[vcpkg/scripts/pkgconfig] rewrite pkg-config check for libraries (#11550)

* [vcpkg/scripts/pkgconfig] rewrite pkgconfig check for libraries.

* [vcpkg/scripts/pkgconfig] fix more details.

* [vcpkg/scripts/pkgconfig] smaller improvements

* ws change to check functionallity of script for testing.

* [vcpkg/scripts/pkgconfig] update to latest test version

* Revert "ws change to check functionallity of script for testing."

This reverts commit 26269e9e776009230777d9390465715f2ebac465.

* [nettle] bump control for vcpkg_fixup_pkgconfig test

* [gmp] rerun CI to create new *.pc files

* [gmp/nettle] enable port debug

* [vcpkg/script/pkgconfig] fix path conversion regex for CI

* [CI|OSX] install pkg-config on osx

* [gmp/nettle] disable port debug

* [vcpkg/scripts/pkgconfig] update to latest version of x windows pr

* [zlib] add pkgconfig file

* [zstd] add fixup pkgconfig

* [libpng] add pc file installation

* [bzip2] install pc file and leave a TODO for somebody else ;)

* [bzip2] bump control

* [vcpkg/scripts/pkgconfig] skip checks if pkgconfig cannot be found.
- small bugfix in ignore flags regex

* retry zstd and zlib

* [libpng] retry by adding dl and m to system libraries for osx

* [libpng] add missing vcpkg_fixup_pkgconfig()

* [vcpkg/scripts/pkgconfig] unset var if found. 

fixes checks for other configurations which will be always succesful otherwise

* [libpng] bump control

* [libpng] enable port debug to debug osx regression

* ws change to retrigger osx ci and hopeing that it works

* fix typo

* [libpng] remove -lm flag on apple platforms

* ws change to rerun some ports in ci for good measure after the merge with master

* Re-trigger CI test

* [zstd] add pkgconfig

* [zstd] correct debug link

* [vcpkg/script/pkgconfig] - add more search suffixes for static libs
- add additional debug messages for debuging
- fix unsetting of cache variables hiding issues with debug libraries
- fixed pkgconfig fix in the debug case

* [pcre] add pthread dependency to pcre

* [protobuf] fix pkgconfig

* include quotes around the prefix in the case the prefix path was quoted (fixes some regressions)
add option NOT_STATIC_PKGCONFIG to run pkg-config without the --static argument

* [ignition-msgs5] get rid of a dev warning

* [apr] fix apr regression

* [protobuf] fix protobuf regression

* [sdl1] fix regression due to variable expansion of pkg-config. Use similar regex to the library removal for ignored flags.

* [ignition] fix regression

* remove changes of zlib portfile.

* reset changes in osx ci pipeline

* add DISABLE_PARALLEL_CONFIGURE

Co-authored-by: Jack·Boos·Yu <47264268+JackBoosY@users.noreply.github.com>
Co-authored-by: JackBoosY <yuzaiyang@beyondsoft.com>
Co-authored-by: Billy Robert O'Neal <bion@microsoft.com>

