Rework build targets such that: (earlephilhower#1211)

1. Make sure Pico SDK libraries have the correct dependencies on other SDK libraries
2. Pico SDK libraries all have _headers variants to include the headers. This may facilitate building user STATIC libraries without
   pulling in SDK code, though care will still need to be taken w.r.t. values of #defines
3. Make sure the _headers versions also have the correct dependencies

Note: There are a few exceptions to 1. for some non code libraries like pico_standard_link and pico_cxx_options

Author: kilograham

src/CMakeLists.txt

@@ -27,6 +27,29 @@ function(pico_add_subdirectory subdir)
     pico_promote_common_scope_vars()
 endfunction()
 
+# takes dependencies after the target
+function(pico_mirrored_target_link_libraries TARGET SCOPE)
+    if (${ARGC} LESS 3)
+        message(FATAL_ERROR "expected a target, scope and at least one dependency")
+    endif()
+    if (NOT TARGET ${TARGET}_headers)
+        message(FATAL_ERROR "${TARGET} does not have headers")
+    endif()
+    # library should depend on its own header
+    target_link_libraries(${TARGET} ${SCOPE} ${TARGET}_headers)
+    foreach(DEPENDENCY IN LISTS ARGN)
+        if (DEPENDENCY MATCHES ".*_headers")
+            message(FATAL_ERROR "should not use headers with pico_mirrored_target_link_libraries")
+        endif()
+        # note, it would be nice to only add the dependency if it exists, but we do
+        # not necessarily add libraries in reverse dependency order, so we do this
+        # unconditionally, so this function should only be passed dependencies that
+        # have headers, or link will fail with a missing library -lfoo_headers
+        target_link_libraries(${TARGET}_headers ${SCOPE} ${DEPENDENCY}_headers)
+        target_link_libraries(${TARGET} ${SCOPE} ${DEPENDENCY})
+    endforeach()
+endfunction()
+
 # add a link option to wrap the given function name; i.e. -Wl:wrap=FUNCNAME for gcc
 function(pico_wrap_function TARGET FUNCNAME)
     target_link_options(${TARGET} INTERFACE "LINKER:--wrap=${FUNCNAME}")
@@ -42,18 +65,34 @@ function(pico_add_map_output TARGET)
     endif ()
 endfunction()
 
-# create a hardware_NAME_headers target (see pico_pico_simple_hardware_headers_target)
-# create a hardware_NAME target (see pico_pico_simple_hardware_target)
+# create a hardware_NAME_headers target (see pico_simple_hardware_headers_target)
+# create a hardware_NAME target (see pico_simple_hardware_target)
 macro(pico_simple_hardware_target NAME)
     pico_simple_hardware_headers_target(${NAME})
     pico_simple_hardware_impl_target(${NAME})
 endmacro()
 
 # create an INTERFACE library named target, and define LIB_TARGET=1 (upper case) as a compile option
+# and make it dependent on a pre-existing corresponding _headers library
+# optional arg NOFLAG will skip the LIB_TARGET definition
 function(pico_add_impl_library target)
     add_library(${target} INTERFACE)
     string(TOUPPER ${target} TARGET_UPPER)
-    target_compile_definitions(${target} INTERFACE LIB_${TARGET_UPPER}=1)
+    if (${ARGC} GREATER 1)
+        if (NOT "${ARGV1}" STREQUAL "NOFLAG")
+            message(FATAL_ERROR "Unknown parameter ${ARGV1}")
+        endif()
+    else()
+        target_compile_definitions(${target} INTERFACE LIB_${TARGET_UPPER}=1)
+    endif()
+    target_link_libraries(${target} INTERFACE ${target}_headers)
+endfunction()
+
+# create an INTERFACE library named target along with associated header, and define LIB_TARGET=1 (upper case) as a compile option
+# optional arg NOFLAG will skip the LIB_TARGET definition
+function(pico_add_library target)
+    add_library(${target}_headers INTERFACE)
+    pico_add_impl_library(${target} ${ARGN})
 endfunction()
 
 # create an INTERFACE library named hardware_NAME_headers INTERFACE library if it doesn't already exist,
@@ -66,7 +105,7 @@ macro(pico_simple_hardware_headers_target NAME)
         target_include_directories(hardware_${NAME}_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
         target_link_libraries(hardware_${NAME}_headers INTERFACE pico_base_headers)
         if (NOT PICO_NO_HARDWARE)
-            target_link_libraries(hardware_${NAME}_headers INTERFACE hardware_structs hardware_claim)
+            target_link_libraries(hardware_${NAME}_headers INTERFACE hardware_structs hardware_claim_headers)
         endif()
     endif()
 endmacro()
@@ -80,13 +119,17 @@ macro(pico_simple_hardware_headers_only_target NAME)
         #   super interesting except to determine functionality as they are mostly passive accessors, however
         #   they could be useful to determine if the header is available.
         # pico_add_sdk_impl_library(hardware_${NAME})
-        add_library(hardware_${NAME} INTERFACE)
+        add_library(hardware_${NAME}_headers INTERFACE)
 
