MantisBT - CMake
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IDProjectCategoryView StatusDate SubmittedLast Update
0014721CMakeCMakepublic2014-01-27 11:002016-06-10 14:31
ReporterAndreas Mohr 
Assigned ToRobert Maynard 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionmoved 
PlatformPCOSLinuxOS VersionUbuntu LTS12.04
Product VersionCMake 2.8.12.1 
Target VersionFixed in Version 
Summary0014721: Ninja: warning message related to WriteUnknownExplicitDependencies() for CMakeCache.txt: file entry simply not supported yet??
DescriptionSee minimal test case below.

amoh@lxamoh9010:~/cmake_tests/ninja_cmakecache_txt/build$ ninja
ninja: warning: multiple rules generate CMakeCache.txt. builds involving this target will not be correct; continuing anyway
ninja: no work to do.


Ninja 1.4.0, using CMake trunk.
Steps To Reproducecmake_minimum_required(VERSION 2.8)

project(ninja_cmakecache_txt C)

# ...and add a default target to create a backup of CMakeCache.txt,
# since that file might get destroyed too easily (at least CMake 2.6.4
# will kill it on out-of-disk-space, resulting in complete abort of
# configuration run):
if(NOT TARGET master_backup_CMakeCache)
  # CMAKE_CACHEFILE_DIR defined when cache already existing only...
  if(DEFINED CMAKE_CACHEFILE_DIR)
    # Better reference specific CMAKE_CACHEFILE_DIR variable (same as CMAKE_BINARY_DIR).
    # Unfortunately there's no CMake file name variable for "CMakeCache.txt"
    # (source code of CMake always open-codes that name),
    # thus there's nothing to reference here.
    set(CMakeCache_file "${CMAKE_CACHEFILE_DIR}/CMakeCache.txt")
    set(CMakeCache_file_backup "${CMakeCache_file}.backup")
    add_custom_command(OUTPUT "${CMakeCache_file_backup}"
      # copy_if_different _not_ needed (target dependency needs remaking? --> _do_ copy!)
      COMMAND "${CMAKE_COMMAND}" -E copy "${CMakeCache_file}" "${CMakeCache_file_backup}"
      DEPENDS "${CMakeCache_file}"
      COMMENT "creating CMakeCache backup (${CMakeCache_file_backup})"
    )
    add_custom_target(master_backup_CMakeCache ALL DEPENDS "${CMakeCache_file_backup}")
  endif(DEFINED CMAKE_CACHEFILE_DIR)
endif(NOT TARGET master_backup_CMakeCache)

file(WRITE test1.c "int main() { return 1; }")
add_library(test1 SHARED test1.c)
Additional InformationWriteUnknownExplicitDependencies() seems to be the function responsible for creating/filtering out these parts.

Manually removing the part

# =============================================================================
# Unknown Build Time Dependencies.
# Tell Ninja that they may appear as side effects of build rules
# otherwise ordered by order-only dependencies.

build CMakeCache.txt: phony CMakeCache.txt


from build.ninja makes the warning message go away, in fact.


So tell me that WriteUnknownExplicitDependencies() handling simply failed to have CMakeCache.txt listed as a build-environment-related file?
Or perhaps my sample is completely invalid since there might be a problem? (read: "I don't know what I'm doing here" :)

Thanks,

Andreas Mohr
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Issue History
Date ModifiedUsernameFieldChange
2014-01-27 11:00Andreas MohrNew Issue
2014-01-27 11:08Brad KingAssigned To => Robert Maynard
2014-01-27 11:08Brad KingStatusnew => assigned
2016-06-10 14:29Kitware RobotNote Added: 0042470
2016-06-10 14:29Kitware RobotStatusassigned => resolved
2016-06-10 14:29Kitware RobotResolutionopen => moved
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0042470)
Kitware Robot   
2016-06-10 14:29   
Resolving issue as `moved`.

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