Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
# Prefer GNU C11 and C++11 to earlier versions.  -*- coding: utf-8 -*-

# This implementation is taken from GNU Autoconf lib/autoconf/c.m4
# commit 017d5ddd82854911f0119691d91ea8a1438824d6
# dated Sun Apr 3 13:57:17 2016 -0700
# This implementation will be obsolete once we can assume Autoconf 2.70
# or later is installed everywhere a Gnulib program might be developed.


# Copyright (C) 2001-2020 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

# Written by David MacKenzie, with help from
# Akim Demaille, Paul Eggert,
# François Pinard, Karl Berry, Richard Pixley, Ian Lance Taylor,
# Roland McGrath, Noah Friedman, david d zuhn, and many others.


# AC_PROG_CC([COMPILER ...])
# --------------------------
# COMPILER ... is a space separated list of C compilers to search for.
# This just gives the user an opportunity to specify an alternative
# search list for the C compiler.
AC_DEFUN_ONCE([AC_PROG_CC],
[AC_LANG_PUSH(C)dnl
AC_ARG_VAR([CC],     [C compiler command])dnl
AC_ARG_VAR([CFLAGS], [C compiler flags])dnl
_AC_ARG_VAR_LDFLAGS()dnl
_AC_ARG_VAR_LIBS()dnl
_AC_ARG_VAR_CPPFLAGS()dnl
m4_ifval([$1],
      [AC_CHECK_TOOLS(CC, [$1])],
[AC_CHECK_TOOL(CC, gcc)
if test -z "$CC"; then
  dnl Here we want:
  dnl	AC_CHECK_TOOL(CC, cc)
  dnl but without the check for a tool without the prefix.
  dnl Until the check is removed from there, copy the code:
  if test -n "$ac_tool_prefix"; then
    AC_CHECK_PROG(CC, [${ac_tool_prefix}cc], [${ac_tool_prefix}cc])
  fi
fi
if test -z "$CC"; then
  AC_CHECK_PROG(CC, cc, cc, , , /usr/ucb/cc)
fi
if test -z "$CC"; then
  AC_CHECK_TOOLS(CC, cl.exe)
fi
if test -z "$CC"; then
  AC_CHECK_TOOL(CC, clang)
fi
])

test -z "$CC" && AC_MSG_FAILURE([no acceptable C compiler found in \$PATH])

# Provide some information about the compiler.
_AS_ECHO_LOG([checking for _AC_LANG compiler version])
set X $ac_compile
ac_compiler=$[2]
for ac_option in --version -v -V -qversion -version; do
  m4_ifdef([_AC_DO_LIMIT],[_AC_DO_LIMIT],[_AC_DO])([$ac_compiler $ac_option >&AS_MESSAGE_LOG_FD])
done

m4_expand_once([_AC_COMPILER_EXEEXT])[]dnl
m4_expand_once([_AC_COMPILER_OBJEXT])[]dnl
_AC_LANG_COMPILER_GNU
if test $ac_compiler_gnu = yes; then
  GCC=yes
else
  GCC=
fi
_AC_PROG_CC_G
dnl
dnl Set ac_prog_cc_stdc to the supported C version.
dnl Also set the documented variable ac_cv_prog_cc_stdc;
dnl its name was chosen when it was cached, but it is no longer cached.
_AC_PROG_CC_C11([ac_prog_cc_stdc=c11
		 ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c11],
  [_AC_PROG_CC_C99([ac_prog_cc_stdc=c99
		    ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99],
     [_AC_PROG_CC_C89([ac_prog_cc_stdc=c89
		       ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89],
		      [ac_prog_cc_stdc=no
		       ac_cv_prog_cc_stdc=no])])])
dnl
AC_LANG_POP(C)dnl
])# AC_PROG_CC



