aboutsummaryrefslogtreecommitdiff
path: root/build2/cxx/guess.cxx
blob: ad5284709b961177c7d64617a7ad41a97f3cbcad (plain)
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
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
// file      : build2/cxx/guess.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#include <build2/cxx/guess>

#include <cstring>  // strlen()

#include <build2/diagnostics>

using namespace std;

namespace build2
{
  namespace cxx
  {
    // Pre-guess the compiler type based on the compiler executable name.
    // Return empty string if can't make a guess (for example, because the
    // compiler name is a generic 'c++'). Note that it only guesses the type,
    // not the variant.
    //
    static string
    pre_guess (const path& cxx)
    {
      tracer trace ("cxx::pre_guess");

      const string s (cxx.leaf ().base ().string ());
      size_t n (s.size ());

      // Name separator characters (e.g., '-' in 'g++-4.8').
      //
      auto sep = [] (char c) -> bool
      {
        return c == '-' || c == '_' || c == '.';
      };

      auto stem = [&sep, &s, n] (const char* x) -> bool
      {
        size_t m (strlen (x));
        size_t p (s.find (x, 0, m));

        return p != string::npos &&
          (p == 0 || sep (s[p - 1])) &&  // Separated at the beginning.
          ((p += m) == n || sep (s[p])); // Separated at the end.
      };

      if (stem ("g++"))
        return "gcc";

      if (stem ("clang++"))
        return "clang";

      if (stem ("icpc"))
        return "icc";

      // Keep this one last since 'cl' is very generic.
      //
      if (stem ("cl"))
        return "msvc";

      // Warn if the user specified a C compiler instead of C++.
      //
      if (stem ("gcc"))
      {
        warn << cxx << " looks like a C compiler" <<
          info << "should it be 'g++' instead of 'gcc'?";
      }
      else if (stem ("clang"))
      {
        warn << cxx << " looks like a C compiler" <<
          info << "should it be 'clang++' instead of 'clang'?";
      }
      else if (stem ("icc"))
      {
        warn << cxx << " looks like a C compiler" <<
          info << "should it be 'icpc' instead of 'icc'?";
      }

      l4 ([&]{trace << "unable to guess compiler type of " << cxx;});
      return "";
    }

    // Guess the compiler type and variant by running it. If the pre argument
    // is not empty, then only "confirm" the pre-guess. Return empty result if
    // unable to guess.
    //
    struct guess_result
    {
      compiler_id id;
      string signature;
      string checksum;

      bool
      empty () const {return id.empty ();}
    };

    static guess_result
    guess (const path& cxx, const string& pre)
    {
      tracer trace ("cxx::guess");

      guess_result r;

      // Start with -v. This will cover gcc and clang.
      //
      // While icc also writes what may seem like something we can use to
      // detect it:
      //
      // icpc version 16.0.2 (gcc version 4.9.0 compatibility)
      //
      // That first word is actually the executable name. So if we rename
      // icpc to foocpc, we will get:
      //
      // foocpc version 16.0.2 (gcc version 4.9.0 compatibility)
      //
      // In fact, if someone renames icpc to g++, there will be no way for
      // us to detect this. Oh, well, their problem.
      //
      if (r.id.empty () && (pre.empty () || pre == "gcc" || pre == "clang"))
      {
        auto f = [] (string& l) -> guess_result
        {
          // The g++ -v output will have a line (currently last) in the form:
          //
          // "gcc version X.Y.Z ..."
          //
          // The "version" word can probably be translated. For example:
          //
          // gcc version 3.4.4
          // gcc version 4.2.1
          // gcc version 4.8.2 (GCC)
          // gcc version 4.8.5 (Ubuntu 4.8.5-2ubuntu1~14.04.1)
          // gcc version 4.9.2 (Ubuntu 4.9.2-0ubuntu1~14.04)
          // gcc version 5.1.0 (Ubuntu 5.1.0-0ubuntu11~14.04.1)
          // gcc version 6.0.0 20160131 (experimental) (GCC)
          //
          if (l.compare (0, 4, "gcc ") == 0)
            return guess_result {{"gcc", ""}, move (l), ""};

