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debug/dwarf: support compressed debug sections #11773

Closed qeedquan closed 8 years ago

qeedquan commented 9 years ago

I upgraded to go 1.5 beta2 and get this error when building any cgo libraries cannot load DWARF output from $WORK/command-line-arguments/_obj//cgo.o: decoding dwarf section info at offset 0x0: too short

even simple programs that just does

package main

// #include <stdio.h>
import "C"

func main() {
    C.puts("test")
}

fails to build for me Using gcc 4.9.2 on amd64

alexbrainman commented 9 years ago

What does "go version" output?

Alex

ianlancetaylor commented 9 years ago

What operating system?

Can you show us the output of "go build -x" for a small failing program?

qeedquan commented 9 years ago

go version is "go1.5beta2 linux/amd64"

go build -x test.go (the program above):

WORK=/tmp/go-build438987599
mkdir -p $WORK/command-line-arguments/_obj/
cd /home/qeed
CGO_LDFLAGS="-g" "-O2" ./apps/go/pkg/tool/linux_amd64/cgo -objdir $WORK/command-line-arguments/_obj/ -importpath command-line-arguments -- -I $WORK/command-line-arguments/_obj/ test.go
# command-line-arguments
cannot load DWARF output from $WORK/command-line-arguments/_obj//_cgo_.o: decoding dwarf section info at offset 0x0: too short
ianlancetaylor commented 9 years ago

Thanks. Next step: copy test.go into an empty directory, cd to that directory, and run

CGO_LDFLAGS="-g -O2" go tool cgo -debug-gcc -objdir . -importpath command-line-arguments -- -I . test.go

Please attach the output of that.

Also, do you have GOROOT set in the environment?

qeedquan commented 9 years ago

I have GOROOT set, but I also tried to unset it and ran the program, either way it gives me an error The cgo.o file: http://spark.ofloo.net/~qeed/_cgo_.o

$ gcc -E -dM -xc -m64 -I . - <<EOF
#line 3 "/home/qeed/t/test.go"
 #include <stdio.h>

#include <stddef.h> /* for ptrdiff_t and size_t below */

/* Define intgo when compiling with GCC.  */
typedef ptrdiff_t intgo;

