Change:
In and it is described that to get working on a Linux kernel build, you should do: Inside that shell though, to build the kernel breaks with . Removing from the list fixes the issue. Why is that happening? If we can't fix it, we should at least update the wiki and manual. Full repro with and nixpkgs commit :
Seems to be caused by this change in the kernel: With this recent change, the kernel tries to use to find include and library flags for libelf, and fails back to the old behavior of assuming it's available in the default include/library directories. Running within shows something like: . These are flags so the compiler does not treat them like system includes and does not inhibit warnings from these headers. Making available makes the kernel use those flags, so libelf is included normally, leading to the warning and error, presumably because some kernel makefile adds to compiler flags. Without available, the libelf headers are found through include paths automatically by which are flags so warnings from those headers are ignored. I see different ways to fix this: Patch the libelf file to use instead of . Patch libelf headers to not produce those warnings. Patch the kernel to disable those warnings before including libelf (and re-enable). Any opinions?
is it normal for libelf headers to generate these warnings ? isn't that an upstream issue in some way ? I would vote for 2 ("fix libelf headers") since other approaches have their downsides: patching libelf's .pc may hide warnings for normal packages as I sometimes develop on the kernel, the more we patch its sourcecode, the more annoyed I get (pollutes git status etc.)
I'd agree that it's an upstream bug. Ran into this on my Gentoo system earlier, noticed something about those headers, and figured I'd chime in: they should be using instead of Relatively simple change, should fix the problem entirely. Edit: I'll try to send a patch upstream tomorrow or Friday. Uh, that is, today or Friday. It's past midnight. Oops.

Discussion:
patches = [ ./dont-hardcode-ar.patch <ins> # Fix warnings from preprocessor instructions. # https://github.com/NixOS/nixpkgs/issues/59929 ./preprocessor-warnings.patch </ins> ]; doCheck = true;

<ins> diff --git a/lib/elf_repl.h b/lib/elf_repl.h index c5cf90f..7e1e8df 100644 --- a/lib/elf_repl.h +++ b/lib/elf_repl.h @@ -45,7 +45,7 @@ typedef __libelf_u32_t		Elf32_Word; #define ELF32_FSZ_SWORD		4 #define ELF32_FSZ_WORD		4 -#if __LIBELF64 +#if defined(__LIBELF64) typedef __libelf_u64_t		Elf64_Addr; typedef __libelf_u16_t		Elf64_Half; @@ -93,7 +93,7 @@ typedef struct { Elf32_Half		e_shstrndx; } Elf32_Ehdr; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { unsigned char	e_ident[EI_NIDENT]; Elf64_Half		e_type; @@ -307,7 +307,7 @@ typedef struct { Elf32_Word		sh_entsize; } Elf32_Shdr; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Word		sh_name; Elf64_Word		sh_type; @@ -434,7 +434,7 @@ typedef struct { Elf32_Half		st_shndx; } Elf32_Sym; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Word		st_name; unsigned char	st_info; @@ -457,7 +457,7 @@ typedef struct { #define ELF32_ST_TYPE(i)	((i)&0xf) #define ELF32_ST_INFO(b,t)	(((b)<<4)+((t)&0xf)) -#if __LIBELF64 +#if defined(__LIBELF64) #define ELF64_ST_BIND(i)	((i)>>4) #define ELF64_ST_TYPE(i)	((i)&0xf) #define ELF64_ST_INFO(b,t)	(((b)<<4)+((t)&0xf)) @@ -495,7 +495,7 @@ typedef struct { * Macros for manipulating st_other */ #define ELF32_ST_VISIBILITY(o)	((o)&0x3) -#if __LIBELF64 +#if defined(__LIBELF64) #define ELF64_ST_VISIBILITY(o)	((o)&0x3) #endif /* __LIBELF64 */ @@ -521,7 +521,7 @@ typedef struct { Elf32_Sword		r_addend; } Elf32_Rela; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Addr		r_offset; Elf64_Xword		r_info; @@ -541,7 +541,7 @@ typedef struct { #define ELF32_R_TYPE(i)		((unsigned char)(i)) #define ELF32_R_INFO(s,t)	(((s)<<8)+(unsigned char)(t)) -#if __LIBELF64 +#if defined(__LIBELF64) #define ELF64_R_SYM(i)		((Elf64_Xword)(i)>>32) #define ELF64_R_TYPE(i)		((i)&0xffffffffL) #define ELF64_R_INFO(s,t)	(((Elf64_Xword)(s)<<32)+((t)&0xffffffffL)) @@ -556,7 +556,7 @@ typedef struct { Elf32_Word		n_type;		/* descriptor type */ } Elf32_Nhdr; -#if __LIBELF64 +#if defined(__LIBELF64) /* Solaris and GNU use this layout.  