2 files changed, 238 insertions, 152 deletions

diff --git a/scripts/cmake/vcpkg_common_definitions.cmake b/scripts/cmake/vcpkg_common_definitions.cmake
index ee6f34849..4ea0a361d 100644
--- a/scripts/cmake/vcpkg_common_definitions.cmake
+++ b/scripts/cmake/vcpkg_common_definitions.cmake
@@ -129,5 +129,5 @@ endif()
 # Windows system libs
 if(VCPKG_TARGET_IS_WINDOWS)
     list(APPEND VCPKG_SYSTEM_LIBRARIES wsock32)
-    list(APPEND VCPKG_SYSTEM_LIBRARIES ws2_32)
+    list(APPEND VCPKG_SYSTEM_LIBRARIES Ws2_32)
 endif()
diff --git a/scripts/cmake/vcpkg_fixup_pkgconfig.cmake b/scripts/cmake/vcpkg_fixup_pkgconfig.cmake
index 6acb51360..6b840afe2 100644
--- a/scripts/cmake/vcpkg_fixup_pkgconfig.cmake
+++ b/scripts/cmake/vcpkg_fixup_pkgconfig.cmake
@@ -8,6 +8,8 @@
 ##     [RELEASE_FILES <PATHS>...]
 ##     [DEBUG_FILES <PATHS>...]
 ##     [SYSTEM_LIBRARIES <NAMES>...]
+##     [IGNORE_FLAGS <FLAGS>]
+##     [SKIP_CHECK]
 ## )
 ## ```
 ##
@@ -20,10 +22,6 @@
 ## Specifies a list of files to apply the fixes for debug paths.
 ## Defaults to every *.pc file in the folder ${CURRENT_PACKAGES_DIR}/debug/
 ##
-## ### SYSTEM_PACKAGES
-## If the *.pc file contains system packages outside vcpkg these need to be listed here.
-## Since vcpkg checks the existence of all required packages within vcpkg.
-##
 ## ### SYSTEM_LIBRARIES
 ## If the *.pc file contains system libraries outside vcpkg these need to be listed here.
 ## VCPKG checks every -l flag for the existence of the required library within vcpkg.
@@ -31,172 +29,237 @@
 ## ### IGNORE_FLAGS
 ## If the *.pc file contains flags in the lib field which are not libraries. These can be listed here
 ##
+## ### SKIP_CHECK
+## Skips the library checks in vcpkg_fixup_pkgconfig. Only use if the script itself has unhandled cases. 
+##
 ## ## Notes
 ## Still work in progress. If there are more cases which can be handled here feel free to add them
 ##
 ## ## Examples
-##
 ## Just call vcpkg_fixup_pkgconfig() after any install step which installs *.pc files.
-function(vcpkg_fixup_pkgconfig_check_libraries _config _contents_var _system_libs _system_packages _ignore_flags)
-    set(CMAKE_FIND_LIBRARY_SUFFIXES_BACKUP ${CMAKE_FIND_LIBRARY_SUFFIXES})
-    list(APPEND CMAKE_FIND_LIBRARY_SUFFIXES ".lib;.dll.a;.a")
-    #message(STATUS "Checking configuration: ${_config}")
+function(vcpkg_fixup_pkgconfig_check_files pkg_cfg_cmd _file _config _system_libs _ignore_flags)
+    # Setup pkg-config paths
+    if(CMAKE_HOST_WIN32)
+        # Those replacements are probably only necessary since we use pkg-config from msys
+        string(REPLACE " " "\ " _VCPKG_INSTALLED_PKGCONF "${CURRENT_INSTALLED_DIR}")
+        string(REGEX REPLACE "([a-zA-Z]):/" "/\\1/" _VCPKG_INSTALLED_PKGCONF "${_VCPKG_INSTALLED_PKGCONF}")
+        string(REPLACE "\\" "/" _VCPKG_INSTALLED_PKGCONF "${_VCPKG_INSTALLED_PKGCONF}")
+        string(REPLACE " " "\ " _VCPKG_PACKAGES_PKGCONF "${CURRENT_PACKAGES_DIR}")
+        string(REGEX REPLACE "([a-zA-Z]):/" "/\\1/" _VCPKG_PACKAGES_PKGCONF "${_VCPKG_PACKAGES_PKGCONF}")
+        string(REPLACE "\\" "/" _VCPKG_PACKAGES_PKGCONF "${_VCPKG_PACKAGES_PKGCONF}")
+    else()
+        set(_VCPKG_INSTALLED_PKGCONF "${CURRENT_INSTALLED_DIR}")
+        set(_VCPKG_PACKAGES_PKGCONF "${CURRENT_PACKAGES_DIR}")
+    endif()
+    
+    set(PATH_SUFFIX_DEBUG /debug)
+    set(PKGCONFIG_INSTALLED_DIR "${_VCPKG_INSTALLED_PKGCONF}${PATH_SUFFIX_${_config}}/lib/pkgconfig")
+    set(PKGCONFIG_INSTALLED_SHARE_DIR "${_VCPKG_INSTALLED_PKGCONF}/share/pkgconfig")
+    set(PKGCONFIG_PACKAGES_DIR "${_VCPKG_PACKAGES_PKGCONF}${PATH_SUFFIX_${_config}}/lib/pkgconfig")
+    set(PKGCONFIG_PACKAGES_SHARE_DIR "${_VCPKG_PACKAGES_PKGCONF}/share/pkgconfig")
+
+    if(ENV{PKG_CONFIG_PATH})
+        set(BACKUP_ENV_PKG_CONFIG_PATH_${_config} $ENV{PKG_CONFIG_PATH})
+        set(ENV{PKG_CONFIG_PATH} "${PKGCONFIG_INSTALLED_DIR}:${PKGCONFIG_INSTALLED_SHARE_DIR}:${PKGCONFIG_PACKAGES_DIR}:${PKGCONFIG_PACKAGES_SHARE_DIR}:$ENV{PKG_CONFIG_PATH}")
+    else()
+        set(ENV{PKG_CONFIG_PATH} "${PKGCONFIG_INSTALLED_DIR}:${PKGCONFIG_INSTALLED_SHARE_DIR}:${PKGCONFIG_PACKAGES_DIR}:${PKGCONFIG_PACKAGES_SHARE_DIR}")
+    endif()
+
+    # First make sure everything is ok with the package and its deps
+    get_filename_component(_package_name "${_file}" NAME_WLE)
+    debug_message("Checking package (${_config}): ${_package_name}")
+    execute_process(COMMAND "${pkg_cfg_cmd}" --print-errors --exists ${_package_name}
+                    WORKING_DIRECTORY "${CURRENT_BUILDTREES_DIR}"
+                    RESULT_VARIABLE _pkg_error_var
+                    OUTPUT_VARIABLE _pkg_output
+                    ERROR_VARIABLE  _pkg_error_out
+                    OUTPUT_STRIP_TRAILING_WHITESPACE
+                    ERROR_STRIP_TRAILING_WHITESPACE
+                    )
+    if(NOT _pkg_error_var EQUAL 0)
+        message(STATUS "pkg_cfg_cmd call with:${pkg_cfg_cmd} --exists ${_package_name} failed")
+        message(STATUS "ENV{PKG_CONFIG_PATH}:$ENV{PKG_CONFIG_PATH}")
+        message(STATUS "pkg-config call failed with error code:${_pkg_error_var}")
+        message(STATUS "pkg-config output:${_pkg_output}")
+        message(FATAL_ERROR "pkg-config error output:${_pkg_error_out}")
+    else()
+        debug_message("pkg-config returned:${_pkg_error_var}")
+        debug_message("pkg-config output:${_pkg_output}")
+        debug_message("pkg-config error output:${_pkg_error_out}")
+    endif()
+
+    # Get all required libs. --static means we get all libraries required for static linkage 
+    # which is the worst case and includes the case without --static
+    # This retests already tested *.pc files since pkg-config will recursivly search for
+    # required packages and add there link flags to the one being tested
+    # as such NOT_STATIC_PKGCONFIG might be used to deactivate the --static arg to pkg-config
+
+    execute_process(COMMAND "${pkg_cfg_cmd}" --print-errors ${PKGCONFIG_STATIC} --libs ${_package_name}