typedef struct { char *p; intgo n; } _GoString_;
typedef struct { char *p; intgo n; intgo c; } _GoBytes_;
_GoString_ GoString(char *p);
_GoString_ GoStringN(char *p, int l);
_GoBytes_ GoBytes(void *p, int n);
char *CString(_GoString_);
void *_CMalloc(size_t);
EOF
#define _IO_CURRENTLY_PUTTING 0x800
#define __DBL_MIN_EXP__ (-1021)
#define _IO_peekc_unlocked(_fp) (_IO_BE ((_fp)->_IO_read_ptr >= (_fp)->_IO_read_end, 0) && __underflow (_fp) == EOF ? EOF : *(unsigned char *) (_fp)->_IO_read_ptr)
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#define __GCC_IEC_559_COMPLEX 2
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#define __flexarr []
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#define __TIME_T_TYPE __SYSCALL_SLONG_TYPE
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#define stderr stderr
#define __GLIBC_PREREQ(maj,min) ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
#define __OFF_T_MATCHES_OFF64_T 1
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#define __stub_putmsg 
#define __WCHAR_MAX__ 2147483647
#define __BLKCNT_T_TYPE __SYSCALL_SLONG_TYPE
#define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 1
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#define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1
#define __DBL_DENORM_MIN__ ((double)4.94065645841246544177e-324L)
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#define __unix__ 1
#define _G_HAVE_ST_BLKSIZE defined (_STATBUF_ST_BLKSIZE)
#define __stub_setlogin 
#define __GCC_ATOMIC_CHAR32_T_LOCK_FREE 2
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#define __attribute_alloc_size__(params) __attribute__ ((__alloc_size__ params))
#define __GNUC_PATCHLEVEL__ 2
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#define _IO_FLAGS2_MMAP 1
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#define __SHRT_MAX__ 32767
#define __LDBL_MAX__ 1.18973149535723176502e+4932L
#define _IOS_BIN 128
#define __fortify_function __extern_always_inline __attribute_artificial__
#define _IO_MAGIC_MASK 0xFFFF0000
#define __UINT_LEAST8_MAX__ 255
#define __GCC_ATOMIC_BOOL_LOCK_FREE 2
#define __UINTMAX_TYPE__ long unsigned int
#define __linux 1
#define __DEC32_EPSILON__ 1E-6DF
#define __stub_sigreturn 
#define _BITS_TYPES_H 1
#define _IO_cleanup_region_end(_Doit) 
#define _IO_DONT_CLOSE 0100000
#define __unix 1
#define __UINT32_MAX__ 4294967295U
#define __UID_T_TYPE __U32_TYPE
#define getc(_fp) _IO_getc (_fp)
#define __SIZE_T 
#define __LDBL_MAX_EXP__ 16384
#define _ATFILE_SOURCE 1
#define _IO_ssize_t __ssize_t
#define __WINT_MIN__ 0U
#define __linux__ 1
#define _IOS_OUTPUT 2
#define _SIZE_T_DEFINED_ 
#define __LDBL_REDIR_NTH(name,proto) name proto __THROW
#define __SCHAR_MAX__ 127
#define __USING_NAMESPACE_STD(name) 
#define _IO_UNIFIED_JUMPTABLES 1
#define __WCHAR_MIN__ (-__WCHAR_MAX__ - 1)
#define __KERNEL_STRICT_NAMES 
#define _IO_stderr ((_IO_FILE*)(&_IO_2_1_stderr_))
#define _IO_ferror_unlocked(__fp) (((__fp)->_flags & _IO_ERR_SEEN) != 0)
#define __INT64_C(c) c ## L
#define __NTH(fct) __attribute__ ((__nothrow__ __LEAF)) fct
#define __DBL_DIG__ 15
#define __GCC_ATOMIC_POINTER_LOCK_FREE 2
#define _POSIX_SOURCE 1
#define __SIZEOF_INT__ 4
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#define _DEFAULT_SOURCE 1
#define __attribute_used__ __attribute__ ((__used__))
#define _STDIO_USES_IOSTREAM 
#define _IO_IN_BACKUP 0x100
#define __USER_LABEL_PREFIX__ 
#define __GLIBC__ 2
#define __END_DECLS 
#define __CONCAT(x,y) x ## y
#define __STDC_HOSTED__ 1
#define __LDBL_HAS_INFINITY__ 1
#define __SLONG32_TYPE int
#define _IO_LINE_BUF 0x200
#define _IOS_NOCREATE 32
#define __GNU_LIBRARY__ 6
#define _G_BUFSIZ 8192
#define __FLT_EPSILON__ 1.19209289550781250000e-7F
#define _IO_EOF_SEEN 0x10
#define TMP_MAX 238328
#define __SSIZE_T_TYPE __SWORD_TYPE
#define __DEV_T_TYPE __UQUAD_TYPE
#define _IO_SKIPWS 01
#define _IO_SCIENTIFIC 04000
#define __LDBL_MIN__ 3.36210314311209350626e-4932L
#define __nonnull(params) __attribute__ ((__nonnull__ params))
