[llvm-dev] Prevent ninja from rerunning cmake in a new build directory

[Don Hinton via llvm-dev]

The ninja developers want to fix this in a more elegant way, which
unfortunately will also require a change to cmake.  So, if you'd rather not
wait, or like me, can't upgrade cmake, you can use my fork here:
https://github.com/donhinton/ninja

hth...
don

On Fri, May 24, 2019 at 2:49 PM Don Hinton <hintonda at gmail.com> wrote:

> Please find a better fix here:
> https://github.com/ninja-build/ninja/pull/1580/commits/9221541695206b7e7e89f9b8743d8eae56634999
>
>
> On Fri, May 24, 2019 at 11:36 AM Don Hinton <hintonda at gmail.com> wrote:
>
>> Just posted this fix on ninja's github page, but figured I'd share it
>> with a larger audience.
>>
>> Every time I run cmake && ninja in a new build directory, ninja will
>> rerun cmake because the entry for build.ninja in .ninja_log is older than
>> the timestamp on CMakeCache.txt, even if the timestamps on the actual file
>> isn't older.
>>
>> The following patch fixes the problem, i.e., there's no need to add
>> build.ninja to the ninja_log:
>>
>> diff --git a/src/ninja.cc b/src/ninja.cc
>> index a093cd1..810b22d 100644
>> --- a/src/ninja.cc
>> +++ b/src/ninja.cc
>> @@ -249,8 +249,6 @@ bool NinjaMain::RebuildManifest(const char* input_file, string* err) {
>>      return false;
>>
>>    Builder builder(&state_, config_, &build_log_, &deps_log_, &disk_interface_);
>> -  if (!builder.AddTarget(node, err))
>> -    return false;
>>
>>    if (builder.AlreadyUpToDate())
>>      return false;  // Not an error, but we didn't rebuild.
>>
>>
>> hth...
>> don
>>
>
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