build: remove SWIFT_NEED_EXPLICIT_LIBDISPATCH (NFC)

This flag was being used as an alias for whether or not the host is
non-Darwin.  Rather than adding custom checks for this, use the explicit
check that CMake supports.  This simplifies the logic and avoids the
proliferation of custom variables which can become confusing for others
who are not familiar with the custom build infrastructure.

Author: compnerd

Diff for: CMakeLists.txt

@@ -465,10 +465,7 @@ option(SWIFT_BUILD_SOURCEKIT "Build SourceKit" TRUE)
 option(SWIFT_ENABLE_SOURCEKIT_TESTS "Enable running SourceKit tests" ${SWIFT_BUILD_SOURCEKIT})
 
 if(SWIFT_BUILD_SYNTAXPARSERLIB OR SWIFT_BUILD_SOURCEKIT)
-  if(CMAKE_SYSTEM_NAME STREQUAL Darwin)
-    set(SWIFT_NEED_EXPLICIT_LIBDISPATCH FALSE)
-  else()
-    set(SWIFT_NEED_EXPLICIT_LIBDISPATCH TRUE)
+  if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
     if(NOT EXISTS "${SWIFT_PATH_TO_LIBDISPATCH_SOURCE}")
       message(SEND_ERROR "SyntaxParserLib and SourceKit require libdispatch on non-Darwin hosts.  Please specify SWIFT_PATH_TO_LIBDISPATCH_SOURCE")
     endif()
@@ -954,7 +951,7 @@ if (LLVM_ENABLE_DOXYGEN)
   message(STATUS "Doxygen: enabled")
 endif()
 
-if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
   if(CMAKE_C_COMPILER_ID STREQUAL Clang AND
      CMAKE_C_COMPILER_VERSION VERSION_GREATER 3.8
      OR LLVM_USE_SANITIZER)

Diff for: tools/SourceKit/lib/Support/CMakeLists.txt

@@ -11,7 +11,9 @@ target_link_libraries(SourceKitSupport PRIVATE
   swiftSyntax
   clangBasic
   clangRewrite)
-if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
-  target_link_libraries(SourceKitSupport INTERFACE dispatch BlocksRuntime)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(SourceKitSupport INTERFACE
+    dispatch
+    BlocksRuntime)
 endif()
 

Diff for: tools/SourceKit/tools/complete-test/CMakeLists.txt

@@ -7,8 +7,10 @@ if(SWIFT_SOURCEKIT_USE_INPROC_LIBRARY)
 else()
   target_link_libraries(complete-test PRIVATE sourcekitd)
 endif()
-if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
-  target_link_libraries(complete-test PRIVATE dispatch BlocksRuntime)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(complete-test PRIVATE
+    dispatch
+    BlocksRuntime)
 endif()
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")

Diff for: tools/SourceKit/tools/sourcekitd-repl/CMakeLists.txt

@@ -12,8 +12,10 @@ if(HAVE_UNICODE_LIBEDIT)
   else()
     target_link_libraries(sourcekitd-repl PRIVATE sourcekitd)
   endif()
-  if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
-    target_link_libraries(sourcekitd-repl PRIVATE dispatch BlocksRuntime)
+  if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+    target_link_libraries(sourcekitd-repl PRIVATE
+      dispatch
+      BlocksRuntime)
   endif()
 
   if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")

Diff for: tools/SourceKit/tools/sourcekitd-test/CMakeLists.txt

@@ -17,8 +17,10 @@ if(SWIFT_SOURCEKIT_USE_INPROC_LIBRARY)
 else()
   target_link_libraries(sourcekitd-test PRIVATE sourcekitd)
 endif()
-if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
-  target_link_libraries(sourcekitd-test PRIVATE dispatch BlocksRuntime)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(sourcekitd-test PRIVATE
+    dispatch
+    BlocksRuntime)
 endif()
 
 add_dependencies(sourcekitd-test sourcekitdTestOptionsTableGen)

Diff for: tools/libSwiftSyntaxParser/CMakeLists.txt

@@ -45,8 +45,9 @@ endif()
 
 set_property(TARGET libSwiftSyntaxParser APPEND_STRING PROPERTY
   COMPILE_FLAGS " -fblocks")
-if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
-  target_link_libraries(libSwiftSyntaxParser PRIVATE BlocksRuntime)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(libSwiftSyntaxParser PRIVATE
+    BlocksRuntime)
 endif()
 
 add_dependencies(parser-lib libSwiftSyntaxParser)

Diff for: tools/swift-syntax-parser-test/CMakeLists.txt

@@ -27,6 +27,7 @@ endif()
 
 set_property(TARGET swift-syntax-parser-test APPEND_STRING PROPERTY
   COMPILE_FLAGS " -fblocks")
-if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
-  target_link_libraries(swift-syntax-parser-test PRIVATE BlocksRuntime)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(swift-syntax-parser-test PRIVATE
+    BlocksRuntime)
 endif()

Diff for: unittests/SyntaxParser/CMakeLists.txt

@@ -24,6 +24,7 @@ endif()
 
 set_property(TARGET SwiftSyntaxParserTests APPEND_STRING PROPERTY
   COMPILE_FLAGS " -fblocks")
-if(SWIFT_NEED_EXPLICIT_LIBDISPATCH)
-  target_link_libraries(SwiftSyntaxParserTests PRIVATE BlocksRuntime)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(SwiftSyntaxParserTests PRIVATE
+    BlocksRuntime)
 endif()