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#define __THROW __attribute__ ((__nothrow__ __LEAF))
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#define _T_PTRDIFF 
#define __GNUC__ 4
#define __SYSCALL_ULONG_TYPE __ULONGWORD_TYPE
#define __MMX__ 1
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#define _GCC_WCHAR_T 
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#define __INT_FAST32_MAX__ 9223372036854775807L
#define __DBL_HAS_INFINITY__ 1
#define stdin stdin
#define __USE_XOPEN2K 1
#define __DEC32_MIN_EXP__ (-94)
#define __DADDR_T_TYPE __S32_TYPE
#define __END_NAMESPACE_C99 
#define __FD_SETSIZE 1024
#define __attribute_format_strfmon__(a,b) __attribute__ ((__format__ (__strfmon__, a, b)))
#define _IO_MAGIC 0xFBAD0000
#define __INT_FAST16_TYPE__ long int
#define _SIZE_T_DEFINED 
#define _WCHAR_T_DEFINED_ 
#define __USE_POSIX199506 1
#define _FEATURES_H 1
#define __LDBL_HAS_DENORM__ 1
#define __stub_getmsg 
#define _IO_FIXED 010000
#define __stub_fattach 
#define __DEC128_MAX__ 9.999999999999999999999999999999999E6144DL
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#define _IO_UNBUFFERED 2
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#define __S32_TYPE int
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#define __BEGIN_NAMESPACE_STD 
#define __OFF_T_TYPE __SYSCALL_SLONG_TYPE
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#define _T_WCHAR 
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#define _WCHAR_T 
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#define __stub_bdflush 
#define __U16_TYPE unsigned short int
#define _STDIO_H 1
#define _PTRDIFF_T 
#define __GCC_HAVE_DWARF2_CFI_ASM 1
#define __GXX_ABI_VERSION 1002
#define __FLT_MIN_EXP__ (-125)
#define __extern_always_inline extern __always_inline
#define __PTRDIFF_T 
#define __INT_FAST64_TYPE__ long int
#define _ANSI_STDDEF_H 
#define __DBL_MIN__ ((double)2.22507385850720138309e-308L)
#define __REDIRECT(name,proto,alias) name proto __asm__ (__ASMNAME (#alias))
#define __LP64__ 1
#define _IO_off64_t __off64_t
#define __MODE_T_TYPE __U32_TYPE
#define __LEAF_ATTR __attribute__ ((__leaf__))
#define __DECIMAL_BID_FORMAT__ 1
#define __RLIM64_T_TYPE __UQUAD_TYPE
#define _IOS_ATEND 4
#define _IO_BOOLALPHA 0200000
#define __DEC128_MIN__ 1E-6143DL
#define __REGISTER_PREFIX__ 
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#define _IOS_NOREPLACE 64
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#define _IO_TIED_PUT_GET 0x400
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#define __UINT8_TYPE__ unsigned char
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#define __REDIRECT_LDBL(name,proto,alias) __REDIRECT (name, proto, alias)
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#define _PTRDIFF_T_ 
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#define __INT_WCHAR_T_H 
#define _IO_file_flags _flags
#define __USE_XOPEN2K8 1
#define __STRING(x) #x
#define __GCC_ATOMIC_INT_LOCK_FREE 2
#define _T_PTRDIFF_ 
#define __INO_T_TYPE __SYSCALL_ULONG_TYPE
#define __ssize_t_defined 
#define __GNUC_PREREQ(maj,min) ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
#define _SYS_SIZE_T_H 
#define __FLOAT_WORD_ORDER__ __ORDER_LITTLE_ENDIAN__
#define __FSBLKCNT64_T_TYPE __UQUAD_TYPE
#define _IO_feof_unlocked(__fp) (((__fp)->_flags & _IO_EOF_SEEN) != 0)
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#define __stub_gtty 
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#define __stub_sstk 
#define __wur 
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#define __INT32_C(c) c
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#define __SIZE_TYPE__ long unsigned int
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#define __k8 1
#define __LDBL_REDIR(name,proto) name proto
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#define __GCC_ATOMIC_WCHAR_T_LOCK_FREE 2
#define _IO_IS_FILEBUF 0x2000
#define __SIZEOF_PTRDIFF_T__ 8
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#define __errordecl(name,msg) extern void name (void) __attribute__((__error__ (msg)))