# AC_PROG_CXX([LIST-OF-COMPILERS])
# --------------------------------
# LIST-OF-COMPILERS is a space separated list of C++ compilers to search
# for (if not specified, a default list is used).  This just gives the
# user an opportunity to specify an alternative search list for the C++
# compiler.
# aCC	HP-UX C++ compiler much better than `CC', so test before.
# FCC   Fujitsu C++ compiler
# KCC	KAI C++ compiler
# RCC	Rational C++
# xlC_r	AIX C Set++ (with support for reentrant code)
# xlC	AIX C Set++
AC_DEFUN([AC_PROG_CXX],
[AC_LANG_PUSH(C++)dnl
AC_ARG_VAR([CXX],      [C++ compiler command])dnl
AC_ARG_VAR([CXXFLAGS], [C++ compiler flags])dnl
_AC_ARG_VAR_LDFLAGS()dnl
_AC_ARG_VAR_LIBS()dnl
_AC_ARG_VAR_CPPFLAGS()dnl
_AC_ARG_VAR_PRECIOUS([CCC])dnl
if test -z "$CXX"; then
  if test -n "$CCC"; then
    CXX=$CCC
  else
    AC_CHECK_TOOLS(CXX,
		   [m4_default([$1],
			       [g++ c++ gpp aCC CC cxx cc++ cl.exe FCC KCC RCC xlC_r xlC clang++])],
		   g++)
  fi
fi
# Provide some information about the compiler.
_AS_ECHO_LOG([checking for _AC_LANG compiler version])
set X $ac_compile
ac_compiler=$[2]
for ac_option in --version -v -V -qversion; do
  m4_ifdef([_AC_DO_LIMIT],[_AC_DO_LIMIT],[_AC_DO])([$ac_compiler $ac_option >&AS_MESSAGE_LOG_FD])
done

m4_expand_once([_AC_COMPILER_EXEEXT])[]dnl
m4_expand_once([_AC_COMPILER_OBJEXT])[]dnl
_AC_LANG_COMPILER_GNU
if test $ac_compiler_gnu = yes; then
  GXX=yes
else
  GXX=
fi
_AC_PROG_CXX_G
_AC_PROG_CXX_CXX11([ac_prog_cxx_stdcxx=cxx11
		    ac_cv_prog_cxx_stdcxx=$ac_cv_prog_cxx_cxx11
		    ac_cv_prog_cxx_cxx98=$ac_cv_prog_cxx_cxx11],
   [_AC_PROG_CXX_CXX98([ac_prog_cxx_stdcxx=cxx98
		        ac_cv_prog_cxx_stdcxx=$ac_cv_prog_cxx_cxx98],
		       [ac_prog_cxx_stdcxx=no
		        ac_cv_prog_cxx_stdcxx=no])])
AC_LANG_POP(C++)dnl
])# AC_PROG_CXX


# _AC_C_STD_TRY(STANDARD, TEST-PROLOGUE, TEST-BODY, OPTION-LIST,
#		ACTION-IF-AVAILABLE, ACTION-IF-UNAVAILABLE)
# --------------------------------------------------------------
# Check whether the C compiler accepts features of STANDARD (e.g `c89', `c99')
# by trying to compile a program of TEST-PROLOGUE and TEST-BODY.  If this fails,
# try again with each compiler option in the space-separated OPTION-LIST; if one
# helps, append it to CC.  If eventually successful, run ACTION-IF-AVAILABLE,
# else ACTION-IF-UNAVAILABLE.
AC_DEFUN([_AC_C_STD_TRY],
[AC_MSG_CHECKING([for $CC option to enable ]m4_translit($1, [c], [C])[ features])
AC_CACHE_VAL(ac_cv_prog_cc_$1,
[ac_cv_prog_cc_$1=no
ac_save_CC=$CC
AC_LANG_CONFTEST([AC_LANG_PROGRAM([$2], [$3])])
for ac_arg in '' $4
do
  CC="$ac_save_CC $ac_arg"
  _AC_COMPILE_IFELSE([], [ac_cv_prog_cc_$1=$ac_arg])
  test "x$ac_cv_prog_cc_$1" != "xno" && break
done
rm -f conftest.$ac_ext
CC=$ac_save_CC
])# AC_CACHE_VAL
ac_prog_cc_stdc_options=
case "x$ac_cv_prog_cc_$1" in
  x)
    AC_MSG_RESULT([none needed]) ;;
  xno)
    AC_MSG_RESULT([unsupported]) ;;
  *)
    ac_prog_cc_stdc_options=" $ac_cv_prog_cc_$1"
    CC=$CC$ac_prog_cc_stdc_options
    AC_MSG_RESULT([$ac_cv_prog_cc_$1]) ;;
esac
AS_IF([test "x$ac_cv_prog_cc_$1" != xno], [$5], [$6])
])# _AC_C_STD_TRY

# _AC_C_C99_TEST_HEADER
# ---------------------
# A C header suitable for testing for C99.
AC_DEFUN([_AC_C_C99_TEST_HEADER],
[[#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <wchar.h>
#include <stdio.h>