+                    WORKING_DIRECTORY "${CURRENT_BUILDTREES_DIR}"
+                    RESULT_VARIABLE _pkg_error_var
+                    OUTPUT_VARIABLE _pkg_libs_output
+                    ERROR_VARIABLE  _pkg_error_out
+                    OUTPUT_STRIP_TRAILING_WHITESPACE
+                    ERROR_STRIP_TRAILING_WHITESPACE
+                    )
+    if(NOT _pkg_error_var EQUAL 0)
+        message(STATUS "pkg_cfg_cmd call with:${pkg_cfg_cmd} --libs ${_package_name} failed")
+        message(STATUS "pkg-config call failed with error code:${_pkg_error_var}")
+        message(STATUS "pkg-config output:${_pkg_libs_output}")
+        message(FATAL_ERROR "pkg-config error output:${_pkg_error_out}")
+    else()
+        debug_message("pkg-config returned:${_pkg_error_var}")
+        debug_message("pkg-config output:${_pkg_libs_output}")
+        debug_message("pkg-config error output:${_pkg_error_out}")
+    endif()
+
+    execute_process(COMMAND "${pkg_cfg_cmd}" --print-errors --static --libs-only-L ${_package_name}
+                    WORKING_DIRECTORY "${CURRENT_BUILDTREES_DIR}"
+                    RESULT_VARIABLE _pkg_error_var
+                    OUTPUT_VARIABLE _pkg_lib_paths_output
+                    ERROR_VARIABLE  _pkg_error_out
+                    OUTPUT_STRIP_TRAILING_WHITESPACE
+                    ERROR_STRIP_TRAILING_WHITESPACE
+                    )
+
+    if(NOT _pkg_error_var EQUAL 0)
+        message(STATUS "pkg_cfg_cmd call with:${pkg_cfg_cmd} --libs-only-L ${_package_name} failed")
+        message(STATUS "pkg-config call failed with error code:${_pkg_error_var}")
+        message(STATUS "pkg-config output:${_pkg_lib_paths_output}")
+        message(FATAL_ERROR "pkg-config error output:${_pkg_error_out}")
+    else()
+        debug_message("pkg-config returned:${_pkg_error_var}")
+        debug_message("pkg-config output:${_pkg_lib_paths_output}")
+        debug_message("pkg-config error output:${_pkg_error_out}")
+    endif()
+
+    string(REPLACE "\\ " "##" _pkg_lib_paths_output "${_pkg_lib_paths_output}") # Whitespace path protection
+    string(REGEX REPLACE "(^[\t ]*|[\t ]+)-L" ";" _pkg_lib_paths_output "${_pkg_lib_paths_output}")
+    debug_message("-L LIST TRANSFORMATION:'${_pkg_lib_paths_output}'")
+    string(REGEX REPLACE "^[\t ]*;" "" _pkg_lib_paths_output "${_pkg_lib_paths_output}")
+    string(REPLACE "##" "\\ " _pkg_lib_paths_output "${_pkg_lib_paths_output}")
+
+    list(REMOVE_DUPLICATES _pkg_lib_paths_output) # We don't care about linker order and repeats
+    ## Remove search paths from LIBS
+    foreach(_search_path IN LISTS _pkg_lib_paths_output)
+        debug_message("REMOVING:'${_search_path}'")
+        debug_message("FROM:'${_pkg_libs_output}'")
+        string(REGEX REPLACE "(^[\t ]*|[\t ]+|;[\t ]*)-L${_search_path}([\t ]+|[\t ]*$)" ";" _pkg_libs_output "${_pkg_libs_output}") # Remove search paths from libs
+    endforeach()
+    debug_message("LIBS AFTER -L<path> REMOVAL:'${_pkg_libs_output}'")
+
+    #Make the remaining libs a proper CMake List
+    string(REPLACE "\\ " "##" _pkg_libs_output "${_pkg_libs_output}") # Whitespace path protection
+    string(REGEX REPLACE "(^[\t ]*|[\t ]+)-l" ";-l" _pkg_libs_output "${_pkg_libs_output}")
+    string(REGEX REPLACE "[\t ]*(-pthreads?)" ";\\1" _pkg_libs_output "${_pkg_libs_output}") # handle pthread without -l here (makes a lot of problems otherwise)
+    string(REGEX REPLACE "^[\t ]*;[\t ]*" "" _pkg_libs_output "${_pkg_libs_output}")
+    string(REPLACE "##" "\\ " _pkg_libs_output "${_pkg_libs_output}")
+
+    #Windows path transformations
+    if(CMAKE_HOST_WIN32)
+        string(REGEX REPLACE "(^|;)/([a-zA-Z])/" "\\1\\2:/" _pkg_lib_paths_output "${_pkg_lib_paths_output}")
+        string(REGEX REPLACE " /([a-zA-Z])/" ";\\1:/" _pkg_libs_output "${_pkg_libs_output}")
+        string(REGEX REPLACE "-l/([a-zA-Z])/" "-l\\1:/" _pkg_libs_output "${_pkg_libs_output}")
+        debug_message("pkg-config output lib paths after replacement (cmake style):${_pkg_lib_paths_output}")
+        debug_message("pkg-config output lib after replacement (cmake style):${_pkg_libs_output}")
+    endif()
+
     if("${_config}" STREQUAL "DEBUG")
-        set(prefix "${CURRENT_INSTALLED_DIR}/debug/")
-        set(libprefix "${CURRENT_INSTALLED_DIR}/debug/lib/")
-        set(installprefix "${CURRENT_PACKAGES_DIR}/debug/")
-        set(installlibprefix "${CURRENT_PACKAGES_DIR}/debug/lib/")
-        set(lib_suffixes d _d _debug)
+        set(lib_suffixes d _d _debug -s -sd _s _sd -static -staticd _static _staticd)
     elseif("${_config}" STREQUAL "RELEASE")
-        set(prefix "${CURRENT_INSTALLED_DIR}")
-        set(libprefix "${CURRENT_INSTALLED_DIR}/lib/")
-        set(installprefix "${CURRENT_PACKAGES_DIR}/")
-        set(installlibprefix "${CURRENT_PACKAGES_DIR}/lib/")
-        set(lib_suffixes "")
+        set(lib_suffixes -s _s -static _static)
     else()
         message(FATAL_ERROR "Unknown configuration in vcpkg_fixup_pkgconfig_check_libraries!")
     endif()
-    debug_message("Default library search paths: ${libprefix} --- ${installlibprefix} --- ${PKG_LIB_SEARCH_PATH}")
-    set(_contents "${${_contents_var}}")
-    #message(STATUS "Contents: ${_contents}")
-    set(_system_lib_normalized)
-    foreach(_system_lib ${_system_libs})
-        string(REPLACE "-l" "" _system_lib "${_system_lib}")
-        list(APPEND _system_lib_normalized "${_system_lib}")
+
+    debug_message("IGNORED FLAGS:'${_ignore_flags}'")
+    debug_message("BEFORE IGNORE FLAGS REMOVAL: ${_pkg_libs_output}")
+    foreach(_ignore IN LISTS _ignore_flags)  # Remove ignore with whitespace
+        debug_message("REMOVING FLAG:'${_ignore}'")
+        string(REGEX REPLACE "(^[\t ]*|;[\t ]*|[\t ]+)${_ignore}([\t ]+|[\t ]*;|[\t ]*$)" "\\2" _pkg_libs_output "${_pkg_libs_output}")
+        debug_message("AFTER REMOVAL: ${_pkg_libs_output}")
     endforeach()
 