          // The Apple clang++ -v output will have a line (currently first)
          // in the form:
          //
          // "Apple (LLVM|clang) version X.Y.Z ..."
          //
          // Apple clang version 3.1 (tags/Apple/clang-318.0.58) (based on LLVM 3.1svn)
          // Apple clang version 4.0 (tags/Apple/clang-421.0.60) (based on LLVM 3.1svn)
          // Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
          // Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
          // Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
          // Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
          // Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
          // Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)
          // Apple LLVM version 7.0.0 (clang-700.0.53)
          // Apple LLVM version 7.0.0 (clang-700.1.76)
          // Apple LLVM version 7.0.2 (clang-700.1.81)
          // Apple LLVM version 7.3.0 (clang-703.0.16.1)
          //
          // Note that the g++ "alias" for clang++ also includes this line
          // but it is (currently) preceded by "Configured with: ...".
          //
          // Check for Apple clang before the vanilla one since the above
          // line also includes "clang".
          //
          if (l.compare (0, 6, "Apple ") == 0 &&
              (l.compare (6, 5, "LLVM ") == 0 ||
               l.compare (6, 6, "clang ") == 0))
            return guess_result {{"clang", "apple"}, move (l), ""};

          // The vanilla clang++ -v output will have a line (currently first)
          // in the form:
          //
          // "[... ]clang version X.Y.Z[-...] ..."
          //
          // The "version" word can probably be translated. For example:
          //
          // FreeBSD clang version 3.4.1 (tags/RELEASE_34/dot1-final 208032) 20140512
          // Ubuntu clang version 3.5.0-4ubuntu2~trusty2 (tags/RELEASE_350/final) (based on LLVM 3.5.0)
          // Ubuntu clang version 3.6.0-2ubuntu1~trusty1 (tags/RELEASE_360/final) (based on LLVM 3.6.0)
          // clang version 3.7.0 (tags/RELEASE_370/final)
          //
          if (l.find ("clang ") != string::npos)
            return guess_result {{"clang", ""}, move (l), ""};

          return guess_result ();
        };

        // The -v output contains other information (such as the compiler
        // build configuration for gcc or the selected gcc installation for
        // clang) which makes sense to include into the compiler checksum. So
        // ask run() to calculate it for every line of the -v ouput.
        //
        sha256 cs;

        // Suppress all the compiler errors because we may be trying an
        // unsupported option.
        //
        r = run<guess_result> (cxx, "-v", f, false, false, &cs);

        if (!r.empty ())
          r.checksum = cs.string ();
      }

      // Next try --version to detect icc.
      //
      if (r.empty () && (pre.empty () || pre == "icc"))
      {
        auto f = [] (string& l) -> guess_result
        {
          // The first line has the " (ICC) " in it, for example:
          //
          // icpc (ICC) 9.0 20060120
          // icpc (ICC) 11.1 20100414
          // icpc (ICC) 12.1.0 20110811
          // icpc (ICC) 14.0.0 20130728
          // icpc (ICC) 15.0.2 20150121
          // icpc (ICC) 16.0.2 20160204
          //
          if (l.find (" (ICC) ") != string::npos)
            return guess_result {{"icc", ""}, move (l), ""};

          return guess_result ();
        };

        r = run<guess_result> (cxx, "--version", f, false);
      }

      // Finally try to run it without any options to detect msvc.
      //
      //
      if (r.empty () && (pre.empty () || pre == "msvc"))
      {
        auto f = [] (string& l) -> guess_result
        {
          // Check for "Microsoft (R)" and "C/C++" in the first line as a
          // signature since all other words/positions can be translated. For
          // example:
          //
          // Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 13.10.6030 for 80x86
          // Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.762 for 80x86
          // Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.30729.01 for 80x86
          // Compilador de optimizacion de C/C++ de Microsoft (R) version 16.00.30319.01 para x64
          // Microsoft (R) C/C++ Optimizing Compiler Version 17.00.50727.1 for x86
          // Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21005.1 for x86
          // Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23026 for x86
          //
          // In the recent versions the architecture is either "x86", "x64",
          // or "ARM".
          //
          if (l.find ("Microsoft (R)") != string::npos &&
              l.find ("C/C++") != string::npos)
            return guess_result {{"msvc", ""}, move (l), ""};

