From c56734017173d3d76e03f28ea2a16d4856899e22 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Tomulik?= <pawel@tomulik.pl>
Date: Wed, 19 Nov 2025 04:25:23 +0100
Subject: [PATCH] build: support Cygwin + bundled luajit #36417

Fixes compilation/link/installation on Cygwin with bundled dependencies
(cmake.deps). Only builds with LuaJIT are fixed. Linking against PUC LUA still
does not work.

Note: Luajit technically does not support Cygwin:
https://github.com/LuaJIT/LuaJIT/commit/55a42da36ea6dd357ef928dd5c6776278b32ab92
---
 cmake.deps/cmake/BuildLuajit.cmake | 29 ++++++++++++++++++++++++++++-
 src/nvim/CMakeLists.txt            | 12 +++++++++++-
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/cmake.deps/cmake/BuildLuajit.cmake b/cmake.deps/cmake/BuildLuajit.cmake
index c8a45b327f..070eeafc00 100644
--- a/cmake.deps/cmake/BuildLuajit.cmake
+++ b/cmake.deps/cmake/BuildLuajit.cmake
@@ -41,7 +41,34 @@ if(APPLE)
   set(DEPLOYMENT_TARGET "MACOSX_DEPLOYMENT_TARGET=${CMAKE_OSX_DEPLOYMENT_TARGET}")
 endif()
 
-if(UNIX)
+if(CYGWIN)
+  if(CMAKE_GENERATOR MATCHES "Ninja")
+    set(LUAJIT_MAKE_PRG ${MAKE_PRG})
+  else()
+    set(LUAJIT_MAKE_PRG ${CMAKE_MAKE_PROGRAM})
+  endif()
+  BuildLuajit(BUILD_COMMAND ${LUAJIT_MAKE_PRG} CC=${DEPS_C_COMPILER}
+                                PREFIX=${DEPS_INSTALL_DIR}
+                                CFLAGS+=-DLUA_USE_APICHECK
+                                CFLAGS+=-funwind-tables
+                                CCDEBUG+=-g
+                                BUILDMODE=static
+                      # Build a DLL too
+                      COMMAND ${LUAJIT_MAKE_PRG} CC=${DEPS_C_COMPILER} BUILDMODE=dynamic
+
+          INSTALL_COMMAND ${CMAKE_COMMAND} -E make_directory ${DEPS_BIN_DIR}
+	    COMMAND ${CMAKE_COMMAND} -E copy ${DEPS_BUILD_DIR}/src/luajit/src/luajit.exe ${DEPS_BIN_DIR}
+	    COMMAND ${CMAKE_COMMAND} -E copy ${DEPS_BUILD_DIR}/src/luajit/src/cyglua51.dll ${DEPS_BIN_DIR}
+	    COMMAND ${CMAKE_COMMAND} -E make_directory ${DEPS_LIB_DIR}
+	    # Luarocks searches for lua51.dll in lib
+	    COMMAND ${CMAKE_COMMAND} -E copy ${DEPS_BUILD_DIR}/src/luajit/src/cyglua51.dll ${DEPS_LIB_DIR}
+	    COMMAND ${CMAKE_COMMAND} -E copy ${DEPS_BUILD_DIR}/src/luajit/src/libluajit-5.1.dll.a ${DEPS_LIB_DIR}
+	    COMMAND ${CMAKE_COMMAND} -E make_directory ${DEPS_INSTALL_DIR}/include/luajit-2.1
+	    COMMAND ${CMAKE_COMMAND} -DFROM_GLOB=${DEPS_BUILD_DIR}/src/luajit/src/*.h -DTO=${DEPS_INSTALL_DIR}/include/luajit-2.1 -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/CopyFilesGlob.cmake
+            COMMAND ${CMAKE_COMMAND} -E copy_directory ${DEPS_BUILD_DIR}/src/luajit/src/jit ${DEPS_INSTALL_DIR}/share/luajit-2.1/jit
+	    )
+
+elseif(UNIX)
   BuildLuajit(INSTALL_COMMAND ${BUILDCMD_UNIX}
     CC=${DEPS_C_COMPILER} PREFIX=${DEPS_INSTALL_DIR}
     ${DEPLOYMENT_TARGET} install)
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index c9a354ddbd..d254b1d4ac 100644
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -72,7 +72,7 @@ else()
   target_include_directories(main_lib SYSTEM BEFORE INTERFACE ${LUAJIT_INCLUDE_DIR})
   target_link_libraries(main_lib INTERFACE ${LUAJIT_LIBRARY})
   target_include_directories(nlua0 SYSTEM BEFORE PUBLIC ${LUAJIT_INCLUDE_DIR})
-  if(WIN32)
+  if(WIN32 OR CYGWIN)
     target_link_libraries(nlua0 PUBLIC ${LUAJIT_LIBRARY})
   endif()
 endif()
@@ -816,6 +816,16 @@ if(EXISTS ${DEPS_PREFIX}/lib/nvim/parser)
     COMMAND ${CMAKE_COMMAND} -E ${COPY_DIRECTORY} ${DEPS_PREFIX}/lib/nvim/parser ${BINARY_LIB_DIR}/parser)
 endif()
 
+if(CYGWIN)
+  if(NOT PREFER_LUA)
+    add_custom_command(
+      TARGET nvim_runtime_deps
+      POST_BUILD
+      COMMAND ${CMAKE_COMMAND} -E copy ${DEPS_PREFIX}/bin/cyglua51.dll ${PROJECT_BINARY_DIR}/bin)
+    install(PROGRAMS ${PROJECT_BINARY_DIR}/bin/cyglua51.dll DESTINATION ${CMAKE_INSTALL_BINDIR})
+  endif()
+endif()
+
 install(DIRECTORY ${BINARY_LIB_DIR}
   DESTINATION ${CMAKE_INSTALL_LIBDIR}
   USE_SOURCE_PERMISSIONS)