-    ## Extra libraries:
-    string(REGEX MATCH "Libs:[^\n#]+" _libs "${_contents}")
-    #message(STATUS "LIB LINE: ${_libs}")
-    # The path to the library is either quoted and can not contain a quote or it is unqouted and cannot contain a single unescaped space
-    string(REGEX REPLACE "Libs:" "" _libs_list_tmp "${_libs}")
-    string(REGEX REPLACE [[[\t ]+(-(l|L)?("[^"]+"|(\\ |[^ ]+)+))]] ";\\1" _libs_list_tmp "${_libs_list_tmp}")
+    string(REGEX REPLACE ";?[\t ]*;[\t ]*" ";" _pkg_libs_output "${_pkg_libs_output}") # Double ;; and Whitespace before/after ; removal
 
-    string(REGEX MATCH "Libs.private:[^\n#]+" _libs_private "${_contents}")
-    string(REGEX REPLACE "Libs.private:" "" _libs_private_list_tmp "${_libs_private}")
-    string(REGEX REPLACE [[[\t ]+(-(l|L)?("[^"]+"|(\\ |[^ ]+)+))]] ";\\1" _libs_private_list_tmp "${_libs_private_list_tmp}")
+    debug_message("SYSTEM LIBRARIES:'${_system_libs}'")
+    debug_message("LIBRARIES in PC:'${_pkg_libs_output}'")
+    foreach(_system_lib IN LISTS _system_libs)  # Remove system libs with whitespace
+        debug_message("REMOVING:'${_system_lib}'")
+        debug_message("FROM:'${_pkg_libs_output}'")
+        string(REGEX REPLACE "(^[\t ]*|;[\t ]*|[\t ]+)(-l?)${_system_lib}([\t ]+|[\t ]*;|[\t ]*$)" "\\3" _pkg_libs_output "${_pkg_libs_output}")
+        string(REGEX REPLACE "(^[\t ]*|;[\t ]*|[\t ]+)${_system_lib}([\t ]+|[\t ]*;|[\t ]*$)" "\\2" _pkg_libs_output "${_pkg_libs_output}")
+        string(TOLOWER "${_system_lib}" _system_lib_lower)
+        string(REGEX REPLACE "(^[\t ]*|;[\t ]*|[\t ]+)(-l?)${_system_lib_lower}([\t ]+|[\t ]*;|[\t ]*$)" "\\3" _pkg_libs_output "${_pkg_libs_output}")
+        string(REGEX REPLACE "(^[\t ]*|;[\t ]*|[\t ]+)${_system_lib_lower}([\t ]+|[\t ]*;|[\t ]*$)" "\\2" _pkg_libs_output "${_pkg_libs_output}")
+        debug_message("AFTER REMOVAL:'${_pkg_libs_output}'")
+    endforeach()
+    list(REMOVE_DUPLICATES _pkg_libs_output) # We don't care about linker order and repeats
 
