[clang] [Win32][ELF] Make CodeView a DebugInfoFormat only for COFF format (PR #87149)

[Phoebe Wang via cfe-commits]

https://github.com/phoebewang created https://github.com/llvm/llvm-project/pull/87149

We have many problems to use CodeView for a win32-elf target, e.g., #87140 and `error: .seh_* directives are not supported on this target`.

Fixes: #87140

>From 745b2acb9dafbb54b00353f71dee464b3617c13a Mon Sep 17 00:00:00 2001
From: Phoebe Wang <phoebe.wang at intel.com>
Date: Sat, 30 Mar 2024 17:29:06 +0800
Subject: [PATCH] [Win32][ELF] Make CodeView a DebugInfoFormat only for COFF
 format

We have many problems to use CodeView for a win32-elf target, e.g., #87140
and `error: .seh_* directives are not supported on this target`.

Fixes: #87140
---
 clang/lib/Driver/ToolChains/MSVC.h | 6 +++---
 clang/test/Misc/win32-elf.c        | 5 +++++
 2 files changed, 8 insertions(+), 3 deletions(-)
 create mode 100644 clang/test/Misc/win32-elf.c

diff --git a/clang/lib/Driver/ToolChains/MSVC.h b/clang/lib/Driver/ToolChains/MSVC.h
index 48369e030aade2..3a5975272c570f 100644
--- a/clang/lib/Driver/ToolChains/MSVC.h
+++ b/clang/lib/Driver/ToolChains/MSVC.h
@@ -61,9 +61,9 @@ class LLVM_LIBRARY_VISIBILITY MSVCToolChain : public ToolChain {
   /// formats, and to DWARF otherwise. Users can use -gcodeview and -gdwarf to
   /// override the default.
   llvm::codegenoptions::DebugInfoFormat getDefaultDebugFormat() const override {
-    return getTriple().isOSBinFormatMachO()
-               ? llvm::codegenoptions::DIF_DWARF
-               : llvm::codegenoptions::DIF_CodeView;
+    return getTriple().isOSBinFormatCOFF()
+               ? llvm::codegenoptions::DIF_CodeView
+               : llvm::codegenoptions::DIF_DWARF;
   }
 
   /// Set the debugger tuning to "default", since we're definitely not tuning
diff --git a/clang/test/Misc/win32-elf.c b/clang/test/Misc/win32-elf.c
new file mode 100644
index 00000000000000..f75281dc418727
--- /dev/null
+++ b/clang/test/Misc/win32-elf.c
@@ -0,0 +1,5 @@
+// Check that basic use of win32-elf targets works.
+// RUN: %clang -fsyntax-only -target x86_64-pc-win32-elf %s
+
+// RUN: %clang -fsyntax-only -target x86_64-pc-win32-elf -g %s -### 2>&1 | FileCheck %s -check-prefix=DEBUG-INFO
+// DEBUG-INFO: -dwarf-version={{.*}}