          return guess_result ();
        };

        r = run<guess_result> (cxx, f, false);
      }

      if (!r.empty ())
      {
        if (!pre.empty () && r.id.type != pre)
        {
          l4 ([&]{trace << "compiler type guess mismatch"
                        << ", pre-guessed " << pre
                        << ", determined " << r.id.type;});

          r = guess_result ();
        }
        else
          l5 ([&]{trace << cxx << " is " << r.id << ": '"
                        << r.signature << "'";});
      }
      else
        l4 ([&]{trace << "unable to determine compiler type of " << cxx;});

      return r;
    }

    static compiler_info
    guess_gcc (const path& cxx, const strings* coptions, guess_result&& gr)
    {
      tracer trace ("cxx::guess_gcc");

      // Extract the version. The signature line has the following format
      // though language words can be translated and even rearranged (see
      // examples above).
      //
      // "gcc version A.B.C[ ...]"
      //
      string& s (gr.signature);

      // Scan the string as words and look for one that looks like a version.
      //
      size_t b (0), e (0);
      while (next_word (s, b, e))
      {
        // The third argument to find_first_not_of() is the length of the
        // first argument, not the length of the interval to check. So to
        // limit it to [b, e) we are also going to compare the result to the
        // end of the word position (first space). In fact, we can just check
        // if it is >= e.
        //
        if (s.find_first_not_of ("1234567890.", b, 11) >= e)
          break;
      }

      if (b == e)
        fail << "unable to extract gcc version from '" << s << "'";

      compiler_version v;
      v.string.assign (s, b, string::npos);

      // Split the version into components.
      //
      size_t vb (b), ve (b);
      auto next = [&s, b, e, &vb, &ve] (const char* m) -> uint64_t
      {
        try
        {
          if (next_word (s, e, vb, ve, '.'))
            return stoull (string (s, vb, ve - vb));
        }
        catch (const invalid_argument&) {}
        catch (const out_of_range&) {}

        error << "unable to extract gcc " << m << " version from '"
              << string (s, b, e - b) << "'";
        throw failed ();
      };

      v.major = next ("major");
      v.minor = next ("minor");
      v.patch = next ("patch");

      if (e != s.size ())
        v.build.assign (s, e + 1, string::npos);

      // Figure out the target architecture. This is actually a lot trickier
      // than one would have hoped.
      //
      // There is the -dumpmachine option but gcc doesn't adjust it per the
      // compile options (e.g., -m32). However, starting with 4.6 it has the
      // -print-multiarch option which gives (almost) the right answer. The
      // "almost" part has to do with it not honoring the -arch option (which
      // is really what this compiler is building for). To get to that, we
      // would have to resort to a hack like this:
      //
      // gcc -v -E - 2>&1 | grep cc1
      // .../cc1 ... -mtune=generic -march=x86-64
      //
      // Also, -print-multiarch will print am empty line if the compiler
      // actually wasn't built with multi-arch support.
      //
      // So for now this is what we are going to do for the time being: First
      // try -print-multiarch. If that works out (recent gcc configure with
      // multi-arch support), then use the result. Otherwise, fallback to
      // -dumpmachine (older gcc or not multi-arch).
      //
      cstrings args {cxx.string ().c_str (), "-print-multiarch"};
      if (coptions != nullptr)
        append_options (args, *coptions);
      args.push_back (nullptr);