Be compatible. */ /* XXX: Latest ELF specs say it's 64-bit!!! */ typedef struct { @@ -587,7 +587,7 @@ typedef struct { Elf32_Word		p_align; } Elf32_Phdr; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Word		p_type; Elf64_Word		p_flags; @@ -654,7 +654,7 @@ typedef struct { } d_un; } Elf32_Dyn; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Sxword	d_tag; union { @@ -798,7 +798,7 @@ typedef struct { Elf32_Half		si_flags; } Elf32_Syminfo; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Half		si_boundto; Elf64_Half		si_flags; @@ -863,7 +863,7 @@ typedef struct { typedef Elf32_Half	Elf32_Versym; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Half		vd_version; @@ -933,7 +933,7 @@ typedef Elf64_Half	Elf64_Versym; /* * Move section */ -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf32_Lword		m_value; @@ -973,7 +973,7 @@ typedef struct { } c_un; } Elf32_Cap; -#if __LIBELF64 +#if defined(__LIBELF64) typedef struct { Elf64_Xword     	c_tag; diff --git a/lib/gelf.h b/lib/gelf.h index 5af0558..98a759c 100644 --- a/lib/gelf.h +++ b/lib/gelf.h @@ -22,15 +22,15 @@ #ifndef _GELF_H #define _GELF_H -#if __LIBELF_INTERNAL__ +#if defined(__LIBELF_INTERNAL__) #include <libelf.h> #else /* __LIBELF_INTERNAL__ */ #include <libelf/libelf.h> #endif /* __LIBELF_INTERNAL__ */ -#if __LIBELF_NEED_LINK_H +#if defined(__LIBELF_NEED_LINK_H) #include <link.h> -#elif __LIBELF_NEED_SYS_LINK_H +#elif defined(__LIBELF_NEED_SYS_LINK_H) #include <sys/link.h> #endif /* __LIBELF_NEED_LINK_H */ @@ -46,7 +46,7 @@ extern "C" { # endif /* __STDC__ || defined(__cplusplus) */ #endif /* __P */ -#if !__LIBELF64 +#if !defined(__LIBELF64) #error "GElf is not supported on this system." @@ -71,7 +71,7 @@ typedef Elf64_Sym	GElf_Sym; /* * Symbol versioning */ -#if __LIBELF_SYMBOL_VERSIONS +#if defined(__LIBELF_SYMBOL_VERSIONS) typedef Elf64_Verdef	GElf_Verdef; typedef Elf64_Verneed	GElf_Verneed; typedef Elf64_Verdaux	GElf_Verdaux; diff --git a/lib/libelf.h b/lib/libelf.h index 3ebd0f3..788482d 100644 --- a/lib/libelf.h +++ b/lib/libelf.h @@ -25,7 +25,7 @@ #include <stddef.h>	/* for size_t */ #include <sys/types.h> -#if __LIBELF_INTERNAL__ +#if defined(__LIBELF_INTERNAL__) #include <sys_elf.h> #else /* __LIBELF_INTERNAL__ */ #include <libelf/sys_elf.h> @@ -224,7 +224,7 @@ extern Elf_Data *elf32_xlatetom __P((Elf_Data *__dst, const Elf_Data *__src, */ extern long elf32_checksum __P((Elf *__elf)); -#if __LIBELF64 +#if defined(__LIBELF64) /* * 64-bit ELF functions * Not available on all platforms diff --git a/lib/sys_elf.h.in b/lib/sys_elf.h.in index b71a20d..722051b 100644 --- a/lib/sys_elf.h.in +++ b/lib/sys_elf.h.in @@ -68,7 +68,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA #ifdef __LIBELF_HEADER_ELF_H # include __LIBELF_HEADER_ELF_H #else /* __LIBELF_HEADER_ELF_H */ -# if __LIBELF_INTERNAL__ +# if defined(__LIBELF_INTERNAL__) #  include <elf_repl.h> # else /* __LIBELF_INTERNAL__ */ #  include <libelf/elf_repl.h> @@ -92,7 +92,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA #  define STN_UNDEF	0 # endif /* STN_UNDEF */ -# if __LIBELF64 +# if defined(__LIBELF64) #  ifndef ELF64_FSZ_ADDR #   define ELF64_FSZ_ADDR	8 @@ -116,7 +116,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA #   define ELF64_R_INFO(s,t)	(((Elf64_Xword)(s)<<32)+((t)&0xffffffffL)) #  endif /* ELF64_R_SYM */ -#  if __LIBELF64_LINUX +#  if defined(__LIBELF64_LINUX) typedef __libelf_u64_t	Elf64_Addr; typedef __libelf_u16_t	Elf64_Half; typedef __libelf_u64_t	Elf64_Off; diff --git a/lib/sys_elf.h.w32 b/lib/sys_elf.h.w32 index 0f93c55..7360104 100644 --- a/lib/sys_elf.h.w32 +++ b/lib/sys_elf.h.w32 @@ -68,7 +68,7 @@ #ifdef __LIBELF_HEADER_ELF_H # include __LIBELF_HEADER_ELF_H #else /* __LIBELF_HEADER_ELF_H */ -# if __LIBELF_INTERNAL__ +# if defined(__LIBELF_INTERNAL__) #  include <elf_repl.h> # else /* __LIBELF_INTERNAL__ */ #  include <libelf/elf_repl.h> @@ -92,7 +92,7 @@ #  define STN_UNDEF	0 # endif /* STN_UNDEF */ -# if __LIBELF64 +# if defined(__LIBELF64) #  ifndef ELF64_FSZ_ADDR #   define ELF64_FSZ_ADDR	8 @@ -116,7 +116,7 @@ #   define ELF64_R_INFO(s,t)	(((Elf64_Xword)(s)<<32)+((t)&0xffffffffL)) #  endif /* ELF64_R_SYM */ -#  if __LIBELF64_LINUX +#  if defined(__LIBELF64_LINUX) typedef __libelf_u64_t	Elf64_Addr; typedef __libelf_u16_t	Elf64_Half; typedef __libelf_u64_t	Elf64_Off; </ins>