[cmake-developers] [CMake 0011392]: find_package does not support relative paths

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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http://www.cmake.org/Bug/view.php?id=11392 
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Reported By:                Derek Bruening
Assigned To:                
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Project:                    CMake
Issue ID:                   11392
Category:                   CMake
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     new
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Date Submitted:             2010-11-02 11:48 EDT
Last Modified:              2010-11-02 11:48 EDT
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Summary:                    find_package does not support relative paths
Description: 
I have one CMake project ("drmemory") that uses another ("DynamoRIO") via
find_package, using a cache variable "DynamoRIO_DIR" to point at the
location of the DynamoRIO config file.  It is very natural to use a
relative path from the build dir at configure time for DynamoRIO_DIR.
However, this does not always work.

Try this on Linux with any CMake version (I've tried 2.6.4 and 2.8.0) and
you'll get a find_package failure on the config for drmemory:

mkdir test-dotdot
cd test-dotdot
svn checkout -r 474 http://dynamorio.googlecode.com/svn/trunk/ dynamorio
mkdir -p build-dynamorio/sub
cd build-dynamorio/sub
CXXFLAGS=-m32 CFLAGS=-m32 cmake -DBUILD_DOCS=OFF
-DCMAKE_INSTALL_PREFIX=../../exports ../../dynamorio && make -j4 install
cd ../..
svn checkout -r 75 http://drmemory.googlecode.com/svn/trunk/ drmemory
mkdir -p build-drmemory/sub
cd build-drmemory/sub
ls ../../exports/cmake
CXXFLAGS=-m32 CFLAGS=-m32 cmake -DDynamoRIO_DIR=../../exports/cmake
-DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=../../exports_drmemory
../../drmemory

I asked Brad King about this:

  By the time find_package runs it has no clue what the base path was
  for the relative path.  The best guess it has is the *source* tree
  containing the CMakeLists.txt that invoked it.  This behavior is
  meant for finding in-tree packages.

  We've never supported relative paths here.  The command line
  parser has no way to know that DynamoRIO_DIR is a path and not
  a string and therefore cannot do conversion to full path safely.
  Someday we will have a way to map options like --prefix= to cache
  definitions that have types.  That mapping might be able to do this.

At the least, the find_package documentation should state that relative
paths are not supported, or what they are relative to.  My intuition says
that a relative path would be from the build dir.

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Issue History 
Date Modified    Username       Field                    Change               
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2010-11-02 11:48 Derek Bruening New Issue                                    
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