cmake find_package脚本只能在Linux上失败

Question

我为Stanford Network Analysis Platform（SNAP）编写了一个包查找模块，它在macOS上按预期工作但在Linux上失败，由于某种原因，尽管显然找不到相关的路径/文件，但它报告没有找到Snap。

FindSnap.cmake：

include(FindPackageHandleStandardArgs)
set(Snap_ROOT_DIR $ENV{WORKSPACE_ROOT}/opt/Snap)
message(STATUS "Snap_ROOT_DIR: " ${Snap_ROOT_DIR})

find_path(Snap_CORE
        NAMES "Snap.h"
        PATH_SUFFIXES snap-core
        HINTS ${Snap_ROOT_DIR}
        DOC "The Snap include directory")
message(STATUS "Snap core: " ${Snap_CORE})

find_path(Snap_GLIB_CORE
        NAMES "base.h"
        PATH_SUFFIXES glib-core
        HINTS ${Snap_ROOT_DIR}
        DOC "The Snap GLib include directory")
message(STATUS "Glib core: " ${Snap_GLIB_CORE})

find_library(Snap_LIBRARY
        NAMES libsnap.a
        HINTS ${Snap_ROOT_DIR}/snap-core
        DOC "The Snap library")
message(STATUS "Snap Library: " ${Snap_LIBRARY})

find_package_handle_standard_args(Snap_FOUND DEFAULT_MSG
        Snap_CORE
        Snap_GLIB_CORE
        Snap_LIBRARY)

if (Snap_FOUND)
    set(Snap_LIBRARIES ${Snap_LIBRARY})
    set(Snap_INCLUDE_DIRS ${Snap_CORE} ${Snap_GLIB_CORE})
    set(Snap_DEFINITIONS)
    message(STATUS "Snap Found: " ${Snap_INCLUDE_DIRS})
else()
    message(FATAL_ERROR "Package Snap not found")
endif (Snap_FOUND)

mark_as_advanced(Snap_ROOT_DIR Snap_INCLUDE_DIR Snap_LIBRARY)

在macOS上，Snap安装在/opt/Snap中，这个脚本从CMakeLists.txt用find_package(Snap REQUIRED)调用。在macOS上，这非常有效，但是在Ubuntu上，脚本报告找不到Snap，即使路径Snap_CORE，Snap_GLIB_CORE和Snap_LIBRARY似乎已找到。在Mac上我使用cmake版本3.10.2，在Linux上我已经尝试了2.8和3.9版本，但我仍然有同样的错误。

由于我无法在Linux机器上修改/opt，我在其他地方安装了Snap并修改了第二行的Snap根目录：

set(Snap_ROOT_DIR $ENV{WORKSPACE_ROOT}/elsewhere/Snap)

Linux机器上给出的错误：

-- Snap_ROOT_DIR: /afs/cs.stanford.edu/u/jdeaton/repos/snap
-- Snap core: /afs/cs.stanford.edu/u/jdeaton/repos/snap/snap-core
-- Glib core: /afs/cs.stanford.edu/u/jdeaton/repos/snap/glib-core
-- Snap Library: /afs/cs.stanford.edu/u/jdeaton/repos/snap/snap-core/libsnap.a
-- Found Snap_FOUND: /afs/cs.stanford.edu/u/jdeaton/repos/snap/snap-core
CMake Error at cmake/FindSnap.cmake:43 (message):
  Package Snap not found
Call Stack (most recent call first):
  CMakeLists.txt:6 (find_package)

看起来这应该工作正常，但不知何故它不起作用，只在Linux上失败。

谢谢！

Answer 1

find_package_handle_standard_args的第一个论点应该是Snap而不是Snap_FOUND。

 find_package_handle_standard_args(Snap DEFAULT_MSG
    Snap_CORE
    Snap_GLIB_CORE
    Snap_LIBRARY)