// Check varargs macros.  These examples are taken from C99 6.10.3.5.
#define debug(...) fprintf (stderr, __VA_ARGS__)
#define showlist(...) puts (#__VA_ARGS__)
#define report(test,...) ((test) ? puts (#test) : printf (__VA_ARGS__))
static void
test_varargs_macros (void)
{
  int x = 1234;
  int y = 5678;
  debug ("Flag");
  debug ("X = %d\n", x);
  showlist (The first, second, and third items.);
  report (x>y, "x is %d but y is %d", x, y);
}

// Check long long types.
#define BIG64 18446744073709551615ull
#define BIG32 4294967295ul
#define BIG_OK (BIG64 / BIG32 == 4294967297ull && BIG64 % BIG32 == 0)
#if !BIG_OK
  your preprocessor is broken;
#endif
#if BIG_OK
#else
  your preprocessor is broken;
#endif
static long long int bignum = -9223372036854775807LL;
static unsigned long long int ubignum = BIG64;

struct incomplete_array
{
  int datasize;
  double data[];
};

struct named_init {
  int number;
  const wchar_t *name;
  double average;
};

typedef const char *ccp;

static inline int
test_restrict (ccp restrict text)
{
  // See if C++-style comments work.
  // Iterate through items via the restricted pointer.
  // Also check for declarations in for loops.
  for (unsigned int i = 0; *(text+i) != '\0'; ++i)
    continue;
  return 0;
}

// Check varargs and va_copy.
static bool
test_varargs (const char *format, ...)
{
  va_list args;
  va_start (args, format);
  va_list args_copy;
  va_copy (args_copy, args);

  const char *str = "";
  int number = 0;
  float fnumber = 0;

  while (*format)
    {
      switch (*format++)
	{
	case 's': // string
	  str = va_arg (args_copy, const char *);
	  break;
	case 'd': // int
	  number = va_arg (args_copy, int);
	  break;
	case 'f': // float
	  fnumber = va_arg (args_copy, double);
	  break;
	default:
	  break;
	}
    }
  va_end (args_copy);
  va_end (args);

  return *str && number && fnumber;
}]])# _AC_C_C99_TEST_HEADER

# _AC_C_C99_TEST_BODY
# -------------------
# A C body suitable for testing for C99, assuming the corresponding header.
AC_DEFUN([_AC_C_C99_TEST_BODY],
[[
  // Check bool.
  _Bool success = false;

  // Check restrict.
  if (test_restrict ("String literal") == 0)
    success = true;
  char *restrict newvar = "Another string";

  // Check varargs.
  success &= test_varargs ("s, d' f .", "string", 65, 34.234);
  test_varargs_macros ();

  // Check flexible array members.
  struct incomplete_array *ia =
    malloc (sizeof (struct incomplete_array) + (sizeof (double) * 10));
  ia->datasize = 10;
  for (int i = 0; i < ia->datasize; ++i)
    ia->data[i] = i * 1.234;

  // Check named initializers.
  struct named_init ni = {
    .number = 34,
    .name = L"Test wide string",
    .average = 543.34343,
  };

  ni.number = 58;

  int dynamic_array[ni.number];
  dynamic_array[ni.number - 1] = 543;

  // work around unused variable warnings
  return (!success || bignum == 0LL || ubignum == 0uLL || newvar[0] == 'x'
	  || dynamic_array[ni.number - 1] != 543);
]])

