From aa78827db2931d5affa13c5612f821e1328ec5ac Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Tue, 10 Oct 2017 18:04:02 -0400
Subject: [PATCH] add module flag to emit CodeView for COFF object files

see #516
---
 README.md        | 4 ++++
 src/codegen.cpp  | 6 +++++-
 src/zig_llvm.cpp | 4 ++++
 src/zig_llvm.hpp | 1 +
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 8cbf31b3e144..a28da25e54ed 100644
--- a/README.md
+++ b/README.md
@@ -189,6 +189,10 @@ make install
 ./zig build --build-file ../build.zig test
 ```
 
+#### Windows
+
+See https://github.com/zig-lang/zig/wiki/Building-Zig-on-Windows
+
 ### Release / Install Build
 
 Once installed, `ZIG_LIBC_LIB_DIR` and `ZIG_LIBC_INCLUDE_DIR` can be overridden
diff --git a/src/codegen.cpp b/src/codegen.cpp
index 5889ba316a78..03fa976b2e4c 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -4992,7 +4992,11 @@ static void init(CodeGen *g) {
 
     LLVMSetTarget(g->module, buf_ptr(&g->triple_str));
 
-    ZigLLVMAddModuleDebugInfoFlag(g->module);
+    if (g->zig_target.oformat == ZigLLVM_COFF) {
+        ZigLLVMAddModuleCodeViewFlag(g->module);
+    } else {
+        ZigLLVMAddModuleDebugInfoFlag(g->module);
+    }
 
     LLVMTargetRef target_ref;
     char *err_msg = nullptr;
diff --git a/src/zig_llvm.cpp b/src/zig_llvm.cpp
index b9f1f7b92fa2..5d8b34de1020 100644
--- a/src/zig_llvm.cpp
+++ b/src/zig_llvm.cpp
@@ -706,6 +706,10 @@ void ZigLLVMAddModuleDebugInfoFlag(LLVMModuleRef module) {
     unwrap(module)->addModuleFlag(Module::Warning, "Debug Info Version", DEBUG_METADATA_VERSION);
 }
 
+void ZigLLVMAddModuleCodeViewFlag(LLVMModuleRef module) {
+    unwrap(module)->addModuleFlag(Module::Warning, "CodeView", 1);
+}
+
 static AtomicOrdering mapFromLLVMOrdering(LLVMAtomicOrdering Ordering) {
     switch (Ordering) {
         case LLVMAtomicOrderingNotAtomic: return AtomicOrdering::NotAtomic;
diff --git a/src/zig_llvm.hpp b/src/zig_llvm.hpp
index 114c75775b28..e8df900a10fb 100644
--- a/src/zig_llvm.hpp
+++ b/src/zig_llvm.hpp
@@ -112,6 +112,7 @@ unsigned ZigLLVMTag_DW_structure_type(void);
 
 ZigLLVMDIBuilder *ZigLLVMCreateDIBuilder(LLVMModuleRef module, bool allow_unresolved);
 void ZigLLVMAddModuleDebugInfoFlag(LLVMModuleRef module);
+void ZigLLVMAddModuleCodeViewFlag(LLVMModuleRef module);
 
 void ZigLLVMSetCurrentDebugLocation(LLVMBuilderRef builder, int line, int column, ZigLLVMDIScope *scope);
 void ZigLLVMClearCurrentDebugLocation(LLVMBuilderRef builder);