-    #message(STATUS "Found libraries: ${_libs_list_tmp}")
-    #message(STATUS "Found private libraries: ${_libs_private_list_tmp}")
-    list(APPEND _all_libs "${_libs_list_tmp}" "${_libs_private_list_tmp}")
-    list(REMOVE_DUPLICATES _all_libs)
-    foreach(_lib ${_all_libs})
-        string(REGEX REPLACE "(^[\t ]+|[\t ]+$)" "" _lib "${_lib}") # Remove whitespaces at begin & end
-        if( "x${_lib}x" STREQUAL "xx") #Empty String
-            continue()
-        endif()
-        unset(CHECK_LIB CACHE)
-        unset(NO_CHECK_LIB)
-        #message(STATUS "CHECKING: x${_lib}z")
-        if("${_lib}" MATCHES "^-L((\\ |[^ ]+)+)$")
-            debug_message("Search path for libraries (unused): ${CMAKE_MATCH_1}") # not used yet we assume everything can be found in libprefix
+    string(REGEX REPLACE ";?[\t ]*;[\t ]*" ";" _pkg_libs_output "${_pkg_libs_output}") # Double ;; and Whitespace before/after ; removal
+
+    debug_message("Library search paths:${_pkg_lib_paths_output}")
+    debug_message("Libraries to search:${_pkg_libs_output}")
+    set(CMAKE_FIND_LIBRARY_SUFFIXES_BACKUP ${CMAKE_FIND_LIBRARY_SUFFIXES})
+    list(APPEND CMAKE_FIND_LIBRARY_SUFFIXES .lib .dll.a .a)
+    foreach(_lib IN LISTS _pkg_libs_output)
+        if(EXISTS "${_lib}" OR "x${_lib}x" STREQUAL "xx" ) # eat; all ok _lib is a fullpath to a library or empty
             continue()
-        elseif("${_lib}" MATCHES [[^-l("[^"]+"|(\\ |[^ ]+)+)$]] )
-            set(_libname ${CMAKE_MATCH_1})
-            debug_message("Searching for library: ${_libname}")
-            #debug_message("System libraries: ${_system_libs}")
-            foreach(_system_lib ${_system_libs})
-                string(REPLACE "^[\t ]*-l" "" _libname_norm "${_libname}")
-                string(REGEX REPLACE "[\t ]+$" "" _libname_norm "${_libname_norm}")
-                #debug_message("${_libname_norm} vs ${_system_lib}")
-                if("${_libname_norm}" MATCHES "${_system_lib}" OR "-l${_libname_norm}" MATCHES "${_system_lib}")
-                    set(NO_CHECK_LIB ON)
-                    debug_message("${_libname} is SYSTEM_LIBRARY")
-                    break()
-                endif()
-            endforeach()
-            if(NO_CHECK_LIB)
-                break()
+        elseif (_lib MATCHES "^-l(.+)$")
+            debug_message("Library match: CMAKE_MATCH_1:${CMAKE_MATCH_1}")
+            set(_libname "${CMAKE_MATCH_1}")
+            if(EXISTS "${_libname}")
+                debug_message("${_libname} detected as an existing full path!")
+                continue() # fullpath in -l argument and exists; all ok
             endif()
-            #debug_message("Searching for library ${_libname} in ${libprefix}")
-            if(EXISTS "${_libname}") #full path
-                set(CHECK_LIB_${_libname} "${_libname}" CACHE INTERNAL FORCE)
+            debug_message("CHECK_LIB_${_libname}_${_config} before: ${CHECK_LIB_${_libname}_${_config}}")
+            find_library(CHECK_LIB_${_libname}_${_config} NAMES ${_libname} PATHS ${_pkg_lib_paths_output} "${CURRENT_INSTALLED_DIR}${PATH_SUFFIX_${_config}}/lib" NO_DEFAULT_PATH)
+            debug_message("CHECK_LIB_${_libname}_${_config} after: ${CHECK_LIB_${_libname}_${_config}}")
+            if(CHECK_LIB_${_libname}_${_config})
+                unset(CHECK_LIB_${_libname}_${_config} CACHE) # need to unset or else other configurations will not check correctly
+                debug_message("CHECK_LIB_${_libname}_${_config} after unset: ${CHECK_LIB_${_libname}_${_config}}")
+                continue() # found library; all ok
             endif()
-            find_library(CHECK_LIB_${_libname} NAMES "${_libname}" PATHS "${libprefix}" "${installlibprefix}" "${PKG_LIB_SEARCH_PATH}" NO_DEFAULT_PATH)
-            if(NOT CHECK_LIB_${_libname} AND "${_config}" STREQUAL "DEBUG")
-                #message(STATUS "Unable to locate ${_libname}. Trying with debug suffix")
-                foreach(_lib_suffix ${lib_suffixes})
-                    string(REPLACE ".dll.a|.a|.lib|.so" "" _name_without_extension "${_libname}")
-                    find_library(CHECK_LIB_${_libname} NAMES ${_name_without_extension}${_lib_suffix} PATHS "${libprefix}" "${installlibprefix}" "${PKG_LIB_SEARCH_PATH}")
-                    if(CHECK_LIB_${_libname})
-                        message(FATAL_ERROR "Found ${CHECK_LIB_${_libname}} with additional debug suffix! Please correct the *.pc file!")
-                        string(REGEX REPLACE "(-l${_name_without_extension})(\.dll\.a|\.a|\.lib|\.so)" "\\1${_lib_suffix}\\2" _contents ${_contents})
-                    endif()
-                endforeach()
-                if(NOT CHECK_LIB_${_libname})
-                    message(FATAL_ERROR "Library ${_libname} was not found! If it is a system library use the SYSTEM_LIBRARIES parameter for the vcpkg_fixup_pkgconfig call! Otherwise, corret the *.pc file")
+            debug_message("Searching with additional suffixes: '${lib_suffixes}'")
+            foreach(_lib_suffix IN LISTS lib_suffixes)
+                string(REPLACE ".dll.a|.a|.lib|.so" "" _name_without_extension "${_libname}")
+                set(search_name ${_name_without_extension}${_lib_suffix})
+                debug_message("Search name: '${search_name}'")
+                debug_message("CHECK_LIB_${search_name}_${_config} before: ${CHECK_LIB_${search_name}_${_config}}")
+                debug_message("Search paths:'${_pkg_lib_paths_output}' '${CURRENT_INSTALLED_DIR}${PATH_SUFFIX_${_config}}/lib'")
+                find_library(CHECK_LIB_${search_name}_${_config} NAMES ${search_name} PATHS ${_pkg_lib_paths_output} "${CURRENT_INSTALLED_DIR}${PATH_SUFFIX_${_config}}/lib" NO_DEFAULT_PATH)
+                debug_message("CHECK_LIB_${search_name}_${_config} after: ${CHECK_LIB_${search_name}_${_config}}")
+                if(CHECK_LIB_${search_name}_${_config})
+                    message(FATAL_ERROR "Found ${CHECK_LIB_${search_name}_${_config}} with additional '${_lib_suffix}' suffix! Please correct the *.pc file!")
+                    unset(CHECK_LIB_${search_name}_${_config} CACHE) # need to unset or else other configurations will not check correctly
                 endif()
-            elseif(NOT CHECK_LIB_${_libname})
-                message(FATAL_ERROR "Library ${_libname} was not found! If it is a system library use the SYSTEM_LIBRARIES parameter for the vcpkg_fixup_pkgconfig call! Otherwise, corret the *.pc file")
-            else()
-                debug_message("Found ${_libname} at ${CHECK_LIB_${_libname}}")
-            endif()
-        else()
-            #handle special cases
-            if(_lib STREQUAL "-pthread" OR _lib STREQUAL "-pthreads")
-                # Replace with VCPKG version?
-                #VCPKG should probably rename one of the pthread versions to avoid linking against system pthread?
-                # set(PTHREAD_SUFFIX )
-                # if("${_config}" STREQUAL "DEBUG")
-                    # file(GLOB PTHREAD_LIB "${CURRENT_INSTALLED_DIR}/debug/lib/${VCPKG_TARGET_STATIC_LIBRARY_PREFIX}pthread*C3d.*")
-                # elseif("${_config}" STREQUAL "RELEASE")
-                    # file(GLOB PTHREAD_LIB "${CURRENT_INSTALLED_DIR}/lib/${VCPKG_TARGET_STATIC_LIBRARY_PREFIX}pthread*C3.*")
-                # endif()
-                # get_filename_component(PTHREAD_LIB "${PTHREAD_LIB}" NAME_WE)
-                # string(REPLACE "Libs: -pthread" "Libs: -L\${libdir} -l${PTHREAD_LIB}" _contents ${_contents})
-            elseif(_lib STREQUAL _ignore_flags)
-                message(STATUS "${_lib} found in *.pc file and ignored!")
-            else()
-                message(FATAL_ERROR "Found ${_lib} and no rule to analyse the flag! Please check the *.pc file")
-            endif()
+            endforeach()
+            # Reaching here means error!
+            message(STATUS "CHECK_LIB_${_libname}_${_config}:${CHECK_LIB_${_libname}_${_config}}")
+            message(FATAL_ERROR "Library \"${_libname}\" was not found! If it is a system library use the SYSTEM_LIBRARIES parameter for the vcpkg_fixup_pkgconfig call! Otherwise, correct the *.pc file")
+        else ()
+            message(FATAL_ERROR "Unhandled string \"${_lib}\" was found! If it is a system library use the SYSTEM_LIBRARIES parameter for the vcpkg_fixup_pkgconfig call! Otherwise, correct the *.pc file or add the case to vcpkg_fixup_pkgconfig")
         endif()
-        unset(CHECK_LIB_${_libname} CACHE)
-        unset(NO_CHECK_LIB)
     endforeach()
 
