xdiff: move xdiff to 'deps'

xdiff is a dependency (from git core) and more properly belongs in the
'deps' directory. Move it there, and add a stub for cmake to resolve
xdiff from the system location in the future. (At present, bundled xdiff
remains hardcoded.)

CMakeLists.txt

@@ -36,6 +36,7 @@ option(USE_SHA1                "Enable SHA1. Can be set to CollisionDetection(ON
 option(USE_SHA256              "Enable SHA256. Can be set to HTTPS/Builtin" ON)
 option(USE_GSSAPI              "Link with libgssapi for SPNEGO auth"      OFF)
    set(USE_HTTP_PARSER         "" CACHE STRING "Specifies the HTTP Parser implementation; either system or builtin.")
+#  set(USE_XDIFF               "" CACHE STRING "Specifies the xdiff implementation; either system or builtin.")
    set(REGEX_BACKEND           "" CACHE STRING "Regular expression implementation. One of regcomp_l, pcre2, pcre, regcomp, or builtin.")
 option(USE_BUNDLED_ZLIB        "Use the bundled version of zlib. Can be set to one of Bundled(ON)/Chromium. The Chromium option requires a x86_64 processor with SSE4.2 and CLMUL" OFF)
 

cmake/SelectXdiff.cmake

+# Optional external dependency: xdiff
+if(USE_XDIFF STREQUAL "system")
+	message(FATAL_ERROR "external/system xdiff is not yet supported")
+else()
+	add_subdirectory("${PROJECT_SOURCE_DIR}/deps/xdiff" "${PROJECT_BINARY_DIR}/deps/xdiff")
+	list(APPEND LIBGIT2_DEPENDENCY_INCLUDES "${PROJECT_SOURCE_DIR}/deps/xdiff")
+	list(APPEND LIBGIT2_DEPENDENCY_OBJECTS "$<TARGET_OBJECTS:xdiff>")
+	add_feature_info(xdiff ON "xdiff support (bundled)")
+endif()

deps/xdiff/CMakeLists.txt

+
+file(GLOB SRC_XDIFF "*.c" "*.h")
+list(SORT SRC_XDIFF)
+
+add_library(xdiff OBJECT ${SRC_XDIFF})
+target_include_directories(xdiff SYSTEM PRIVATE
+	"${PROJECT_SOURCE_DIR}/include"
+	"${PROJECT_SOURCE_DIR}/src/util"
+	"${PROJECT_BINARY_DIR}/src/util"
+	${LIBGIT2_SYSTEM_INCLUDES}
+	${LIBGIT2_DEPENDENCY_INCLUDES})
+
+# the xdiff dependency is not (yet) warning-free, disable warnings
+# as errors for the xdiff sources until we've sorted them out
+if(MSVC)
+        set_source_files_properties(xdiffi.c PROPERTIES COMPILE_FLAGS -WX-)
+        set_source_files_properties(xemit.c PROPERTIES COMPILE_FLAGS -WX-)
+        set_source_files_properties(xhistogram.c PROPERTIES COMPILE_FLAGS -WX-)
+        set_source_files_properties(xmerge.c PROPERTIES COMPILE_FLAGS -WX-)
+        set_source_files_properties(xutils.c PROPERTIES COMPILE_FLAGS -WX-)
+        set_source_files_properties(xpatience.c PROPERTIES COMPILE_FLAGS -WX-)
+else()
+        set_source_files_properties(xdiffi.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare -Wno-unused-parameter")
+        set_source_files_properties(xemit.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare -Wno-unused-parameter")
+        set_source_files_properties(xhistogram.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
+        set_source_files_properties(xutils.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
+        set_source_files_properties(xpatience.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
+endif()

src/CMakeLists.txt

@@ -41,6 +41,7 @@ include(SelectHTTPSBackend)
 include(SelectHashes)
 include(SelectHTTPParser)
 include(SelectRegex)
+include(SelectXdiff)
 include(SelectSSH)
 include(SelectWinHTTP)
 include(SelectZlib)

src/libgit2/CMakeLists.txt

@@ -25,8 +25,7 @@ target_sources(libgit2 PRIVATE ${SRC_H})
 
 file(GLOB SRC_GIT2 *.c *.h
 	streams/*.c streams/*.h
-	transports/*.c transports/*.h
-	xdiff/*.c xdiff/*.h)
+	transports/*.c transports/*.h)
 list(SORT SRC_GIT2)
 target_sources(libgit2 PRIVATE ${SRC_GIT2})
 
@@ -40,23 +39,6 @@ if(APPLE)
 	set_source_files_properties(streams/stransport.c PROPERTIES COMPILE_FLAGS -Wno-deprecated)
 endif()
 
-# the xdiff dependency is not (yet) warning-free, disable warnings
-# as errors for the xdiff sources until we've sorted them out
-if(MSVC)
-	set_source_files_properties(xdiff/xdiffi.c PROPERTIES COMPILE_FLAGS -WX-)
-	set_source_files_properties(xdiff/xemit.c PROPERTIES COMPILE_FLAGS -WX-)
-	set_source_files_properties(xdiff/xhistogram.c PROPERTIES COMPILE_FLAGS -WX-)
-	set_source_files_properties(xdiff/xmerge.c PROPERTIES COMPILE_FLAGS -WX-)
-	set_source_files_properties(xdiff/xutils.c PROPERTIES COMPILE_FLAGS -WX-)
-	set_source_files_properties(xdiff/xpatience.c PROPERTIES COMPILE_FLAGS -WX-)
-else()
-	set_source_files_properties(xdiff/xdiffi.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare -Wno-unused-parameter")
-	set_source_files_properties(xdiff/xemit.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare -Wno-unused-parameter")
-	set_source_files_properties(xdiff/xhistogram.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
-	set_source_files_properties(xdiff/xutils.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
-	set_source_files_properties(xdiff/xpatience.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
-endif()
-
 ide_split_sources(libgit2)
 list(APPEND LIBGIT2_OBJECTS $<TARGET_OBJECTS:util> $<TARGET_OBJECTS:libgit2> ${LIBGIT2_DEPENDENCY_OBJECTS})
 list(APPEND LIBGIT2_INCLUDES ${LIBGIT2_DEPENDENCY_INCLUDES})

src/libgit2/blame_git.c

@@ -9,7 +9,6 @@
 
 #include "commit.h"
 #include "blob.h"
-#include "xdiff/xinclude.h"
 #include "diff_xdiff.h"
 
 /*

src/libgit2/diff_xdiff.h

@@ -10,7 +10,7 @@
 #include "common.h"
 
 #include "diff.h"
-#include "xdiff/xdiff.h"
+#include "xdiff.h"
 #include "patch_generate.h"
 
 /* xdiff cannot cope with large files.  these files should not be passed to

src/libgit2/merge_file.c

@@ -19,8 +19,6 @@
 #include "git2/index.h"
 #include "git2/merge.h"
 
-#include "xdiff/xdiff.h"
-
 /* only examine the first 8000 bytes for binaryness.
  * https://github.com/git/git/blob/77bd3ea9f54f1584147b594abc04c26ca516d987/xdiff-interface.c#L197
  */