-        target_include_directories(hardware_${NAME} INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
-        target_link_libraries(hardware_${NAME} INTERFACE pico_base_headers)
+        # a headers only target should still have an explicit _headers library for consistency
+        target_include_directories(hardware_${NAME}_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
+        target_link_libraries(hardware_${NAME}_headers INTERFACE pico_base_headers)
         if (NOT PICO_NO_HARDWARE)
-            target_link_libraries(hardware_${NAME} INTERFACE hardware_structs)
+            target_link_libraries(hardware_${NAME}_headers INTERFACE hardware_structs)
         endif()
+
+        add_library(hardware_${NAME} INTERFACE)
+        target_link_libraries(hardware_${NAME} INTERFACE hardware_${NAME}_headers)
     endif()
 endmacro()
 
@@ -104,7 +147,10 @@ macro(pico_simple_hardware_impl_target NAME)
                 ${CMAKE_CURRENT_LIST_DIR}/${NAME}.c
                 )
 
-        target_link_libraries(hardware_${NAME} INTERFACE hardware_${NAME}_headers pico_platform)
+        pico_mirrored_target_link_libraries(hardware_${NAME} INTERFACE pico_platform)
+        if (NOT PICO_NO_HARDWARE)
+            target_link_libraries(hardware_${NAME} INTERFACE hardware_claim)
+        endif()
     endif()
 endmacro()
 

src/common/pico_base/CMakeLists.txt

@@ -1,5 +1,5 @@
 if (NOT TARGET pico_base_headers)
-    add_library(pico_base_headers INTERFACE)
+    pico_add_library(pico_base NOFLAG)
     target_include_directories(pico_base_headers INTERFACE include ${CMAKE_BINARY_DIR}/generated/pico_base)
 
     # PICO_BUILD_DEFINE: PICO_BOARD, Name of board, type=string, default=CMake PICO_BOARD variable, group=pico_base
@@ -10,4 +10,5 @@ if (NOT TARGET pico_base_headers)
 
     list(APPEND PICO_SDK_POST_LIST_FILES ${CMAKE_CURRENT_LIST_DIR}/generate_config_header.cmake)
     pico_promote_common_scope_vars()
-endif()
+endif()
+

src/common/pico_stdlib/CMakeLists.txt

@@ -1,11 +1,5 @@
 if (NOT TARGET pico_stdlib_headers)
     add_library(pico_stdlib_headers INTERFACE)
     target_include_directories(pico_stdlib_headers INTERFACE include)
-    target_link_libraries(pico_stdlib_headers INTERFACE
-            hardware_gpio
-            hardware_uart
-            hardware_divider
-            pico_time
-            pico_util
-    )
+    # dependencies handled in implementation CMakeLists.txt
 endif()

src/common/pico_sync/CMakeLists.txt

@@ -1,44 +1,46 @@
 if (NOT TARGET pico_sync_headers)
     add_library(pico_sync_headers INTERFACE)
+    target_link_libraries(pico_sync_headers INTERFACE
+            hardware_sync_headers
+            pico_time_headers)
+endif()
+
+if (NOT TARGET pico_sync)
+    pico_add_impl_library(pico_sync)
     target_include_directories(pico_sync_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
-    target_link_libraries(pico_sync_headers INTERFACE hardware_sync pico_time)
+    pico_mirrored_target_link_libraries(pico_sync INTERFACE pico_sync_sem pico_sync_mutex pico_sync_critical_section pico_time hardware_sync)
 endif()
 
+
 if (NOT TARGET pico_sync_core)
-    pico_add_impl_library(pico_sync_core)
+    pico_add_library(pico_sync_core NOFLAG)
     target_sources(pico_sync_core INTERFACE
             ${CMAKE_CURRENT_LIST_DIR}/lock_core.c
     )
-    target_link_libraries(pico_sync_core INTERFACE pico_sync_headers)
 endif()
 
 if (NOT TARGET pico_sync_sem)
-    pico_add_impl_library(pico_sync_sem)
+    pico_add_library(pico_sync_sem)
     target_sources(pico_sync_sem INTERFACE
         ${CMAKE_CURRENT_LIST_DIR}/sem.c
     )
-    target_link_libraries(pico_sync_sem INTERFACE pico_sync_core pico_time)
+    pico_mirrored_target_link_libraries(pico_sync_sem INTERFACE pico_sync_core)
 endif()
 