-    ## Packages:
-    string(REGEX MATCH "Requires:[^\n#]+" _pkg_list_tmp "${_contents}")
-    string(REGEX REPLACE "Requires:[\t ]" "" _pkg_list_tmp "${_pkg_list_tmp}")
-    string(REGEX REPLACE "[\t ]*,[\t ]*" ";" _pkg_list_tmp "${_pkg_list_tmp}")
-    string(REGEX REPLACE "[\t ]*(>|=)+[\t ]*([0-9]+|\\.)+" "" _pkg_list_tmp "${_pkg_list_tmp}")
-    string(REGEX REPLACE " " ";" _pkg_list_tmp "${_pkg_list_tmp}")
-    string(REGEX MATCH "Requires.private:[^\n#]+" _pkg_private_list_tmp "${_contents}")
-    string(REGEX REPLACE "Requires.private:[\t ]" "" _pkg_private_list_tmp "${_pkg_private_list_tmp}")
-    string(REGEX REPLACE "[\t ]*,[\t ]*" ";" _pkg_private_list_tmp "${_pkg_private_list_tmp}")
-    string(REGEX REPLACE "[\t ]*(>|=)+[\t ]*([0-9]+|\\.)+" " " _pkg_private_list_tmp "${_pkg_private_list_tmp}")
-    string(REGEX REPLACE "[\t ]+" ";" _pkg_private_list_tmp "${_pkg_private_list_tmp}")
-
-    debug_message("Required packages: ${_pkg_list_tmp}")
-    debug_message("Required private packages: ${_pkg_private_list_tmp}")
-
-    #message(STATUS "System packages: ${_system_packages}")
-    foreach(_package  ${_pkg_list_tmp} ${_pkg_private_list_tmp})
-        debug_message("Searching for package: ${_package}")
-        set(PKG_CHECK ON)
-        if(NOT "${_system_packages}" STREQUAL "")
-            #message(STATUS "Checking ${_package} for SYSTEM PACKAGE: ${_system_packages}")
-            if("${_system_packages}" MATCHES "${_package}" )
-                debug_message("Package ${_package} is SYSTEM PACKAGE!")
-                set(PKG_CHECK OFF)
-            endif()
-        endif()
-        if(PKG_CHECK AND NOT (EXISTS "${libprefix}/pkgconfig/${_package}.pc" OR EXISTS "${installlibprefix}/pkgconfig/${_package}.pc" OR EXISTS "${PKG_LIB_SEARCH_PATH}/pkgconfig/${_package}.pc"))
-            message(FATAL_ERROR "Package ${_package} not found! If it is a system package add it to the SYSTEM_PACKAGES parameter for the vcpkg_fixup_pkgconfig call! Otherwise, corret the *.pc file")
-        else()
-            debug_message("Found package ${_package}!")
-        endif()
-    endforeach()
-    ## Push modifications up in scope
-    set(${_contents_var} "${_contents}" PARENT_SCOPE)
     set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES_BACKUP})
 endfunction()
 
