CMake: Use cmake for xxhash, fix export (litespeedtech#70)

* CMake: Prefer xxHash CMake, fix exported config

* CI: Test both CMake and pkgconfig

Author: dg0yt

.appveyor.yml

@@ -9,8 +9,13 @@ environment:
   matrix:
   - job_name: "Internal xxhash"
     LSQPACK_XXH: ON
-  - job_name: "External xxhash"
+    XXH_CMAKE: UNUSED
+  - job_name: "External xxhash (CMake)"
     LSQPACK_XXH: OFF
+    XXH_CMAKE: REQUIRE
+  - job_name: "External xxhash (pkgconfig)"
+    LSQPACK_XXH: OFF
+    XXH_CMAKE: DISABLE
 
 before_build:
   - git -C c:\tools\vcpkg\ fetch
@@ -26,6 +31,7 @@ before_build:
     -DCMAKE_GENERATOR_PLATFORM=x64
     -DLSQPACK_TESTS=ON
     -DLSQPACK_XXH=%LSQPACK_XXH%
+    -DCMAKE_%XXH_CMAKE%_FIND_PACKAGE_xxHash=ON
     -DGETOPT_INCLUDE_DIR=c:/tools/vcpkg/installed/x64-windows/include
     -DGETOPT_LIB=c:/tools/vcpkg/installed/x64-windows/lib/getopt.lib
 

CMakeLists.txt

@@ -37,10 +37,14 @@ if(LSQPACK_XXH)
     target_sources(ls-qpack PRIVATE deps/xxhash/xxhash.c)
     set(LSQPACK_DEPENDS "")
 else()
-	find_package(PkgConfig REQUIRED)
-	pkg_check_modules(XXH REQUIRED IMPORTED_TARGET libxxhash)
-	target_link_libraries(ls-qpack PUBLIC PkgConfig::XXH)
-	set(LSQPACK_DEPENDS "libxxhash")
+    find_package(xxHash CONFIG)
+    if(NOT xxHash_FOUND)
+        find_package(PkgConfig REQUIRED)
+        pkg_check_modules(LS_QPACK_XXH REQUIRED IMPORTED_TARGET libxxhash GLOBAL)
+        add_library(xxHash::xxhash ALIAS PkgConfig::LS_QPACK_XXH)
+    endif()
+    target_link_libraries(ls-qpack PRIVATE xxHash::xxhash)
+    set(LSQPACK_DEPENDS "libxxhash")
 endif()
 
 if(WIN32 OR EMSCRIPTEN)
@@ -128,10 +132,14 @@ configure_file(lsqpack.pc.in lsqpack.pc @ONLY)
 install(FILES "${CMAKE_CURRENT_BINARY_DIR}/lsqpack.pc"
     DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
 
+configure_file(ls-qpack-config.cmake.in ls-qpack-config.cmake @ONLY)
 install(TARGETS ls-qpack EXPORT ls-qpack-config
         LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR})
+install(FILES "${CMAKE_CURRENT_BINARY_DIR}/ls-qpack-config.cmake"
+    DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/ls-qpack)
 install(
     EXPORT ls-qpack-config
+    FILE ls-qpack-targets.cmake
     NAMESPACE ls-qpack::
     DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/ls-qpack
 )

bin/CMakeLists.txt

@@ -7,7 +7,7 @@ function(lsqpack_add_executable TARGET)
         target_include_directories(${TARGET} PRIVATE ../deps/xxhash)
     else()
         target_sources(${TARGET} PRIVATE ${TARGET}.c)
-        target_link_libraries(${TARGET} PUBLIC PkgConfig::XXH)
+        target_link_libraries(${TARGET} PUBLIC xxHash::xxhash)
     endif()
 
     if(WIN32)

ls-qpack-config.cmake.in

@@ -0,0 +1,10 @@
+if(NOT "@BUILD_SHARED_LIBS@" AND NOT "@LSQPACK_XXH@")
+    include(CMakeFindDependencyMacro)
+    if("@xxHash_FOUND@")
+        find_dependency(xxHash CONFIG)
+    else()
+        find_dependency(PkgConfig)
+        pkg_check_modules(XXH REQUIRED IMPORTED_TARGET libxxhash)
+    endif()
+endif()
+include("${CMAKE_CURRENT_LIST_DIR}/ls-qpack-targets.cmake")

test/CMakeLists.txt

@@ -1,11 +1,7 @@
 function(lsqpack_add_test TARGET)
     add_executable(test_${TARGET} "")
     target_sources(test_${TARGET} PRIVATE test_${TARGET}.c)
-    if(LSQPACK_XXH)
-        target_link_libraries(test_${TARGET} ls-qpack)
-    else()
-        target_link_libraries(test_${TARGET} ls-qpack PkgConfig::XXH)
-    endif()
+    target_link_libraries(test_${TARGET} ls-qpack)
 
     if(WIN32)
         target_include_directories(test_${TARGET} PRIVATE ../wincompat)