#define __restrict_arr __restrict
#define __attribute_artificial__ __attribute__ ((__artificial__))
#define __USE_MISC 1
#define __UWORD_TYPE unsigned long int
#define __x86_64__ 1
#define _SIZE_T_ 
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#define _IO_iconv_t _G_iconv_t
#define _IO_USER_BUF 1
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#define __FLT_MAX_10_EXP__ 38
#define __LONG_MAX__ 9223372036854775807L
#define __WCHAR_T__ 
#define __DEC128_SUBNORMAL_MIN__ 0.000000000000000000000000000000001E-6143DL
#define __FLT_HAS_INFINITY__ 1
#define _BSD_PTRDIFF_T_ 
#define __UINT_FAST16_TYPE__ long unsigned int
#define __bos0(ptr) __builtin_object_size (ptr, 0)
#define __DEC64_MAX__ 9.999999999999999E384DD
#define NULL ((void *)0)
#define __CHAR16_TYPE__ short unsigned int
#define __PRAGMA_REDEFINE_EXTNAME 1
#define __USING_NAMESPACE_C99(name) 
#define _VA_LIST_DEFINED 
#define __BLKSIZE_T_TYPE __SYSCALL_SLONG_TYPE
#define _IO_size_t size_t
#define __INT_LEAST16_MAX__ 32767
#define __stub_lchmod 
#define __DEC64_MANT_DIG__ 16
#define __INT64_MAX__ 9223372036854775807L
#define __UINT_LEAST32_MAX__ 4294967295U
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#define __INT_LEAST64_TYPE__ long int
#define __INT16_TYPE__ short int
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#define __DEC32_MAX_EXP__ 97
#define __INT_FAST8_MAX__ 127
#define __PMT(args) args
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#define _OLD_STDIO_MAGIC 0xFABC0000
#define linux 1
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#define ____FILE_defined 1
#define _IOLBF 1
#define _IO_UPPERCASE 01000
#define __SSE2__ 1
#define __KEY_T_TYPE __S32_TYPE
#define __WORDSIZE 64
#define __BEGIN_DECLS 
#define __LDBL_MANT_DIG__ 64
#define __DBL_HAS_QUIET_NAN__ 1
#define _IO_BAD_SEEN 0x4000
#define __GNUC_VA_LIST 
#define __SIG_ATOMIC_MIN__ (-__SIG_ATOMIC_MAX__ - 1)
#define __code_model_small__ 1
#define __RLIM_T_TYPE __SYSCALL_ULONG_TYPE
#define FILENAME_MAX 4096
#define __k8__ 1
#define __INTPTR_TYPE__ long int
#define __UINT16_TYPE__ short unsigned int
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#define __CLOCKID_T_TYPE __S32_TYPE
#define __SIZEOF_FLOAT__ 4
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#define __HAVE_COLUMN 
#define __stub_fdetach 
#define __UINTPTR_MAX__ 18446744073709551615UL
#define __DEC64_MIN_EXP__ (-382)
#define __stub_chflags 
#define putc(_ch,_fp) _IO_putc (_ch, _fp)
#define __UQUAD_TYPE unsigned long int
#define __USE_POSIX 1
#define __INT_FAST64_MAX__ 9223372036854775807L
#define __GCC_ATOMIC_TEST_AND_SET_TRUEVAL 1
#define BUFSIZ _IO_BUFSIZ
#define __FLT_DIG__ 6
#define __FSID_T_TYPE struct { int __val[2]; }
#define _WCHAR_T_DECLARED 
#define __UINT_FAST64_TYPE__ long unsigned int
#define _IO_putc_unlocked(_ch,_fp) (_IO_BE ((_fp)->_IO_write_ptr >= (_fp)->_IO_write_end, 0) ? __overflow (_fp, (unsigned char) (_ch)) : (unsigned char) (*(_fp)->_IO_write_ptr++ = (_ch)))
#define __LDBL_REDIR_DECL(name) 
#define __INT_MAX__ 2147483647
#define __amd64__ 1
#define __S16_TYPE short int
#define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
#define _T_SIZE_ 
#define _G_va_list __gnuc_va_list
#define _IOS_INPUT 1
#define __INT64_TYPE__ long int
#define __FLT_MAX_EXP__ 128
#define __ORDER_BIG_ENDIAN__ 4321
#define __ptr_t void *
#define __DBL_MANT_DIG__ 53
#define ___int_size_t_h 
#define __TIMER_T_TYPE void *
#define __INT_LEAST64_MAX__ 9223372036854775807L
#define __GCC_ATOMIC_CHAR16_T_LOCK_FREE 2
#define __GLIBC_MINOR__ 21
#define __DEC64_MIN__ 1E-383DD
#define __WINT_TYPE__ unsigned int
#define __UINT_LEAST32_TYPE__ unsigned int
#define __SIZEOF_SHORT__ 2
#define __SSE__ 1
#define __LDBL_MIN_EXP__ (-16381)
#define _IO_va_list __gnuc_va_list
#define stdout stdout
#define __REDIRECT_NTHNL(name,proto,alias) name proto __asm__ (__ASMNAME (#alias)) __THROWNL
#define EOF (-1)
#define __INT_LEAST8_MAX__ 127
#define __extern_inline extern __inline