 function(vcpkg_fixup_pkgconfig)
-    cmake_parse_arguments(_vfpkg "" "" "RELEASE_FILES;DEBUG_FILES;SYSTEM_LIBRARIES;SYSTEM_PACKAGES;IGNORE_FLAGS" ${ARGN})
+    cmake_parse_arguments(_vfpkg "SKIP_CHECK;NOT_STATIC_PKGCONFIG" "" "RELEASE_FILES;DEBUG_FILES;SYSTEM_LIBRARIES;SYSTEM_PACKAGES;IGNORE_FLAGS" ${ARGN})
 
+    # Note about SYSTEM_PACKAGES: pkg-config requires all packages mentioned in pc files to exists. Otherwise pkg-config will fail to find the pkg.
+    # As such naming any SYSTEM_PACKAGES is damned to fail which is why it is not mentioned in the docs at the beginning.
     if(VCPKG_SYSTEM_LIBRARIES)
         list(APPEND _vfpkg_SYSTEM_LIBRARIES ${VCPKG_SYSTEM_LIBRARIES})
     endif()
+
+    if(_vfpkg_NOT_STATIC_PKGCONFIG)
+        set(PKGCONFIG_STATIC)
+    else()
+        set(PKGCONFIG_STATIC --static)
+    endif()
+    
     message(STATUS "Fixing pkgconfig")
     if(_vfpkg_UNPARSED_ARGUMENTS)
         message(FATAL_ERROR "vcpkg_fixup_pkgconfig was passed extra arguments: ${_vfct_UNPARSED_ARGUMENTS}")
@@ -212,7 +275,20 @@ function(vcpkg_fixup_pkgconfig)
         list(FILTER _vfpkg_DEBUG_FILES INCLUDE REGEX "${CURRENT_PACKAGES_DIR}/debug/")
     endif()
 
-    #Absolute Unix like paths
+    if(NOT PKGCONFIG)
+        find_program(PKGCONFIG pkg-config PATHS "bin" "/usr/bin" "/usr/local/Cellar/pkg-config/0.29.2_3" REQUIRED)
+        if(NOT PKGCONFIG AND CMAKE_HOST_WIN32)
+            vcpkg_acquire_msys(MSYS_ROOT PACKAGES pkg-config)
+            find_program(PKGCONFIG pkg-config PATHS "${MSYS_ROOT}/usr/bin" REQUIRED)
+        endif()
+        debug_message("Using pkg-config from: ${PKGCONFIG}")
+        if(NOT PKGCONFIG AND NOT _vfpkg_SKIP_CHECK)
+            message(WARNING "Unable to find pkg-config to validate *.pc files. Skipping checkes!")
+            set(_vfpkg_SKIP_CHECK TRUE)
+        endif()
+    endif()
+
+    #Absolute Unix like paths 
     string(REGEX REPLACE "([a-zA-Z]):/" "/\\1/" _VCPKG_PACKAGES_DIR "${CURRENT_PACKAGES_DIR}")
     string(REGEX REPLACE "([a-zA-Z]):/" "/\\1/" _VCPKG_INSTALLED_DIR "${CURRENT_INSTALLED_DIR}")
 