# _AC_PROG_CC_C99 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
# ----------------------------------------------------------------
# If the C compiler is not in ISO C99 mode by default, try to add an
# option to output variable CC to make it so.  This macro tries
# various options that select ISO C99 on some system or another.  It
# considers the compiler to be in ISO C99 mode if it handles _Bool,
# // comments, flexible array members, inline, long long int, mixed
# code and declarations, named initialization of structs, restrict,
# va_copy, varargs macros, variable declarations in for loops and
# variable length arrays.
AC_DEFUN([_AC_PROG_CC_C99],
[_AC_C_STD_TRY([c99],
[_AC_C_C99_TEST_HEADER],
[_AC_C_C99_TEST_BODY],
dnl Try
dnl GCC		-std=gnu99 (unused restrictive modes: -std=c99 -std=iso9899:1999)
dnl IBM XL C	-qlanglvl=extc1x (V12.1; does not pass C11 test)
dnl IBM XL C	-qlanglvl=extc99
dnl		(pre-V12.1; unused restrictive mode: -qlanglvl=stdc99)
dnl HP cc	-AC99
dnl Intel ICC	-std=c99, -c99 (deprecated)
dnl IRIX	-c99
dnl Solaris	-D_STDC_C99=
dnl		cc's -xc99 option uses linker magic to define the external
dnl		symbol __xpg4 as if by "int __xpg4 = 1;", which enables C99
dnl		behavior for C library functions.  This is not wanted here,
dnl		because it means that a single module compiled with -xc99
dnl		alters C runtime behavior for the entire program, not for
dnl		just the module.  Instead, define the (private) symbol
dnl		_STDC_C99, which suppresses a bogus failure in <stdbool.h>.
dnl		The resulting compiler passes the test case here, and that's
dnl		good enough.  For more, please see the thread starting at:
dnl            https://lists.gnu.org/r/autoconf/2010-12/msg00059.html
dnl Tru64	-c99
dnl with extended modes being tried first.
[[-std=gnu99 -std=c99 -c99 -AC99 -D_STDC_C99= -qlanglvl=extc1x -qlanglvl=extc99]], [$1], [$2])[]dnl
])# _AC_PROG_CC_C99


# _AC_PROG_CC_C11 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
# ----------------------------------------------------------------
# If the C compiler is not in ISO C11 mode by default, try to add an
# option to output variable CC to make it so.  This macro tries
# various options that select ISO C11 on some system or another.  It
# considers the compiler to be in ISO C11 mode if it handles _Alignas,
# _Alignof, _Noreturn, _Static_assert, UTF-8 string literals,
# duplicate typedefs, and anonymous structures and unions.
AC_DEFUN([_AC_PROG_CC_C11],
[_AC_C_STD_TRY([c11],
[_AC_C_C99_TEST_HEADER[
// Check _Alignas.
char _Alignas (double) aligned_as_double;
char _Alignas (0) no_special_alignment;
extern char aligned_as_int;
char _Alignas (0) _Alignas (int) aligned_as_int;

// Check _Alignof.
enum
{
  int_alignment = _Alignof (int),
  int_array_alignment = _Alignof (int[100]),
  char_alignment = _Alignof (char)
};
_Static_assert (0 < -_Alignof (int), "_Alignof is signed");

// Check _Noreturn.
int _Noreturn does_not_return (void) { for (;;) continue; }

// Check _Static_assert.
struct test_static_assert
{
  int x;
  _Static_assert (sizeof (int) <= sizeof (long int),
                  "_Static_assert does not work in struct");
  long int y;
};

// Check UTF-8 literals.
#define u8 syntax error!
char const utf8_literal[] = u8"happens to be ASCII" "another string";

// Check duplicate typedefs.
typedef long *long_ptr;
typedef long int *long_ptr;
typedef long_ptr long_ptr;

// Anonymous structures and unions -- taken from C11 6.7.2.1 Example 1.
struct anonymous
{
  union {
    struct { int i; int j; };
    struct { int k; long int l; } w;
  };
  int m;
} v1;
]],
[_AC_C_C99_TEST_BODY[
  v1.i = 2;
  v1.w.k = 5;
  _Static_assert ((offsetof (struct anonymous, i)
		   == offsetof (struct anonymous, w.k)),
		  "Anonymous union alignment botch");
]],
dnl Try
dnl GCC		-std=gnu11 (unused restrictive mode: -std=c11)
dnl with extended modes being tried first.
dnl
dnl Do not try -qlanglvl=extc1x, because IBM XL C V12.1 (the latest version as
dnl of September 2012) does not pass the C11 test.  For now, try extc1x when
dnl compiling the C99 test instead, since it enables _Static_assert and
dnl _Noreturn, which is a win.  If -qlanglvl=extc11 or -qlanglvl=extc1x passes
dnl the C11 test in some future version of IBM XL C, we'll add it here,
dnl preferably extc11.
[[-std=gnu11]], [$1], [$2])[]dnl
])# _AC_PROG_CC_C11


# AC_PROG_CC_C89
# --------------
# Do not use AU_ALIAS here and in AC_PROG_CC_C99 and AC_PROG_CC_STDC,
# as that'd be incompatible with how Automake redefines AC_PROG_CC.  See
# <https://lists.gnu.org/r/autoconf/2012-10/msg00048.html>.
AU_DEFUN([AC_PROG_CC_C89],
  [AC_REQUIRE([AC_PROG_CC])],
  [$0 is obsolete; use AC_PROG_CC]
)