#define __USE_POSIX199309 1
#define ____mbstate_t_defined 1
#define __SIZEOF_INT128__ 16
#define __BLKCNT64_T_TYPE __SQUAD_TYPE
#define __LDBL_MAX_10_EXP__ 4932
#define __ATOMIC_RELAXED 0
#define __FSBLKCNT_T_TYPE __SYSCALL_ULONG_TYPE
#define __DBL_EPSILON__ ((double)2.22044604925031308085e-16L)
#define __stub_stty 
#define _SIZET_ 
#define _LP64 1
#define __REDIRECT_NTH_LDBL(name,proto,alias) __REDIRECT_NTH (name, proto, alias)
#define __UINT8_C(c) c
#define __INT_LEAST32_TYPE__ int
#define __wchar_t__ 
#define SEEK_END 2
#define __SIZEOF_WCHAR_T__ 4
#define __USE_POSIX_IMPLICITLY 1
#define __UINT64_TYPE__ long unsigned int
#define __REDIRECT_NTH(name,proto,alias) name proto __asm__ (__ASMNAME (#alias)) __THROW
#define _IO_RIGHT 04
#define __END_NAMESPACE_STD 
#define _STDDEF_H_ 
#define __INT_FAST8_TYPE__ signed char
#define __PID_T_TYPE __S32_TYPE
#define P_tmpdir "/tmp"
#define __attribute_pure__ __attribute__ ((__pure__))
#define __WORDSIZE_TIME64_COMPAT32 1
#define _IO_stdin ((_IO_FILE*)(&_IO_2_1_stdin_))
#define _IO_cleanup_region_start(_fct,_fp) 
#define _IO_NO_READS 4
#define _IO_DEC 020
#define __DBL_DECIMAL_DIG__ 17
#define __FXSR__ 1
#define __DEC_EVAL_METHOD__ 2
#define _SIZE_T 
#define _IO_ERR_SEEN 0x20
#define __ULONG32_TYPE unsigned int
#define _G_config_h 1
#define FOPEN_MAX 16
#define _IO_STDIO 040000
#define __off_t_defined 
#define _IO_IS_APPENDING 0x1000
#define _GCC_SIZE_T 
#define __INO64_T_TYPE __UQUAD_TYPE
#define __UINT32_C(c) c ## U
#define __INTMAX_MAX__ 9223372036854775807L
#define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__
#define __size_t__ 
#define _IO_BUFSIZ _G_BUFSIZ
#define __FLT_DENORM_MIN__ 1.40129846432481707092e-45F
#define __BEGIN_NAMESPACE_C99 
#define __INT8_MAX__ 127
#define __UINT_FAST32_TYPE__ long unsigned int
#define __INO_T_MATCHES_INO64_T 1
#define _IO_fpos_t _G_fpos_t
#define __CHAR32_TYPE__ unsigned int
#define __FLT_MAX__ 3.40282346638528859812e+38F
#define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
#define __INT32_TYPE__ int
#define __SIZEOF_DOUBLE__ 8
#define __FLT_MIN_10_EXP__ (-37)
#define _IO_BE(expr,res) __builtin_expect ((expr), res)
#define __SWORD_TYPE long int
#define __INTMAX_TYPE__ long int
#define __DEC128_MAX_EXP__ 6145
#define _T_SIZE 
#define __va_arg_pack() __builtin_va_arg_pack ()
#define __ATOMIC_CONSUME 1
#define _IO_stdout ((_IO_FILE*)(&_IO_2_1_stdout_))
#define __GNUC_MINOR__ 9
#define __UINTMAX_MAX__ 18446744073709551615UL
#define __DEC32_MANT_DIG__ 7
#define __DBL_MAX_10_EXP__ 308
#define __FILE_defined 1
#define __LDBL_DENORM_MIN__ 3.64519953188247460253e-4951L
#define __INT16_C(c) c
#define __U32_TYPE unsigned int
#define __STDC__ 1
#define __attribute_malloc__ __attribute__ ((__malloc__))
#define __PTRDIFF_TYPE__ long int
#define __attribute_noinline__ __attribute__ ((__noinline__))
#define _IO_HEX 0100
#define __ATOMIC_SEQ_CST 5
#define __CLOCK_T_TYPE __SYSCALL_SLONG_TYPE
#define _IO_fpos64_t _G_fpos64_t
#define __UINT32_TYPE__ unsigned int
#define __UINTPTR_TYPE__ long unsigned int
#define __DEC64_SUBNORMAL_MIN__ 0.000000000000001E-383DD
#define __FSFILCNT64_T_TYPE __UQUAD_TYPE
#define __DEC128_MANT_DIG__ 34
#define __LDBL_MIN_10_EXP__ (-4931)
#define __attribute_deprecated__ __attribute__ ((__deprecated__))
#define _IO_wint_t wint_t
#define __SIZEOF_LONG_LONG__ 8
#define __USE_ATFILE 1
#define _GCC_PTRDIFF_T 
#define __GCC_ATOMIC_LLONG_LOCK_FREE 2
#define __LDBL_DIG__ 18
#define __FLT_DECIMAL_DIG__ 9
#define __UINT_FAST16_MAX__ 18446744073709551615UL
#define __GNUC_GNU_INLINE__ 1
#define ___int_ptrdiff_t_h 
#define __GCC_ATOMIC_SHORT_LOCK_FREE 2
#define _IO_ftrylockfile(_fp) 
#define __glibc_likely(cond) __builtin_expect ((cond), 1)
#define __UINT_FAST8_TYPE__ unsigned char
#define __P(args) args
#define __ATOMIC_ACQ_REL 4
#define __WCHAR_T 
#define __ATOMIC_RELEASE 3
#define _IO_peekc(_fp) _IO_peekc_unlocked (_fp)
$ gcc -w -Wno-error -o./_cgo_.o -gdwarf-2 -c -xc -I . -m64 - <<EOF
#line 3 "/home/qeed/t/test.go"
 #include <stdio.h>