@@ -223,19 +299,24 @@ function(vcpkg_fixup_pkgconfig)
         get_filename_component(PKG_LIB_SEARCH_PATH "${_file}" DIRECTORY)
         file(RELATIVE_PATH RELATIVE_PC_PATH "${PKG_LIB_SEARCH_PATH}" "${CURRENT_PACKAGES_DIR}")
         string(REGEX REPLACE "/$" "" RELATIVE_PC_PATH "${RELATIVE_PC_PATH}")
-        string(REGEX REPLACE "/pkgconfig/?" "" PKG_LIB_SEARCH_PATH "${PKG_LIB_SEARCH_PATH}")
+        #Correct *.pc file
         file(READ "${_file}" _contents)
         string(REPLACE "${CURRENT_PACKAGES_DIR}" "\${prefix}" _contents "${_contents}")
         string(REPLACE "${CURRENT_INSTALLED_DIR}" "\${prefix}" _contents "${_contents}")
         string(REPLACE "${_VCPKG_PACKAGES_DIR}" "\${prefix}" _contents "${_contents}")
         string(REPLACE "${_VCPKG_INSTALLED_DIR}" "\${prefix}" _contents "${_contents}")
-
-        string(REGEX REPLACE "^prefix=(\\\\)?\\\${prefix}" "prefix=\${pcfiledir}/${RELATIVE_PC_PATH}" _contents "${_contents}") # make pc file relocatable
-        vcpkg_fixup_pkgconfig_check_libraries("RELEASE" _contents "${_vfpkg_SYSTEM_LIBRARIES}" "${_vfpkg_SYSTEM_PACKAGES}" "${_vfpkg_IGNORE_FLAGS}")
+        string(REGEX REPLACE "^prefix=(\")?(\\\\)?\\\${prefix}(\")?" "prefix=\${pcfiledir}/${RELATIVE_PC_PATH}" _contents "${_contents}") # make pc file relocatable
+        string(REGEX REPLACE "[\n]prefix=(\")?(\\\\)?\\\${prefix}(\")?" "\nprefix=\${pcfiledir}/${RELATIVE_PC_PATH}" _contents "${_contents}") # make pc file relocatable
         file(WRITE "${_file}" "${_contents}")
         unset(PKG_LIB_SEARCH_PATH)
     endforeach()
 
+    if(NOT _vfpkg_SKIP_CHECK) # The check can only run after all files have been corrected!
+        foreach(_file ${_vfpkg_RELEASE_FILES})
+            vcpkg_fixup_pkgconfig_check_files("${PKGCONFIG}" "${_file}" "RELEASE" "${_vfpkg_SYSTEM_LIBRARIES}" "${_vfpkg_IGNORE_FLAGS}")
+        endforeach()
+    endif()
+
     message(STATUS "Fixing pkgconfig - debug")
     debug_message("Files: ${_vfpkg_DEBUG_FILES}")
     foreach(_file ${_vfpkg_DEBUG_FILES})
@@ -244,24 +325,29 @@ function(vcpkg_fixup_pkgconfig)
         file(RELATIVE_PATH RELATIVE_PC_PATH "${PKG_LIB_SEARCH_PATH}" "${CURRENT_PACKAGES_DIR}/debug/")
         string(REGEX REPLACE "/$" "" RELATIVE_PC_PATH "${RELATIVE_PC_PATH}")
         string(REGEX REPLACE "/pkgconfig/?" "" PKG_LIB_SEARCH_PATH "${PKG_LIB_SEARCH_PATH}")
+        #Correct *.pc file
         file(READ "${_file}" _contents)
         string(REPLACE "${CURRENT_PACKAGES_DIR}" "\${prefix}" _contents "${_contents}")
         string(REPLACE "${CURRENT_INSTALLED_DIR}" "\${prefix}" _contents "${_contents}")
         string(REPLACE "${_VCPKG_PACKAGES_DIR}" "\${prefix}" _contents "${_contents}")
         string(REPLACE "${_VCPKG_INSTALLED_DIR}" "\${prefix}" _contents "${_contents}")
-
         string(REPLACE "debug/include" "../include" _contents "${_contents}")
         string(REPLACE "\${prefix}/include" "\${prefix}/../include" _contents "${_contents}")
         string(REPLACE "debug/share" "../share" _contents "${_contents}")
         string(REPLACE "\${prefix}/share" "\${prefix}/../share" _contents "${_contents}")
         string(REPLACE "debug/lib" "lib" _contents "${_contents}") # the prefix will contain the debug keyword
-
-        string(REGEX REPLACE "^prefix=(\\\\)?\\\${prefix}(/debug)?" "prefix=\${pcfiledir}/${RELATIVE_PC_PATH}" _contents "${_contents}") # make pc file relocatable
-        string(REPLACE "\${prefix}/debug" "\${prefix}" _contents "${_contents}") # replace remaining debug paths if they exist.
-        vcpkg_fixup_pkgconfig_check_libraries("DEBUG" _contents "${_vfpkg_SYSTEM_LIBRARIES}" "${_vfpkg_SYSTEM_PACKAGES}" "${_vfpkg_IGNORE_FLAGS}")
+        string(REGEX REPLACE "^prefix=(\")?(\\\\)?\\\${prefix}(/debug)?(\")?" "prefix=\${pcfiledir}/${RELATIVE_PC_PATH}" _contents "${_contents}") # make pc file relocatable
+        string(REGEX REPLACE "[\n]prefix=(\")?(\\\\)?\\\${prefix}(/debug)?(\")?" "\nprefix=\${pcfiledir}/${RELATIVE_PC_PATH}" _contents "${_contents}") # make pc file relocatable
+        string(REPLACE "\${prefix}/debug" "\${prefix}" _contents "${_contents}") # replace remaining debug paths if they exist. 
         file(WRITE "${_file}" "${_contents}")
         unset(PKG_LIB_SEARCH_PATH)
     endforeach()
+
+    if(NOT _vfpkg_SKIP_CHECK) # The check can only run after all files have been corrected!
+        foreach(_file ${_vfpkg_DEBUG_FILES})
+            vcpkg_fixup_pkgconfig_check_files("${PKGCONFIG}" "${_file}" "DEBUG" "${_vfpkg_SYSTEM_LIBRARIES}" "${_vfpkg_IGNORE_FLAGS}")
+        endforeach()
+    endif()
     message(STATUS "Fixing pkgconfig --- finished")
 
     set(VCPKG_FIXUP_PKGCONFIG_CALLED TRUE CACHE INTERNAL "See below" FORCE)