# AC_PROG_CC_C99
# --------------
AU_DEFUN([AC_PROG_CC_C99],
  [AC_REQUIRE([AC_PROG_CC])],
  [$0 is obsolete; use AC_PROG_CC]
)

# AC_PROG_CC_STDC
# ---------------
AU_DEFUN([AC_PROG_CC_STDC],
  [AC_REQUIRE([AC_PROG_CC])],
  [$0 is obsolete; use AC_PROG_CC]
)


# AC_C_PROTOTYPES
# ---------------
# Check if the C compiler supports prototypes, included if it needs
# options.
AC_DEFUN([AC_C_PROTOTYPES],
[AC_REQUIRE([AC_PROG_CC])dnl
if test "$ac_prog_cc_stdc" != no; then
  AC_DEFINE(PROTOTYPES, 1,
	    [Define to 1 if the C compiler supports function prototypes.])
  AC_DEFINE(__PROTOTYPES, 1,
	    [Define like PROTOTYPES; this can be used by system headers.])
fi
])# AC_C_PROTOTYPES


# _AC_CXX_STD_TRY(STANDARD, TEST-PROLOGUE, TEST-BODY, OPTION-LIST,
#		  ACTION-IF-AVAILABLE, ACTION-IF-UNAVAILABLE)
# ----------------------------------------------------------------
# Check whether the C++ compiler accepts features of STANDARD (e.g
# `cxx98', `cxx11') by trying to compile a program of TEST-PROLOGUE
# and TEST-BODY.  If this fails, try again with each compiler option
# in the space-separated OPTION-LIST; if one helps, append it to CXX.
# If eventually successful, run ACTION-IF-AVAILABLE, else
# ACTION-IF-UNAVAILABLE.
AC_DEFUN([_AC_CXX_STD_TRY],
[AC_MSG_CHECKING([for $CXX option to enable ]m4_translit(m4_translit($1, [x], [+]), [a-z], [A-Z])[ features])
AC_LANG_PUSH(C++)dnl
AC_CACHE_VAL(ac_cv_prog_cxx_$1,
[ac_cv_prog_cxx_$1=no
ac_save_CXX=$CXX
AC_LANG_CONFTEST([AC_LANG_PROGRAM([$2], [$3])])
for ac_arg in '' $4
do
  CXX="$ac_save_CXX $ac_arg"
  _AC_COMPILE_IFELSE([], [ac_cv_prog_cxx_$1=$ac_arg])
  test "x$ac_cv_prog_cxx_$1" != "xno" && break
done
rm -f conftest.$ac_ext
CXX=$ac_save_CXX
])# AC_CACHE_VAL
ac_prog_cxx_stdcxx_options=
case "x$ac_cv_prog_cxx_$1" in
  x)
    AC_MSG_RESULT([none needed]) ;;
  xno)
    AC_MSG_RESULT([unsupported]) ;;
  *)
    ac_prog_cxx_stdcxx_options=" $ac_cv_prog_cxx_$1"
    CXX=$CXX$ac_prog_cxx_stdcxx_options
    AC_MSG_RESULT([$ac_cv_prog_cxx_$1]) ;;
esac
AC_LANG_POP(C++)dnl
AS_IF([test "x$ac_cv_prog_cxx_$1" != xno], [$5], [$6])
])# _AC_CXX_STD_TRY

# _AC_CXX_CXX98_TEST_HEADER
# -------------------------
# A C++ header suitable for testing for CXX98.
AC_DEFUN([_AC_CXX_CXX98_TEST_HEADER],
[[
#include <algorithm>
#include <cstdlib>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <set>
#include <sstream>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

namespace test {
  typedef std::vector<std::string> string_vec;
  typedef std::pair<int,bool> map_value;
  typedef std::map<std::string,map_value> map_type;
  typedef std::set<int> set_type;

  template<typename T>
  class printer {
  public:
    printer(std::ostringstream& os): os(os) {}
    void operator() (T elem) { os << elem << std::endl; }
  private:
    std::ostringstream& os;
  };
}
]])# _AC_CXX_CXX98_TEST_HEADER