      // The output of both -print-multiarch and -dumpmachine is a single line
      // containing just the target triplet.
      //
      auto f = [] (string& l) {return move (l);};

      string t (run<string> (args.data (), f, false));

      if (t.empty ())
      {
        l5 ([&]{trace << cxx << " doesn's support -print-multiarch, "
                      << "falling back to -dumpmachine";});

        args[1] = "-dumpmachine";
        t = run<string> (args.data (), f);
      }

      if (t.empty ())
        fail << "unable to extract target architecture from " << cxx
             << " -print-multiarch or -dumpmachine output";

      return compiler_info {
        move (gr.id),
        move (v),
        move (gr.signature),
        move (gr.checksum), // Calculated on whole -v output.
        move (t)};
    }

    static compiler_info
    guess_clang (const path& cxx, const strings* coptions, guess_result&& gr)
    {
      // Extract the version. Here we will try to handle both vanilla and
      // Apple clang since the signature lines are fairly similar. They have
      // the following format though language words can probably be translated
      // and even rearranged (see examples above).
      //
      // "[... ]clang version A.B.C[( |-)...]"
      // "Apple (clang|LLVM) version A.B[.C] ..."
      //
      string& s (gr.signature);

      // Some overrides for testing.
      //
      //s = "clang version 3.7.0 (tags/RELEASE_370/final)";
      //
      //gr.id.variant = "apple";
      //s = "Apple LLVM version 7.3.0 (clang-703.0.16.1)";
      //s = "Apple clang version 3.1 (tags/Apple/clang-318.0.58) (based on LLVM 3.1svn)";

      // Scan the string as words and look for one that looks like a version.
      // Use '-' as a second delimiter to handle versions like
      // "3.6.0-2ubuntu1~trusty1".
      //
      size_t b (0), e (0);
      while (next_word (s, b, e, ' ', '-'))
      {
        // The third argument to find_first_not_of() is the length of the
        // first argument, not the length of the interval to check. So to
        // limit it to [b, e) we are also going to compare the result to the
        // end of the word position (first space). In fact, we can just check
        // if it is >= e.
        //
        if (s.find_first_not_of ("1234567890.", b, 11) >= e)
          break;
      }

      if (b == e)
        fail << "unable to extract clang version from '" << s << "'";

      compiler_version v;
      v.string.assign (s, b, string::npos);

      // Split the version into components.
      //
      size_t vb (b), ve (b);
      auto next = [&s, b, e, &vb, &ve] (const char* m, bool opt) -> uint64_t
      {
        try
        {
          if (next_word (s, e, vb, ve, '.'))
            return stoull (string (s, vb, ve - vb));

          if (opt)
            return 0;
        }
        catch (const invalid_argument&) {}
        catch (const out_of_range&) {}

        error << "unable to extract clang " << m << " version from '"
              << string (s, b, e - b) << "'";
        throw failed ();
      };

      v.major = next ("major", false);
      v.minor = next ("minor", false);
      v.patch = next ("patch", gr.id.variant == "apple");

      if (e != s.size ())
        v.build.assign (s, e + 1, string::npos);

      // Figure out the target architecture.
      //
      // Unlike gcc, clang doesn't have -print-multiarch. Its -dumpmachine,
      // however, respects the compile options (e.g., -m32).
      //
      cstrings args {cxx.string ().c_str (), "-dumpmachine"};
      if (coptions != nullptr)
        append_options (args, *coptions);
      args.push_back (nullptr);

      // The output of -dumpmachine is a single line containing just the
      // target triplet.
      //
      string t (run<string> (args.data (), [] (string& l) {return move (l);}));

      if (t.empty ())
        fail << "unable to extract target architecture from " << cxx
             << " -dumpmachine output";

      return compiler_info {
        move (gr.id),
        move (v),
        move (gr.signature),
        move (gr.checksum), // Calculated on whole -v output.
        move (t)};
    }

