https://github.com/kikairoya created
https://github.com/llvm/llvm-project/pull/147132
On Cygwin, a shared library target generates a versioned DLL file like
`cyg${OUTPUT_NAME}-${VERSION}.dll` and an import library
`lib${OUTPUT_NAME}.dll.a`, but it does *not* generate the expected unversioned
symlink `cyg${OUTPUT_NAME}.dll` as is typical on other Unix-like platforms.
However, `dlopen()` calls typically use the unversioned form (e.g.
`cygclang.dll`), and this is consistent with usage on other platforms. In
particular, `clang-python` relies on this behavior. Although the Cygwin runtime
can resolve other forms like `libclang.so` or `libclang.dll`, a symlink alone
won't suffice here, as `dlopen()` ultimately calls `LoadLibraryExW`, which does
not follow Cygwin-style symlinks.
Therefore, this patch installs an unversioned copy of the DLL without the
version suffix to improve compatibility with `dlopen()` and tools like
`clang-python`.
>From 9198e98e6dd7a02c5c5b65e400d788b6bac3a3c3 Mon Sep 17 00:00:00 2001
From: kikairoya <[email protected]>
Date: Sat, 28 Jun 2025 13:11:42 +0900
Subject: [PATCH] [libclang][Cygwin] Put unversioned DLL file aside of
versioned DLL file
On Cygwin, a shared library target generates a versioned DLL file like
"cyg${OUTPUT_NAME}-${VERSION}.dll" and an import library
"lib${OUTPUT_NAME}.dll.a", but it does *not* generate the expected
unversioned symlink "cyg${OUTPUT_NAME}.dll" as is typical on other Unix-like
platforms.
However, `dlopen()` calls typically use the unversioned form (e.g.
"cygclang.dll"),
and this is consistent with usage on other platforms. In particular,
`clang-python`
relies on this behavior. Although the Cygwin runtime can resolve other forms
like
"libclang.so" or "libclang.dll", a symlink alone won't suffice here, as
`dlopen()`
ultimately calls `LoadLibraryExW`, which does not follow Cygwin-style symlinks.
Therefore, this patch installs an unversioned copy of the DLL without the
version
suffix to improve compatibility with `dlopen()` and tools like `clang-python`.
---
clang/tools/libclang/CMakeLists.txt | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/clang/tools/libclang/CMakeLists.txt
b/clang/tools/libclang/CMakeLists.txt
index ac7a9a8db37c0..9c5ca26aab099 100644
--- a/clang/tools/libclang/CMakeLists.txt
+++ b/clang/tools/libclang/CMakeLists.txt
@@ -157,15 +157,28 @@ if(ENABLE_STATIC)
endif()
if(ENABLE_SHARED)
- if(WIN32)
+ if(WIN32 OR CYGWIN)
set_target_properties(libclang
PROPERTIES
VERSION ${LIBCLANG_LIBRARY_VERSION}
DEFINE_SYMBOL _CINDEX_LIB_)
- # Avoid declaring clang c++ symbols that are statically linked into
libclang as dllimport'ed.
- # If llvm/libclang-cpp dll is also being built for windows clang c++
symbols will still be
- # implicitly be exported from libclang.
- target_compile_definitions(libclang PRIVATE CLANG_BUILD_STATIC)
+ if (CYGWIN)
+ # On Cygwin environment, a library target generates
"cyg${OUTPUT_NAME}-${VERSION}.dll" and "lib${OUTPUT_NAME}.dll.a" but
+ # don't provide link "cyg${OUTPUT_NAME}.dll" differs from expected as
other Unix platforms.
+ # Although, to dlopen(), usually "cyg${OUTPUT_NAME}.dll" will be passed
(or "lib${OUTPUT_NAME}.dll" and "lib${OUTPUT_NAME}.so"
+ # are also viable as Cygwin runtime replaces those prefix and suffix),
which is same manner to other Unix platforms,
+ # and clang-python does so.
+ # Thus, put a copy of dll named without version suffix to convinience to
use of dlopen(). A symbolic link can't be
+ # viable here as the path passed to dlopen() will be passed directly to
LoadLibraryExW, so it must be a real file.
+ set(UNPAINTED_TARGET_NAME
"$<TARGET_FILE_DIR:libclang>/$<TARGET_FILE_PREFIX:libclang>clang$<TARGET_FILE_SUFFIX:libclang>")
+ add_custom_command(TARGET libclang POST_BUILD
+ COMMAND ${CMAKE_COMMAND} -E copy
"$<TARGET_FILE:libclang>" "${UNPAINTED_TARGET_NAME}")
+ install(FILES "${UNPAINTED_TARGET_NAME}" DESTINATION
"${CMAKE_INSTALL_BINDIR}" COMPONENT libclang)
+ endif()
+ # Avoid declaring clang c++ symbols that are statically linked into
libclang as dllimport'ed.
+ # If llvm/libclang-cpp dll is also being built for windows clang c++
symbols will still be
+ # implicitly be exported from libclang.
+ target_compile_definitions(libclang PRIVATE CLANG_BUILD_STATIC)
elseif(APPLE)
set(LIBCLANG_LINK_FLAGS " -Wl,-compatibility_version -Wl,1")
set(LIBCLANG_LINK_FLAGS "${LIBCLANG_LINK_FLAGS} -Wl,-current_version
-Wl,${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
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