# _AC_CXX_CXX98_TEST_BODY
# -----------------------
# A C++ body suitable for testing for CXX98, assuming the corresponding header.
AC_DEFUN([_AC_CXX_CXX98_TEST_BODY],
[[

try {
  // Basic string.
  std::string teststr("ASCII text");
  teststr += " string";

  // Simple vector.
  test::string_vec testvec;
  testvec.push_back(teststr);
  testvec.push_back("foo");
  testvec.push_back("bar");
  if (testvec.size() != 3) {
    throw std::runtime_error("vector size is not 1");
  }

  // Dump vector into stringstream and obtain string.
  std::ostringstream os;
  for (test::string_vec::const_iterator i = testvec.begin();
       i != testvec.end(); ++i) {
    if (i + 1 != testvec.end()) {
      os << teststr << '\n';
    }
  }
  // Check algorithms work.
  std::for_each(testvec.begin(), testvec.end(), test::printer<std::string>(os));
  std::string os_out = os.str();

  // Test pair and map.
  test::map_type testmap;
  testmap.insert(std::make_pair(std::string("key"),
                                std::make_pair(53,false)));

  // Test set.
  int values[] = {9, 7, 13, 15, 4, 18, 12, 10, 5, 3, 14, 19, 17, 8, 6, 20, 16, 2, 11, 1};
  test::set_type testset(values, values + sizeof(values)/sizeof(values[0]));
  std::list<int> testlist(testset.begin(), testset.end());
  std::copy(testset.begin(), testset.end(), std::back_inserter(testlist));
} catch (const std::exception& e) {
  std::cerr << "Caught exception: " << e.what() << std::endl;

  // Test fstream
  std::ofstream of("test.txt");
  of << "Test ASCII text\n" << std::flush;
  of << "N= " << std::hex << std::setw(8) << std::left << 534 << std::endl;
  of.close();
}
std::exit(0);
]])

# _AC_CXX_CXX11_TEST_HEADER
# -------------------------
# A C++ header suitable for testing for CXX11.
AC_DEFUN([_AC_CXX_CXX11_TEST_HEADER],
[[
#include <deque>
#include <functional>
#include <memory>
#include <tuple>
#include <array>
#include <regex>
#include <iostream>

namespace cxx11test
{
  typedef std::shared_ptr<std::string> sptr;
  typedef std::weak_ptr<std::string> wptr;

  typedef std::tuple<std::string,int,double> tp;
  typedef std::array<int, 20> int_array;

  constexpr int get_val() { return 20; }

  struct testinit
  {
    int i;
    double d;
  };

  class delegate  {
  public:
    delegate(int n) : n(n) {}
    delegate(): delegate(2354) {}

    virtual int getval() { return this->n; };
  protected:
    int n;
  };

  class overridden : public delegate {
  public:
    overridden(int n): delegate(n) {}
    virtual int getval() override final { return this->n * 2; }
  };

  class nocopy {
  public:
    nocopy(int i): i(i) {}
    nocopy() = default;
    nocopy(const nocopy&) = delete;
    nocopy & operator=(const nocopy&) = delete;
  private:
    int i;
  };
}
]])# _AC_CXX_CXX11_TEST_HEADER

# _AC_CXX_CXX11_TEST_BODY
# -----------------------
# A C++ body suitable for testing for CXX11, assuming the corresponding header.
AC_DEFUN([_AC_CXX_CXX11_TEST_BODY],
[[
{
  // Test auto and decltype
  std::deque<int> d;
  d.push_front(43);
  d.push_front(484);
  d.push_front(3);
  d.push_front(844);
  int total = 0;
  for (auto i = d.begin(); i != d.end(); ++i) { total += *i; }

  auto a1 = 6538;
  auto a2 = 48573953.4;
  auto a3 = "String literal";

  decltype(a2) a4 = 34895.034;
}
{
  // Test constexpr
  short sa[cxx11test::get_val()] = { 0 };
}
{
  // Test initializer lists
  cxx11test::testinit il = { 4323, 435234.23544 };
}
{
  // Test range-based for and lambda
  cxx11test::int_array array = {9, 7, 13, 15, 4, 18, 12, 10, 5, 3, 14, 19, 17, 8, 6, 20, 16, 2, 11, 1};
  for (int &x : array) { x += 23; }
  std::for_each(array.begin(), array.end(), [](int v1){ std::cout << v1; });
}
{
  using cxx11test::sptr;
  using cxx11test::wptr;