    static compiler_info
    guess_icc (const path& cxx, const strings* coptions, guess_result&& gr)
    {
      // Extract the version. If the version has the fourth component, then
      // the signature line (extracted with --version) won't include it. So we
      // will have to get a more elaborate line with -V. We will also have to
      // do it to get the compiler target that respects the -m option: icc
      // doesn't support -print-multiarch like gcc and its -dumpmachine
      // doesn't respect -m like clang. In fact, its -dumpmachine is
      // completely broken as it appears to print the compiler's host and not
      // the target (e.g., .../bin/ia32/icpc prints x86_64-linux-gnu).
      //
      // Some examples of the signature lines from -V output:
      //
      // Intel(R) C++ Compiler for 32-bit applications, Version 9.1 Build 20070215Z Package ID: l_cc_c_9.1.047
      // Intel(R) C++ Compiler for applications running on Intel(R) 64, Version 10.1 Build 20071116
      // Intel(R) C++ Compiler for applications running on IA-32, Version 10.1 Build 20071116 Package ID: l_cc_p_10.1.010
      // Intel C++ Intel 64 Compiler Professional for applications running on Intel 64, Version 11.0 Build 20081105 Package ID: l_cproc_p_11.0.074
      // Intel(R) C++ Intel(R) 64 Compiler Professional for applications running on Intel(R) 64, Version 11.1 Build 20091130 Package ID: l_cproc_p_11.1.064
      // Intel C++ Intel 64 Compiler XE for applications running on Intel 64, Version 12.0.4.191 Build 20110427
      // Intel(R) C++ Intel(R) 64 Compiler for applications running on Intel(R) 64, Version 16.0.2.181 Build 20160204
      // Intel(R) C++ Intel(R) 64 Compiler for applications running on IA-32, Version 16.0.2.181 Build 20160204
      // Intel(R) C++ Intel(R) 64 Compiler for applications running on Intel(R) MIC Architecture, Version 16.0.2.181 Build 20160204
      //
      // We should probably also assume the language words can be translated
      // and even rearranged.
      //
      string& s (gr.signature);
      s.clear ();

      auto f = [] (string& l)
      {
        return l.compare (0, 5, "Intel") == 0 && (l[5] == '(' || l[5] == ' ')
          ? move (l)
          : string ();
      };

      // The -V output is sent to STDERR.
      //
      s = run<string> (cxx, "-V", f, false);

      if (s.empty ())
        fail << "unable to extract signature from " << cxx << " -V output";

      if (s.find ("C++") == string::npos)
        fail << cxx << " does not appear to be the Intel C++ compiler" <<
          info << "extracted signature: '" << s << "'";

      // Scan the string as words and look for the version. It consist of only
      // digits and periods and contains at least one period.
      //

      // Some overrides for testing.
      //
      //s = "Intel(R) C++ Compiler for 32-bit applications, Version 9.1 Build 20070215Z Package ID: l_cc_c_9.1.047";
      //s = "Intel(R) C++ Compiler for applications running on Intel(R) 64, Version 10.1 Build 20071116";
      //s = "Intel(R) C++ Compiler for applications running on IA-32, Version 10.1 Build 20071116 Package ID: l_cc_p_10.1.010";
      //s = "Intel C++ Intel 64 Compiler Professional for applications running on Intel 64, Version 11.0 Build 20081105 Package ID: l_cproc_p_11.0.074";
      //s = "Intel(R) C++ Intel(R) 64 Compiler Professional for applications running on Intel(R) 64, Version 11.1 Build 20091130 Package ID: l_cproc_p_11.1.064";
      //s = "Intel C++ Intel 64 Compiler XE for applications running on Intel 64, Version 12.0.4.191 Build 20110427";

      size_t b (0), e (0), n;
      while (next_word (s, b, e, ' ', ',') != 0)
      {
        // The third argument to find_first_not_of() is the length of the
        // first argument, not the length of the interval to check. So to
        // limit it to [b, e) we are also going to compare the result to the
        // end of the word position (first space). In fact, we can just check
        // if it is >= e. Similar logic for find_first_of() except that we add
        // space to the list of character to make sure we don't go too far.
        //
        if (s.find_first_not_of ("1234567890.", b, 11) >= e &&
            s.find_first_of (". ", b, 2) < e)
          break;
      }

      if (b == e)
        fail << "unable to extract icc version from '" << s << "'";

      compiler_version v;
      v.string.assign (s, b, string::npos);

