[clang] [llvm] [LLVM][Clang][Cygwin] Fix building Clang for Cygwin (PR #134494)

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Mateusz =?utf-8?q?Mikuła?= <oss at mateuszmikula.dev>,
Mateusz =?utf-8?q?Mikuła?= <oss at mateuszmikula.dev>,
Mateusz =?utf-8?q?Mikuła?= <oss at mateuszmikula.dev>,
Mateusz =?utf-8?q?Mikuła?= <oss at mateuszmikula.dev>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/134494 at github.com>


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Mateusz Mikuła (mati865)

<details>
<summary>Changes</summary>

With these changes, LLVM and Clang become buildable for Cygwin.

GCC config (using MSYS2 GCC):
`CFLAGS="-D_GNU_SOURCE=1" CXXFLAGS="-D_GNU_SOURCE=1" CPPFLAGS="-D_GNU_SOURCE=1" cmake -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-pc-cygwin -DLLVM_HOST_TRIPLE=x86_64-pc-cygwin -DLLVM_TARGETS_TO_BUILD="AArch64;X86" -DLIBCLANG_BUILD_STATIC=ON ../llvm`
`-D_GNU_SOURCE=1` is important because GCC on Cygwin, opposed to GCC on Linux, does not define it.

Clang config (using https://github.com/msys2/MSYS2-packages/pull/5308):
`CC=clang CXX=clang++ cmake -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-pc-cygwin -DLLVM_HOST_TRIPLE=x86_64-pc-cygwin -DLLVM_TARGETS_TO_BUILD="AArch64;X86" -DLIBCLANG_BUILD_STATIC=ON ../llvm`

Split out from https://github.com/llvm/llvm-project/pull/134458

---
Full diff: https://github.com/llvm/llvm-project/pull/134494.diff


5 Files Affected:

- (modified) clang/include/clang/Support/Compiler.h (+1-1) 
- (modified) clang/tools/CMakeLists.txt (+3-2) 
- (modified) clang/tools/libclang/CIndexer.cpp (-1) 
- (modified) clang/tools/libclang/CMakeLists.txt (+2-1) 
- (modified) llvm/lib/Support/Unix/Signals.inc (+1-1) 


``````````diff
diff --git a/clang/include/clang/Support/Compiler.h b/clang/include/clang/Support/Compiler.h
index 5a74f8e3b6723..e1ae3eda4ccc2 100644
--- a/clang/include/clang/Support/Compiler.h
+++ b/clang/include/clang/Support/Compiler.h
@@ -50,7 +50,7 @@
 #define CLANG_EXPORT_TEMPLATE
 #endif
 #elif defined(__ELF__) || defined(__MINGW32__) || defined(_AIX) ||             \
-    defined(__MVS__)
+    defined(__MVS__) || defined(__CYGWIN__)
 #define CLANG_ABI LLVM_ATTRIBUTE_VISIBILITY_DEFAULT
 #define CLANG_TEMPLATE_ABI LLVM_ATTRIBUTE_VISIBILITY_DEFAULT
 #define CLANG_EXPORT_TEMPLATE
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/CIndexer.cpp b/clang/tools/libclang/CIndexer.cpp
index 12d9d418dea51..1b9d58bc439ad 100644
--- a/clang/tools/libclang/CIndexer.cpp
+++ b/clang/tools/libclang/CIndexer.cpp
@@ -29,7 +29,6 @@
 #ifdef __CYGWIN__
 #include <cygwin/version.h>
 #include <sys/cygwin.h>
-#define _WIN32 1
 #endif
 
 #ifdef _WIN32
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()
 
diff --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
index 30e5f40193974..230763e729520 100644
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -847,7 +847,7 @@ void llvm::sys::PrintStackTrace(raw_ostream &OS, int Depth) {
 
     const char *name = strrchr(dlinfo.dli_fname, '/');
     if (!name)
-      OS << format(" %-*s", width, dlinfo.dli_fname);
+      OS << format(" %-*s", width, (const char *)dlinfo.dli_fname);
     else
       OS << format(" %-*s", width, name + 1);
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/134494