[ELF] Define NOMINMAX to fix zlib.h caused build failure on Windows

[yxsamliu]

On Windows when zlib is enabled, zlib header introduced some Windows headers which defines max as a macro. Since OutputSections.cpp uses std::max with template argument, this causes compilation error.

Define macro NOMINMAX to avoid this.

[llvmbot]

@llvm/pr-subscribers-lld-elf

@llvm/pr-subscribers-lld

Author: Yaxun (Sam) Liu (yxsamliu)

Changes

On Windows when zlib is enabled, zlib header introduced some C headers which defines max as a macro. Since OutputSections.cpp uses std::max with template argument, this causes compilation error.

Undefine max to workaround this issue.

---

Full diff: https://github.com/llvm/llvm-project/pull/70368.diff

1 Files Affected:

• (modified) lld/ELF/OutputSections.cpp (+5)

diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index 2dc425927109403..df78075fee6972e 100644
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -23,6 +23,11 @@
 #include "llvm/Support/TimeProfiler.h"
 #if LLVM_ENABLE_ZLIB
 #include <zlib.h>
+// zlib 1.2.13 causes max to be defined as a macro on Windows.
+// undefine it to use std::max.
+#ifdef max
+#undef max
+#endif
 #endif
 #if LLVM_ENABLE_ZSTD
 #include <zstd.h>

[MaskRay]

I think zlib is often disabled on Windows, so nobody has noticed for such a long time.

On Windows when zlib is enabled, zlib header introduced some C headers which defines max as a macro. Since OutputSections.cpp uses std::max with template argument, this causes compilation error.

Can you point out where max is defined in zlib v2.3.13? A likely better choice is to disable zlib for Windows if a problematic one is found.

[yxsamliu]

I think zlib is often disabled on Windows, so nobody has noticed for such a long time.

On Windows when zlib is enabled, zlib header introduced some C headers which defines max as a macro. Since OutputSections.cpp uses std::max with template argument, this causes compilation error.

Can you point out where max is defined in zlib v2.3.13? A likely better choice is to disable zlib for Windows if a problematic one is found.

zlib header does not define max as a macro, but it includes some windows headers which define max as macro. There is a cleaner way to avoid that by defining a macro NOMINMAX before include zlib.h.

[yxsamliu]

ping

[MaskRay]

// Avoid introducing max as a macro from windows.h on Windows.

[MaskRay]

Thanks. The original title was not very clear. I have changed it to
[ELF] Define NOMINMAX to fix zlib.h caused build failure on Windows