Question

I noticed a possible mismatch in the installed CMake package export. I may be missing the intended external usage, so I wanted to ask before proposing a patch.

In current master, the target exports this include directory for installed consumers:

target_include_directories(
  ${PROJECT_NAME}
  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/src/>
         $<INSTALL_INTERFACE:include/bacnet/>)

The install rules install the BACnet headers under ${CMAKE_INSTALL_INCLUDEDIR}/bacnet:

install(
  DIRECTORY src/bacnet
  DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
  COMPONENT dev
  FILES_MATCHING
  PATTERN "*.h")

This produces installed headers like:

${prefix}/include/bacnet/bacdef.h
${prefix}/include/bacnet/bacapp.h
${prefix}/include/bacnet/datalink/dlenv.h

Many source files and headers use the bacnet/... include style, for example:

#include "bacnet/bacdef.h"
#include "bacnet/bacapp.h"
#include "bacnet/datalink/dlenv.h"

For that include style, the include root normally needs to be:

${prefix}/include

However, the installed CMake target currently gives consumers:

${prefix}/include/bacnet

That appears to be one level deeper than the installed header layout expects for #include <bacnet/...>.

There is also a related detail: the port headers are installed directly under ${prefix}/include, for example:

${prefix}/include/bacport.h
${prefix}/include/rs485.h
${prefix}/include/dlmstp_port.h

Those headers are not visible through ${prefix}/include/bacnet.

Potential impact

A downstream CMake consumer using the installed package, for example:

find_package(bacnet-stack CONFIG REQUIRED)
target_link_libraries(my_app PRIVATE bacnet-stack::bacnet-stack)

may receive an include path that is one level too deep.

This can make the usual include style fail:

#include <bacnet/bacdef.h>

because the compiler may look for:

${prefix}/include/bacnet/bacnet/bacdef.h

Possible fix

If the intended public include style is #include <bacnet/...>, would changing the installed interface to the following be acceptable?

target_include_directories(
  ${PROJECT_NAME}
  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/src/>
         $<INSTALL_INTERFACE:include>)

This would keep the source-tree build behavior unchanged, while making installed CMake consumers use ${prefix}/include, which matches the installed header layout.

Question for maintainers

Is $<INSTALL_INTERFACE:include/bacnet/> intentional for external CMake consumers, or would a small PR changing it to $<INSTALL_INTERFACE:include> be welcome?

I can prepare a minimal PR if this matches the intended installed package usage.