Missing include dir

The examples are missing the include folder for the installed library

What do you mean exactly?

Headers installed, see foo/Bar.hpp for example:

https://github.com/forexample/package-example#install-foo

Ah sorry. When you install a target and then import that target via find_package it does not have its include directory property set because you don't set it in the CMakeLists:

package-example/Foo/CMakeLists.txt

Line 124 in 00335ff

"$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/Source>"

You need to use INSTALL_INTERFACE generator expression to have it set for the installed target. In general: Where you use BUILD_INTERFACE you usually need the INSTALL_INTERFACE for the same.

You can try it: Install it into a random directory, e.g. /tmp/foo, add this to CMAKE_PREFIX_PATH then try to build against this with standard find_package and target_link_libraries where any source references a header from the installation. Or just check the generated target configs: No header path anywhere.

Side note:

package-example/Foo/CMakeLists.txt

Line 121 in 00335ff

# * header can be included by: `#include <BAR_EXPORT.h>`

is wrong: Should be #include <foo/BAR_EXPORT.h>

When you install a target and then import that target via find_package it does not have its include directory property set

It's set here:

package-example/Foo/CMakeLists.txt

Line 184 in 00335ff

INCLUDES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"

is wrong: Should be #include <foo/BAR_EXPORT.h>

Feel free to send pull request with fix, it's just an old comment

Intresting. So may I assume the INSTALL_INTERFACE for includes is superfluous and/or superseded by the INSTALL DESTINATION for the install(TARGETS command?

https://cmake.org/cmake/help/latest/command/install.html

INCLUDES DESTINATION

    This option specifies a list of directories which will be added to the
    INTERFACE_INCLUDE_DIRECTORIES target property of the <targets> when
    exported by the install(EXPORT) command. If a relative path is specified,
    it is treated as relative to the $<INSTALL_PREFIX>.

https://cmake.org/cmake/help/latest/manual/cmake-generator-expressions.7.html#output-related-expressions

$<INSTALL_INTERFACE:...>

    Content of ... when the property is exported using install(EXPORT), and empty otherwise.

https://cmake.org/cmake/help/latest/command/target_include_directories.html

The INTERFACE, PUBLIC and PRIVATE keywords are required to specify the scope of
the following arguments. PRIVATE and PUBLIC items will populate the
INCLUDE_DIRECTORIES property of <target>. PUBLIC and INTERFACE items will
populate the INTERFACE_INCLUDE_DIRECTORIES property of <target>.

I have not much to add :)

Ah I see the difference: INCLUDES DESTINATION will add it to ALL targets which may not be what is wanted. INSTALL_INTERFACE is more fine-grained.