libpng find_package broken

[sjdrc]

Describe the bug
When installing libpng and attempting to use through cmake, I get the error in the log section below.

Package installed correctly and I followed the instructions it gave:

The package libpng:x64-linux provides CMake targets:

    find_package(libpng CONFIG REQUIRED)
    target_link_libraries(main PRIVATE png_static)

Environment

• OS: Ubuntu 18.04
• Compiler: gcc 7.4.0/cmake 3.14.3

To Reproduce
Steps to reproduce the behavior:

1. ./vcpkg install libpng
2. In my project's CMakeLists.txt do find_package(libpng CONFIG REQUIRED)

Expected behavior
I should be able to find libpng with find_package

Failure logs

CMake Error at /home/sebastien/.ezvcpkg/2019.07/scripts/buildsystems/vcpkg.cmake:266 (_find_package):
  Could not find a package configuration file provided by "libpng" with any
  of the following names:

    libpngConfig.cmake
    libpng-config.cmake

  Add the installation prefix of "libpng" to CMAKE_PREFIX_PATH or set
  "libpng_DIR" to a directory containing one of the above files.  If "libpng"
  provides a separate development package or SDK, be sure it has been
  installed.

Additional context
vcpkg folder installed/x64-linux/share/libpng contains the following files:

libpng16.cmake
libpng16-debug.cmake
libpng16-release.cmake

Renaming to:

libpngConfig.cmake
libpngConfig-debug.cmake
libpngConfig-release.cmake

lets cmake find the package as expected.

[vicroms]

Hi @sjdrc

PR #7972 should fix this issue.

I will note, that the traditional way to include libpng is by using the built-in CMake module (call find_package(PNG REQUIRED) instead).

[sjdrc]

Ah right, if that is the case, should the The package libpng:x64-linux provides CMake targets: message recommend using find_package(PNG REQUIRED) instead?

[vicroms]

The message is auto-generated by vcpkg when config files are detected, in this case it can be overridden by providing a usage file.

However, once the PR is merged both find_package(libpng CONFIG) and find_package(PNG MODULE) will work.