[clang] [Clang][Cygwin] Disable shared libs on Cygwin by default (PR #138119)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Mateusz Mikuła (mati865)

<details>
<summary>Changes</summary>

This change follows MinGW decisions, otherwise build with GCC fail with:
```
FAILED: bin/msys-clang-cpp-21.0git.dll lib/libclang-cpp.dll.a
...
/usr/lib/gcc/x86_64-pc-msys/13.3.0/../../../../x86_64-pc-msys/bin/ld: error: export ordinal too large: 92250
```

Split out from https://github.com/llvm/llvm-project/pull/134494

---
Full diff: https://github.com/llvm/llvm-project/pull/138119.diff


2 Files Affected:

- (modified) clang/tools/CMakeLists.txt (+3-2) 
- (modified) clang/tools/libclang/CMakeLists.txt (+2-1) 


``````````diff
diff --git a/clang/tools/CMakeLists.txt b/clang/tools/CMakeLists.txt
index 9634eb12080c8..50e3d694236ac 100644
--- a/clang/tools/CMakeLists.txt
+++ b/clang/tools/CMakeLists.txt
@@ -26,9 +26,10 @@ endif()
 add_clang_subdirectory(c-index-test)
 
 add_clang_subdirectory(clang-refactor)
-# For MinGW we only enable shared library if LLVM_LINK_LLVM_DYLIB=ON.
+# For MinGW/Cygwin we only enable shared library if LLVM_LINK_LLVM_DYLIB=ON.
 # Without that option resulting library is too close to 2^16 DLL exports limit.
-if(UNIX OR (MSVC AND LLVM_BUILD_LLVM_DYLIB_VIS) OR (MINGW AND LLVM_LINK_LLVM_DYLIB))
+if((UNIX AND NOT CYGWIN) OR (MSVC AND LLVM_BUILD_LLVM_DYLIB_VIS) OR
+  ((MINGW OR CYGWIN) AND LLVM_LINK_LLVM_DYLIB))
   add_clang_subdirectory(clang-shlib)
 endif()
 
diff --git a/clang/tools/libclang/CMakeLists.txt b/clang/tools/libclang/CMakeLists.txt
index 299c14660f3d4..37a939ffcada7 100644
--- a/clang/tools/libclang/CMakeLists.txt
+++ b/clang/tools/libclang/CMakeLists.txt
@@ -106,7 +106,8 @@ if (LLVM_EXPORTED_SYMBOL_FILE)
                      DEPENDS ${LIBCLANG_VERSION_SCRIPT_FILE})
 endif()
 
-if(LLVM_ENABLE_PIC OR (WIN32 AND NOT LIBCLANG_BUILD_STATIC))
+if((NOT (WIN32 OR CYGWIN) AND LLVM_ENABLE_PIC) OR
+  ((WIN32 OR CYGWIN) AND NOT LIBCLANG_BUILD_STATIC))
   set(ENABLE_SHARED SHARED)
 endif()
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/138119