      // Split the version into components.
      //
      size_t vb (b), ve (b);
      auto next = [&s, b, e, &vb, &ve] (const char* m, bool opt) -> uint64_t
      {
        try
        {
          if (next_word (s, e, vb, ve, '.'))
            return stoull (string (s, vb, ve - vb));

          if (opt)
            return 0;
        }
        catch (const invalid_argument&) {}
        catch (const out_of_range&) {}

        error << "unable to extract icc " << m << " version from '"
              << string (s, b, e - b) << "'";
        throw failed ();
      };

      v.major = next ("major", false);
      v.minor = next ("minor", false);
      v.patch = next ("patch", true);

      if (vb != ve && next_word (s, e, vb, ve, '.'))
        v.build.assign (s, vb, ve - vb);

      if (e != s.size ())
      {
        if (!v.build.empty ())
          v.build += ' ';

        v.build.append (s, e + 1, string::npos);
      }

      // Figure out the target CPU by re-running the compiler with -V and
      // compile options (which may include, e.g., -m32). The output will
      // contain two CPU keywords: the first is the host and the second is the
      // target (hopefully this won't get rearranged by the translation).
      //
      // The CPU keywords (based on the above samples) appear to be:
      //
      // "32-bit"
      // "IA-32"
      // "Intel"    "64"
      // "Intel(R)" "64"
      // "Intel(R)" "MIC"      (-dumpmachine says: x86_64-k1om-linux)
      //
      cstrings args {cxx.string ().c_str (), "-V"};
      if (coptions != nullptr)
        append_options (args, *coptions);
      args.push_back (nullptr);

      // The -V output is sent to STDERR.
      //
      string t (run<string> (args.data (), f, false));

      if (t.empty ())
        fail << "unable to extract target architecture from " << cxx
             << " -V output";

      string arch;
      for (b = e = 0; (n = next_word (t, b, e, ' ', ',')) != 0; )
      {
        if (t.compare (b, n, "Intel(R)", 8) == 0 ||
            t.compare (b, n, "Intel", 5) == 0)
        {
          if ((n = next_word (t, b, e, ' ', ',')) != 0)
          {
            if (t.compare (b, n, "64", 2) == 0)
            {
              arch = "x86_64";
            }
            else if (t.compare (b, n, "MIC", 3) == 0)
            {
              arch = "x86_64"; // Plus "-k1om-linux" from -dumpmachine below.
            }
          }
          else
            break;
        }
        else if (t.compare (b, n, "IA-32", 5) == 0 ||
                 t.compare (b, n, "32-bit", 6) == 0)
        {
          arch = "i386";
        }
      }

      if (arch.empty ())
        fail << "unable to extract icc target architecture from '" << t << "'";

      // So we have the CPU but we still need the rest of the triplet. While
      // icc currently doesn't support cross-compilation (at least on Linux)
      // and we could have just used the build triplet (i.e., the architecture
      // on which we are running), who knows what will happen in the future.
      // So instead we are going to use -dumpmachine and substitute the CPU.
      //
      t = run<string> (cxx, "-dumpmachine", [] (string& l) {return move (l);});

      if (t.empty ())
        fail << "unable to extract target architecture from " << cxx
             << " -dumpmachine output";

      // The first component in the triplet is always CPU.
      //
      size_t p (t.find ('-'));

      if (p == string::npos)
        fail << "unable to parse icc target architecture '" << t << "'";

      arch.append (t, p, string::npos);