 if (NOT TARGET pico_sync_mutex)
-    pico_add_impl_library(pico_sync_mutex)
+    pico_add_library(pico_sync_mutex)
     target_sources(pico_sync_mutex INTERFACE
             ${CMAKE_CURRENT_LIST_DIR}/mutex.c
             )
-    target_link_libraries(pico_sync_mutex INTERFACE pico_sync_core pico_time)
+    pico_mirrored_target_link_libraries(pico_sync_mutex INTERFACE pico_sync_core)
 endif()
 
 if (NOT TARGET pico_sync_critical_section)
-    pico_add_impl_library(pico_sync_critical_section)
+    pico_add_library(pico_sync_critical_section)
     target_sources(pico_sync_critical_section INTERFACE
             ${CMAKE_CURRENT_LIST_DIR}/critical_section.c
             )
-    target_link_libraries(pico_sync_critical_section INTERFACE pico_sync_core pico_time)
-endif()
-
-if (NOT TARGET pico_sync)
-    pico_add_impl_library(pico_sync)
-    target_link_libraries(pico_sync INTERFACE pico_sync_sem pico_sync_mutex pico_sync_critical_section pico_sync_core)
+    pico_mirrored_target_link_libraries(pico_sync_critical_section INTERFACE pico_sync_core)
 endif()
 
 

src/common/pico_time/CMakeLists.txt

@@ -1,9 +1,7 @@
 if (NOT TARGET pico_time_headers)
     add_library(pico_time_headers INTERFACE)
-
     target_include_directories(pico_time_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
-
-    target_link_libraries(pico_time_headers INTERFACE hardware_timer)
+    target_link_libraries(pico_time_headers INTERFACE hardware_timer_headers pico_sync_headers pico_util_headers)
 endif()
 
 if (NOT TARGET pico_time)
@@ -12,5 +10,5 @@ if (NOT TARGET pico_time)
     target_sources(pico_time INTERFACE
             ${CMAKE_CURRENT_LIST_DIR}/time.c
             ${CMAKE_CURRENT_LIST_DIR}/timeout_helper.c)
-    target_link_libraries(pico_time INTERFACE pico_time_headers pico_sync pico_util)
+    target_link_libraries(pico_time INTERFACE hardware_timer pico_sync pico_util)
 endif()

src/common/pico_usb_reset_interface/CMakeLists.txt

@@ -1,2 +1,2 @@
-add_library(pico_usb_reset_interface_headers INTERFACE)
+pico_add_library(pico_usb_reset_interface NOFLAG)
 target_include_directories(pico_usb_reset_interface_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)

src/common/pico_util/CMakeLists.txt

@@ -1,7 +1,7 @@
 if (NOT TARGET pico_util_headers)
     add_library(pico_util_headers INTERFACE)
     target_include_directories(pico_util_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
-    target_link_libraries(pico_util_headers INTERFACE pico_base_headers hardware_sync)
+    target_link_libraries(pico_util_headers INTERFACE pico_base_headers hardware_sync_headers)
 endif()
 
 if (NOT TARGET pico_util)
@@ -11,5 +11,5 @@ if (NOT TARGET pico_util)
             ${CMAKE_CURRENT_LIST_DIR}/pheap.c
             ${CMAKE_CURRENT_LIST_DIR}/queue.c
     )
-    target_link_libraries(pico_util INTERFACE pico_util_headers)
+    pico_mirrored_target_link_libraries(pico_util INTERFACE pico_sync)
 endif()

src/host/hardware_sync/CMakeLists.txt

@@ -7,6 +7,6 @@ if (NOT TARGET hardware_sync)
         ${CMAKE_CURRENT_LIST_DIR}/sync_core0_only.c
     )
 
-    target_link_libraries(hardware_sync INTERFACE hardware_sync_headers pico_platform)
+    pico_mirrored_target_link_libraries(hardware_sync INTERFACE pico_platform)
 endif()
 

src/host/hardware_timer/CMakeLists.txt

@@ -1,6 +1,6 @@
 pico_simple_hardware_target(timer)
 
-target_compile_definitions(hardware_timer INTERFACE
+target_compile_definitions(hardware_timer_headers INTERFACE
     PICO_HARDWARE_TIMER_RESOLUTION_US=1000 # to loosen tests a little
 )
 

src/host/pico_divider/CMakeLists.txt

@@ -3,7 +3,7 @@ pico_add_impl_library(pico_divider)
 target_sources(pico_divider INTERFACE
         ${CMAKE_CURRENT_LIST_DIR}/divider.c)
 
-target_link_libraries(pico_divider INTERFACE pico_divider_headers)
+pico_mirrored_target_link_libraries(pico_divider INTERFACE hardware_divider)
 
 macro(pico_set_divider_implementation TARGET IMPL)
 endmacro()