#include <stddef.h> /* for ptrdiff_t and size_t below */

/* Define intgo when compiling with GCC.  */
typedef ptrdiff_t intgo;

typedef struct { char *p; intgo n; } _GoString_;
typedef struct { char *p; intgo n; intgo c; } _GoBytes_;
_GoString_ GoString(char *p);
_GoString_ GoStringN(char *p, int l);
_GoBytes_ GoBytes(void *p, int n);
char *CString(_GoString_);
void *_CMalloc(size_t);
#line 1 "not-declared"
void __cgo_f_1_1(void) { __typeof__(puts) *__cgo_undefined__; }
#line 1 "not-type"
void __cgo_f_1_2(void) { puts *__cgo_undefined__; }
#line 1 "not-const"
void __cgo_f_1_3(void) { enum { __cgo__undefined__ = (puts)*1 }; }
#line 1 "completed"
int __cgo__1 = __cgo__2;
EOF
not-type: In function '__cgo_f_1_2':
not-type:1:32: error: '__cgo_undefined__' undeclared (first use in this function)
not-type:1:32: note: each undeclared identifier is reported only once for each function it appears in
not-const: In function '__cgo_f_1_3':
not-const:1:60: error: invalid operands to binary * (have 'int (*)(const char *)' and 'int')
completed: At top level:
completed:1:16: error: '__cgo__2' undeclared here (not in a function)
$ gcc -w -Wno-error -o./_cgo_.o -gdwarf-2 -c -xc -I . -m64 - <<EOF
#line 3 "/home/qeed/t/test.go"
 #include <stdio.h>

