18:14Peter KuemmelNote Added: 0029870
2012-07-02 03:02Josh FaustNote Added: 0029871
2012-07-02 04:37Peter KuemmelNote Added: 0029872
2012-07-02 12:54Bill HoffmanAssigned To => Peter Kuemmel
2012-07-02 12:54Bill HoffmanStatusnew => assigned
2012-07-03 05:44Peter KuemmelNote Added: 0029888
2012-07-03 05:44Peter KuemmelStatusassigned => resolved
2012-07-03 05:44Peter KuemmelResolutionopen => fixed
2012-12-03 07:46David ColeNote Added: 0031814
2012-12-03 07:46David ColeStatusresolved => closed

Notes
(0029870)
Peter Kuemmel   
2012-07-01 18:14   
Yes, I thought 8000 would be enough and other cases are "esoteric", but it seems this was wrong.

The variables used by the rule are also written there:

build build\bin\kst2d.exe: CXX_EXECUTABLE_LINKER src\kst\CMakeFiles\kst2.dir ...
  FLAGS = /DWIN32 /D_WINDOWS /W3 ,,,
  LINK_FLAGS = /STACK:10000000 /machine:X86 ...
  LINK_LIBRARIES = E:\sandbox\qt\_4.8_zehner\lib\qtmaind.lib ...
  POST_BUILD = cd .
  PRE_LINK = cd .
  TARGET_IMPLIB = src\kst\kst2d.lib
  TARGET_PDB = build\bin\kst2d.pdb

so we could simply consider the length of all the variable assignments.

I've pushed a fix to next.
(0029871)
Josh Faust   
2012-07-02 03:02   
That's still not quite exact, as there's still the overhead from the rule itself, e.g.:

$PRE_LINK && C:\Users\josh\packages\cmake\build\bin\Release\cmake.exe -E vs_link_dll c:\PROGRA~2\MICROS~2.0\VC\bin\link.exe /nologo $in /out:$out /implib:$TARGET_IMPLIB /pdb:$TARGET_PDB /dll /version:0.0 $LINK_FLAGS $LINK_LIBRARIES && $POST_BUILD

has about 170 non-variable characters in it. To be safe you may still want to up the 192 character buffer.

Your change does fix my use case though, thanks! Not sure what the policy here is, should I close this ticket? Actually, can I even do that? I don't see any way for me to edit the ticket.
(0029872)
Peter Kuemmel   
2012-07-02 04:37   
OK, also the length of the command line is used.

It is still not 100% perfect because you could write
rules which use a variable multiple times. But I think
such cases then are really "esoteric".

I also could only write comments here, I assume the
release manager will close it.
(0029888)
Peter Kuemmel   
2012-07-03 05:44   
On 02.07.2012 17:40, Bill Hoffman wrote:
>
> Can we just put the link step into the response files?
>
The code now catches nearly all cases. I don't think
it will fail in any real-live usage.
(0031814)
David Cole   
2012-12-03 07:46   
Closing resolved issues that have not been updated in more than 4 months.