      // Use the signature line to generate the checksum.
      //
      sha256 cs (s);

      return compiler_info {
        move (gr.id),
        move (v),
        move (gr.signature),
        cs.string (),
        move (arch)};
    }

    static compiler_info
    guess_msvc (const path&, guess_result&& gr)
    {
      // Extract the version. The signature line has the following format
      // though language words can be translated and even rearranged (see
      // examples above).
      //
      // "Microsoft (R) C/C++ Optimizing Compiler Version A.B.C[.D] for CPU"
      //
      // The CPU keywords (based on the above samples) appear to be:
      //
      // "80x86"
      // "x86"
      // "x64"
      // "ARM"
      //
      string& s (gr.signature);

      // Some overrides for testing.
      //
      //s = "Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.30729.01 for 80x86";
      //s = "Compilador de optimizacion de C/C++ de Microsoft (R) version 16.00.30319.01 para x64";

      // Scan the string as words and look for the version. While doing this
      // also keep an eye on the CPU keywords.
      //
      string arch;
      size_t b (0), e (0);

      auto check_cpu = [&arch, &s, &b, &e] () -> bool
      {
        size_t n (e - b);

        if (s.compare (b, n, "x64", 3) == 0 ||
            s.compare (b, n, "x86", 3) == 0 ||
            s.compare (b, n, "ARM", 3) == 0 ||
            s.compare (b, n, "80x86", 5) == 0)
        {
          arch.assign (s, b, n);
          return true;
        }

        return false;
      };

      while (next_word (s, b, e, ' ', ','))
      {
        // First check for the CPU keywords in case in some language they come
        // before the version.
        //
        if (check_cpu ())
          continue;

        // The third argument to find_first_not_of() is the length of the
        // first argument, not the length of the interval to check. So to
        // limit it to [b, e) we are also going to compare the result to the
        // end of the word position (first space). In fact, we can just check
        // if it is >= e.
        //
        if (s.find_first_not_of ("1234567890.", b, 11) >= e)
          break;
      }

      if (b == e)
        fail << "unable to extract msvc version from '" << s << "'";

      compiler_version v;
      v.string.assign (s, b, e - b);

      // Split the version into components.
      //
      size_t vb (b), ve (b);
      auto next = [&s, b, e, &vb, &ve] (const char* m) -> uint64_t
      {
        try
        {
          if (next_word (s, e, vb, ve, '.'))
            return stoull (string (s, vb, ve - vb));
        }
        catch (const invalid_argument&) {}
        catch (const out_of_range&) {}

        error << "unable to extract msvc " << m << " version from '"
              << string (s, b, e - b) << "'";
        throw failed ();
      };

      v.major = next ("major");
      v.minor = next ("minor");
      v.patch = next ("patch");

      if (next_word (s, e, vb, ve, '.'))
        v.build.assign (s, vb, ve - vb);

      // Continue scanning for the CPU.
      //
      if (e != s.size ())
      {
        while (next_word (s, b, e, ' ', ','))
        {
          if (check_cpu ())
            break;
        }
      }

      if (arch.empty ())
        fail << "unable to extract msvc target architecture from "
             << "'" << s << "'";