#include <stddef.h> /* for ptrdiff_t and size_t below */

/* Define intgo when compiling with GCC.  */
typedef ptrdiff_t intgo;

typedef struct { char *p; intgo n; } _GoString_;
typedef struct { char *p; intgo n; intgo c; } _GoBytes_;
_GoString_ GoString(char *p);
_GoString_ GoStringN(char *p, int l);
_GoBytes_ GoBytes(void *p, int n);
char *CString(_GoString_);
void *_CMalloc(size_t);
__typeof__(puts) *__cgo__0;
__typeof__(puts) *__cgo__1;
long long __cgodebug_data[] = {
    0,
    0,
    1
};
EOF
cannot load DWARF output from ./_cgo_.o: decoding dwarf section info at offset 0x0: too short
ianlancetaylor commented 9 years ago

You should never set GOROOT in the environment, but I understand that you are saying that this is not the problem here.

Please put this (from the end of the above) into a file x.c:

line 3 "/home/qeed/t/test.go"

include

include /* for ptrdiff_t and size_t below */

/* Define intgo when compiling with GCC. */ typedef ptrdiff_t intgo;

typedef struct { char p; intgo n; } GoString; typedef struct { char p; intgo n; intgo c; } GoBytes; GoString GoString(char p); GoString GoStringN(char p, int l); GoBytes GoBytes(void p, int n); char CString(GoString); void *_CMalloc(size_t); typeof(puts) cgo0; typeof(puts) cgo1; long long __cgodebug_data[] = { 0, 0, 1 };

Then run

gcc -w -Wno-error -o./cgo.o -gdwarf-2 -c -xc -I . -m64 x.c

Then attach the output of

readelf -s --wide ./cgo.o

Thanks.

qeedquan commented 9 years ago

I should also say that 1.5beta1 used to work, so there was a commit between then and now that broke it

Symbol table '.symtab' contains 15 entries: Num: Value Size Type Bind Vis Ndx Name 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS x.c 2: 0000000000000000 0 SECTION LOCAL DEFAULT 1 3: 0000000000000000 0 SECTION LOCAL DEFAULT 2 4: 0000000000000000 0 SECTION LOCAL DEFAULT 3 5: 0000000000000000 0 SECTION LOCAL DEFAULT 4 6: 0000000000000000 0 SECTION LOCAL DEFAULT 6 7: 0000000000000000 0 SECTION LOCAL DEFAULT 7 8: 0000000000000000 0 SECTION LOCAL DEFAULT 9 9: 0000000000000000 0 SECTION LOCAL DEFAULT 10 10: 0000000000000000 0 SECTION LOCAL DEFAULT 12 11: 0000000000000000 0 SECTION LOCAL DEFAULT 11 12: 0000000000000008 8 OBJECT GLOBAL DEFAULT COM cgo0 13: 0000000000000008 8 OBJECT GLOBAL DEFAULT COM cgo1 14: 0000000000000000 24 OBJECT GLOBAL DEFAULT 2 __cgodebug_data

ianlancetaylor commented 9 years ago

My apologies, I wrote the wrong thing. I was looking for

readelf -S --wide ./_cgo.o

(upper case -S, not lower case -s).

It's extremely odd that this changed between beta1 and beta2. I can not see any relevant changes in cmd/cgo, cmd/go, debug/elf, debug/dwarf, and I can't think of any other relevant code.

qeedquan commented 9 years ago

Hm, I have tried reverting back to 1.4.2 and now it gives me the same error, maybe there is something wrong with my gcc install, though I can't think of anything I did recently that could affect it. I tried with CC=clang and it works for me.

