[Cygwin] CYGWIN is not WIN32 in current CMake (#143130)

On old CMake, Cygwin were also WIN32 but currently not. LLVM_ON_UNIX=1
and LLVM_HAVE_LINK_VERSION_SCRIPT=0 should be defined for Cygwin target.

Author: kikairoya

llvm/cmake/config-ix.cmake

@@ -1,8 +1,3 @@
-if( WIN32 AND NOT CYGWIN )
-  # We consider Cygwin as another Unix
-  set(PURE_WINDOWS 1)
-endif()
-
 include(CheckIncludeFile)
 include(CheckLibraryExists)
 include(CheckSymbolExists)
@@ -31,7 +26,7 @@ elseif (APPLE)
   set(HAVE_SYS_MMAN_H 1)
   set(HAVE_SYSEXITS_H 1)
   set(HAVE_UNISTD_H 1)
-elseif (PURE_WINDOWS)
+elseif (WIN32)
   set(HAVE_MACH_MACH_H 0)
   set(HAVE_MALLOC_MALLOC_H 0)
   set(HAVE_PTHREAD_H 0)
@@ -132,7 +127,7 @@ if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
 endif()
 
 # library checks
-if( NOT PURE_WINDOWS )
+if(NOT WIN32)
   check_library_exists(pthread pthread_create "" HAVE_LIBPTHREAD)
   if (HAVE_LIBPTHREAD)
     check_library_exists(pthread pthread_rwlock_init "" HAVE_PTHREAD_RWLOCK_INIT)
@@ -275,7 +270,7 @@ endif()
 # party code may call MSan interceptors like strlen, leading to false positives.
 if(NOT LLVM_USE_SANITIZER MATCHES "Memory.*")
   # Don't look for these libraries on Windows.
-  if (NOT PURE_WINDOWS)
+  if (NOT WIN32)
     # Skip libedit if using ASan as it contains memory leaks.
     if (LLVM_ENABLE_LIBEDIT AND NOT LLVM_USE_SANITIZER MATCHES ".*Address.*")
       if(LLVM_ENABLE_LIBEDIT STREQUAL FORCE_ON)
@@ -384,7 +379,7 @@ check_symbol_exists(sbrk unistd.h HAVE_SBRK)
 check_symbol_exists(strerror_r string.h HAVE_STRERROR_R)
 check_symbol_exists(strerror_s string.h HAVE_DECL_STRERROR_S)
 check_symbol_exists(setenv stdlib.h HAVE_SETENV)
-if( PURE_WINDOWS )
+if(WIN32)
   check_symbol_exists(_chsize_s io.h HAVE__CHSIZE_S)
 
   check_function_exists(_alloca HAVE__ALLOCA)
@@ -420,8 +415,7 @@ else()
       "sys/types.h;sys/stat.h" HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC)
 endif()
 
-# This check requires _GNU_SOURCE.
-if (NOT PURE_WINDOWS)
+if (NOT WIN32)
   if (LLVM_PTHREAD_LIB)
     list(APPEND CMAKE_REQUIRED_LIBRARIES ${LLVM_PTHREAD_LIB})
   endif()

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -217,15 +217,15 @@ if( LLVM_REVERSE_ITERATION )
   set( LLVM_ENABLE_REVERSE_ITERATION 1 )
 endif()
 
-if(WIN32)
+if(WIN32 OR CYGWIN)
   set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
   if(CYGWIN)
     set(LLVM_ON_WIN32 0)
     set(LLVM_ON_UNIX 1)
-  else(CYGWIN)
+  else()
     set(LLVM_ON_WIN32 1)
     set(LLVM_ON_UNIX 0)
-  endif(CYGWIN)
+  endif()
 elseif(FUCHSIA OR UNIX)
   set(LLVM_ON_WIN32 0)
   set(LLVM_ON_UNIX 1)