      // Now we need to map x86, x64, and ARM to the target triplets. The
      // problem is, there aren't any established ones so we got to invent
      // them ourselves. Based on the discussion in <butl/triplet>, we need
      // something in the CPU-VENDOR-OS-ABI form.
      //
      // The CPU part is fairly straightforward with x86 mapped to 'i386' (or
      // maybe 'i686'), x64 to 'x86_64', and ARM to 'arm' (it could also
      // include the version, e.g., 'amrv8').
      //
      // The (toolchain) VENDOR is also straightforward: 'microsoft'. Why not
      // omit it? Two reasons: firstly, there are other compilers with the
      // otherwise same target, for example Intel C++, and it could be useful
      // to distinguish between them. Secondly, by having all four components
      // we remove any parsing ambiguity.
      //
      // OS-ABI is where things are not as clear cut. The OS part shouldn't
      // probably be just 'windows' since we have Win32 and WinCE. And WinRT.
      // And Universal Windows Platform (UWP). So perhaps the following values
      // for OS: 'win32', 'wince', 'winrt', 'winup'.
      //
      // For 'win32' the ABI part could signal the Microsoft C/C++ runtime by
      // calling it 'msvc'. And seeing that the runtimes are incompatible from
      // version to version, we should probably add the 'X.Y' version at the
      // end (so we essentially mimic the DLL name, e.g, msvcr120.dll).  Some
      // suggested we also encode the runtime type (those /M* options) though
      // I am not sure: the only "redistributable" runtime is multi-threaded
      // release DLL.
      //
      // The ABI part for the other OS values needs thinking. For 'winrt' and
      // 'winup' it probably makes sense to encode the WINAPI_FAMILY macro
      // value (perhaps also with the version). Some of its values:
      //
      // WINAPI_FAMILY_APP        Windows 10
      // WINAPI_FAMILY_PC_APP     Windows 8.1
      // WINAPI_FAMILY_PHONE_APP  Windows Phone 8.1
      //
      // For 'wince' we may also want to add the OS version, e.g., 'wince4.2'.
      //
      // Putting it all together, Visual Studio 2015 will then have the
      // following target triplets:
      //
      // x86  i386-microsoft-win32-msvc14.0
      // x64  x86_64-microsoft-win32-msvc14.0
      // ARM  arm-microsoft-winup-???
      //
      if (arch == "ARM")
        fail << "cl.exe ARM/WinRT/UWP target is not yet supported";
      else
      {
        if (arch == "x64")
          arch = "x86_64-microsoft-win32-msvc";
        else if (arch == "x86" || arch == "80x86")
          arch = "i386-microsoft-win32-msvc";
        else
          assert (false);

        // Mapping of compiler versions to runtime versions:
        //
        // 19.00  140/14.0  VS2015
        // 18.00  120/12.0  VS2013
        // 17.00  110/11.0  VS2012
        // 16.00  110/10.0  VS2010
        // 15.00   90/9.0   VS2008
        // 14.00   80/8.0   VS2005
        // 13.10   71/7.1   VS2003
        //
        /**/ if (v.major == 19 && v.minor == 0)  arch += "14.0";
        else if (v.major == 18 && v.minor == 0)  arch += "12.0";
        else if (v.major == 17 && v.minor == 0)  arch += "11.0";
        else if (v.major == 16 && v.minor == 0)  arch += "10.0";
        else if (v.major == 15 && v.minor == 0)  arch += "9.0";
        else if (v.major == 14 && v.minor == 0)  arch += "8.0";
        else if (v.major == 13 && v.minor == 10) arch += "7.1";
        else fail << "unable to map msvc compiler version '" << v.string
                  << "' to runtime version";
      }

      // Use the signature line to generate the checksum.
      //
      sha256 cs (s);

      return compiler_info {
        move (gr.id),
        move (v),
        move (gr.signature),
        cs.string (),
        move (arch)};
    }

    compiler_info
    guess (const path& cxx, const strings* coptions)
    {
      string pre (pre_guess (cxx));
      guess_result gr;

      // If we could pre-guess the type based on the excutable name, then
      // try the test just for that compiler.
      //
      if (pre.empty ())
      {
        gr = guess (cxx, pre);

        if (gr.empty ())
          warn << cxx << " name looks like " << pre << " but it is not";
      }

      if (gr.empty ())
        gr = guess (cxx, "");

      if (gr.empty ())
        fail << "unable to guess C++ compiler type of " << cxx;

      const compiler_id& id (gr.id);

      if (id.type == "gcc")
      {
        assert (id.variant.empty ());
        return guess_gcc (cxx, coptions, move (gr));
      }
      else if (id.type == "clang")
      {
        assert (id.variant.empty () || id.variant == "apple");
        return guess_clang (cxx, coptions, move (gr));
      }
      else if (id.type == "icc")
      {
        assert (id.variant.empty ());
        return guess_icc (cxx, coptions, move (gr));
      }
      else if (id.type == "msvc")
      {
        assert (id.variant.empty ());
        return guess_msvc (cxx, move (gr));
      }
      else
      {
        assert (false);
        return compiler_info ();
      }
    }
  }
}