I might have to reinstall some packages, but in the mean time let me paste the readelf output readelf -S --wide ./cgo.o 

There are 16 section headers, starting at offset 0x668:

Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            0000000000000000 000000 000000 00      0   0  0
  [ 1] .text             PROGBITS        0000000000000000 000040 000000 00  AX  0   0  1
  [ 2] .data             PROGBITS        0000000000000000 000040 000018 00  WA  0   0 16
  [ 3] .bss              NOBITS          0000000000000000 000058 000000 00  WA  0   0  1
  [ 4] .zdebug_info      PROGBITS        0000000000000000 000058 00007e 00      0   0  1
  [ 5] .rela.zdebug_info RELA            0000000000000000 0003d8 0001e0 18   I 14   4  8
  [ 6] .zdebug_abbrev    PROGBITS        0000000000000000 0000d6 000069 00      0   0  1
  [ 7] .zdebug_aranges   PROGBITS        0000000000000000 00013f 00001f 00      0   0  1
  [ 8] .rela.zdebug_aranges RELA            0000000000000000 0005b8 000018 18   I 14   7  8
  [ 9] .debug_line       PROGBITS        0000000000000000 00015e 000035 00      0   0  1
  [10] .zdebug_str       PROGBITS        0000000000000000 000193 0000a0 01  MS  0   0  1
  [11] .comment          PROGBITS        0000000000000000 000233 000012 01  MS  0   0  1
  [12] .note.GNU-stack   PROGBITS        0000000000000000 000245 000000 00      0   0  1
  [13] .shstrtab         STRTAB          0000000000000000 0005d0 000093 00      0   0  1
  [14] .symtab           SYMTAB          0000000000000000 000248 000168 18     15  12  8
  [15] .strtab           STRTAB          0000000000000000 0003b0 000027 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), l (large)
  I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
  O (extra OS processing required) o (OS specific), p (processor specific)
ianlancetaylor commented 9 years ago

Thanks. Your compiler is emitting compressed debug info. The Go packages don't know how to parse that yet. This is done by the assembler, via the --compress-debug-sections option. Something must have changed to cause that to happen by default.

rsc commented 9 years ago

/cc @aclements

aclements commented 8 years ago

@ianlancetaylor, is there a reference for compressed DWARF? The best I was able to find is a few sentences at https://sourceware.org/gdb/wiki/Internals%20Debugging-File-Formats (which may be sufficient).

I presume the relocations must apply to the decompressed sections, even though the section table technically says they apply to the compressed sections? In that case, I think we have to do this in debug/elf before passing the sections to debug/dwarf, simply because debug/elf handles the relocations.

ianlancetaylor commented 8 years ago

That link is the old way. The new way is the SHF_COMPRESSED flag in an ELF section. Search for SHF_COMPRESSED in http://www.sco.com/developers/gabi/latest/ch4.sheader.html .

As you say, relocation offsets apply to the uncompressed data.

gopherbot commented 8 years ago

CL https://golang.org/cl/17340 mentions this issue.

aclements commented 8 years ago

That link is the old way. The new way is the SHF_COMPRESSED flag in an ELF section. Search for SHF_COMPRESSED in http://www.sco.com/developers/gabi/latest/ch4.sheader.html .

Okay. Is there a flag to ask gcc 4.8.4/as 2.24/ld 2.24 (gold 1.11?) to generate compressed sections so I can test my implementation? Or do I need a newer toolchain?

ianlancetaylor commented 8 years ago

Looks like you need a newer toolchain. In fact, it looks like you need 2.26, which doesn't exist yet. I can send you an object if you like.

aclements commented 8 years ago

In fact, it looks like you need 2.26, which doesn't exist yet.

Oh. :)

I can send you an object if you like.

Please do. Both ELF32 and ELF64 if that's possible.

ianlancetaylor commented 8 years ago

Please do. Both ELF32 and ELF64 if that's possible.

Sent by direct e-mail.

gopherbot commented 8 years ago

CL https://golang.org/cl/17341 mentions this issue.