  sptr sp(new std::string("ASCII string"));
  wptr wp(sp);
  sptr sp2(wp);
}
{
  cxx11test::tp tuple("test", 54, 45.53434);
  double d = std::get<2>(tuple);
  std::string s;
  int i;
  std::tie(s,i,d) = tuple;
}
{
  static std::regex filename_regex("^_?([a-z0-9_.]+-)+[a-z0-9]+$");
  std::string testmatch("Test if this string matches");
  bool match = std::regex_search(testmatch, filename_regex);
}
{
  cxx11test::int_array array = {9, 7, 13, 15, 4, 18, 12, 10, 5, 3, 14, 19, 17, 8, 6, 20, 16, 2, 11, 1};
  cxx11test::int_array::size_type size = array.size();
}
{
  // Test constructor delegation
  cxx11test::delegate d1;
  cxx11test::delegate d2();
  cxx11test::delegate d3(45);
}
{
  // Test override and final
  cxx11test::overridden o1(55464);
}
{
  // Test nullptr
  char *c = nullptr;
}
{
  // Test template brackets
  std::vector<std::pair<int,char*>> v1;
}
{
  // Unicode literals
  char const *utf8 = u8"UTF-8 string \u2500";
  char16_t const *utf16 = u"UTF-8 string \u2500";
  char32_t const *utf32 = U"UTF-32 string \u2500";
}
]])

# _AC_PROG_CXX_CXX98 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
# -------------------------------------------------------------------

# If the C++ compiler is not in ISO C++98 mode by default, try to add
# an option to output variable CXX to make it so.  This macro tries
# various options that select ISO C++98 on some system or another.  It
# considers the compiler to be in ISO C++98 mode if it handles basic
# features of the std namespace including: string, containers (list,
# map, set, vector), streams (fstreams, iostreams, stringstreams,
# iomanip), pair, exceptions and algorithms.


AC_DEFUN([_AC_PROG_CXX_CXX98],
[_AC_CXX_STD_TRY([cxx98],
[_AC_CXX_CXX98_TEST_HEADER],
[_AC_CXX_CXX98_TEST_BODY],
dnl Try
dnl GCC		-std=gnu++98 (unused restrictive mode: -std=c++98)
dnl IBM XL C	-qlanglvl=extended
dnl HP aC++	-AA
dnl Intel ICC	-std=gnu++98
dnl Solaris	N/A (default)
dnl Tru64	N/A (default, but -std gnu could be used)
dnl with extended modes being tried first.
[[-std=gnu++98 -std=c++98 -qlanglvl=extended -AA]], [$1], [$2])[]dnl
])# _AC_PROG_CXX_CXX98

# _AC_PROG_CXX_CXX11 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
# -------------------------------------------------------------------
# If the C++ compiler is not in ISO CXX11 mode by default, try to add
# an option to output variable CXX to make it so.  This macro tries
# various options that select ISO C++11 on some system or another.  It
# considers the compiler to be in ISO C++11 mode if it handles all the
# tests from the C++98 checks, plus the following: Language features
# (auto, constexpr, decltype, default/deleted constructors, delegate
# constructors, final, initializer lists, lambda functions, nullptr,
# override, range-based for loops, template brackets without spaces,
# unicode literals) and library features (array, memory (shared_ptr,
# weak_ptr), regex and tuple types).
AC_DEFUN([_AC_PROG_CXX_CXX11],
[_AC_CXX_STD_TRY([cxx11],
[_AC_CXX_CXX11_TEST_HEADER
_AC_CXX_CXX98_TEST_HEADER],
[_AC_CXX_CXX11_TEST_BODY
_AC_CXX_CXX98_TEST_BODY],
dnl Try
dnl GCC		-std=gnu++11 (unused restrictive mode: -std=c++11) [and 0x variants]
dnl IBM XL C	-qlanglvl=extended0x
dnl		(pre-V12.1; unused restrictive mode: -qlanglvl=stdcxx11)
dnl HP aC++	-AA
dnl Intel ICC	-std=c++11 -std=c++0x
dnl Solaris	N/A (no support)
dnl Tru64	N/A (no support)
dnl with extended modes being tried first.
[[-std=gnu++11 -std=c++11 -std=gnu++0x -std=c++0x -qlanglvl=extended0x -AA]], [$1], [$2])[]dnl
])# _AC_PROG_CXX_CXX11