[libunwind] Make sure __STDC_FORMAT_MACROS is defined to ensure PRId64 is available

[Zentrik]

See #102980 for further details.

[llvmbot]

@llvm/pr-subscribers-libunwind

Author: None (Zentrik)

Changes

See #102980 for further details.

---

Full diff: https://github.com/llvm/llvm-project/pull/117491.diff

1 Files Affected:

• (modified) libunwind/src/DwarfParser.hpp (+4)

diff --git a/libunwind/src/DwarfParser.hpp b/libunwind/src/DwarfParser.hpp
index 7e85025dd054d5..54357f56494330 100644
--- a/libunwind/src/DwarfParser.hpp
+++ b/libunwind/src/DwarfParser.hpp
@@ -12,6 +12,10 @@
 #ifndef __DWARF_PARSER_HPP__
 #define __DWARF_PARSER_HPP__
 
+#ifndef __STDC_FORMAT_MACROS
+// Ensure PRId64 macro is available
+#define __STDC_FORMAT_MACROS 1
+#endif
 #include <inttypes.h>
 #include <stdint.h>
 #include <stdio.h>

[Zentrik]

@ldionne Do you mind merging this as I don't have commit rights. Thank you

[MaskRay]

What old GCC versions need this? If it's just GCC 8, it's possible that we will drop GCC buildability soon. I think for runtime libraries we could pose a stricter requirement.

[ldionne]

Ah, I didn't realize this was only required for much older compilers. In that case, indeed we don't support GCC 8 so we probably don't want to merge this.

[giordano]

Based on https://github.com/JuliaPackaging/Yggdrasil/pull/9861/files#diff-812a6db0df5a0d42010930d41a801e33e89c6064172903e5aacb88a7c704def2R7 this came up with gcc 10

[Zentrik]

Based on WAVM/WAVM#266 (comment) and https://en.cppreference.com/w/cpp/types/integer#Notes this might have been fixed in glibc 2.18.

[ldionne]

Since we support only the latest released GCC in the runtimes, so I don't think it makes sense to merge this. Newer GCCs don't seem to have this issue.

Closing, please reopen if you'd like to pursue this despite the above information and we can chat.