[cmake-developers] Bad error message when a package could not be found - make find_package() not search config files by default

[Rolf Eike Beer]

> On Thursday 16 February 2012, Alexander Neundorf wrote:
>> Hi,
>>
>> when I use a Find-module to search for a package, I get a nice error
>> message if the package could not be found.
>
> I collected the various error messages which can be produced in the
> different
> cases:
> * package not found
> * package found, but version doesn't match
>
> * REQUIRED
> * without REQUIRED
>
> * find_package() with no Find-module present
> * find_package(NO_MODULE)
> * find_package() with a wrapper Find-module which does:
>      find_package(ecm QUIET NO_MODULE)
>      fphsa(ecm CONFIG_MODE)
>
>
> Here we go:
>
> package not found, REQUIRED:
>
> --------------------------------------------------------
> 1.) find_package() with no Find-module present:
>
> CMake Error at CMakeLists.txt:4 (find_package):
>   Could not find module Findecm.cmake or a configuration file
>   for package ecm.
>
>   Adjust CMAKE_MODULE_PATH to find Findecm.cmake or set
>   ecm_DIR to the directory containing a CMake configuration
>   file for ecm.  The file will have one of the following
>   names:
>
>     ecmConfig.cmake
>     ecm-config.cmake
> ***** processing continues, but with error
>
>
> --------------------------------------------------------
> 2.) find_package(NO_MODULE):
>
> CMake Error at CMakeLists.txt:4 (find_package):
>   Could not find a configuration file for package ecm.
>
>   Set ecm_DIR to the directory containing a CMake
>   configuration file for ecm.  The file will have one of the
>   following names:
>
>     ecmConfig.cmake
>     ecm-config.cmake
> ***** processing continues, but with error

> --------------------------------------------------------
> 4.) find_package() with no Find-module present, same with NO_MODULE:
>
> CMake Error at CMakeLists.txt:4 (find_package):
>   Could not find a configuration file for package "ecm" that
>   is compatible with requested version "0.0.4".
>
>   The following configuration files were considered but not accepted:
>
>     /opt/ecm/share/ecm-0.0.2/cmake/ecm-config.cmake, version: 0.0.2
>     /opt/ecm/share/ecm-0.0.3/cmake/ecm-config.cmake, version: 0.0.3
> ***** processing continues, but with error

> What should be improved:
> 1.), 2.), 4.)  processing should stop if REQUIRED was used

I disagree. Say I want to build $random package. Throw the source
somewhere, run cmake. Now I see the errors and install the packages that
are missing. If processing immediately stops on an unmet dependency I
would have to repeat that as long as there are unmet dependencies. If
processing continues but gives and error I can install all things at once.

Eike