autosetup/cc.tcl

   1 # Copyright (c) 2010 WorkWare Systems http://www.workware.net.au/
   2 # All rights reserved
   3
   4 # @synopsis:
   5 #
   6 # The 'cc' module supports checking various 'features' of the C or C++
   7 # compiler/linker environment. Common commands are 'cc-check-includes',
   8 # 'cc-check-types', 'cc-check-functions', 'cc-with', 'make-config-header' and 'make-template'.
   9 #
  10 # The following environment variables are used if set:
  11 #
  12 ## CC       - C compiler
  13 ## CXX      - C++ compiler
  14 ## CCACHE   - Set to "none" to disable automatic use of ccache
  15 ## CFLAGS   - Additional C compiler flags
  16 ## CXXFLAGS - Additional C++ compiler flags
  17 ## LDFLAGS  - Additional compiler flags during linking
  18 ## LIBS     - Additional libraries to use (for all tests)
  19 ## CROSS    - Tool prefix for cross compilation
  20 #
  21 # The following variables are defined from the corresponding
  22 # environment variables if set.
  23 #
  24 ## CPPFLAGS
  25 ## LINKFLAGS
  26 ## CC_FOR_BUILD
  27 ## LD
  28
  29 use system
  30
  31 module-options {}
  32
  33 # Note that the return code is not meaningful
  34 proc cc-check-something {name code} {
  35         uplevel 1 $code
  36 }
  37
  38 # Checks for the existence of the given function by linking
  39 #
  40 proc cctest_function {function} {
  41         cctest -link 1 -declare "extern void $function\(void);" -code "$function\();"
  42 }
  43
  44 # Checks for the existence of the given type by compiling
  45 proc cctest_type {type} {
  46         cctest -code "$type _x;"
  47 }
  48
  49 # Checks for the existence of the given type/structure member.
  50 # e.g. "struct stat.st_mtime"
  51 proc cctest_member {struct_member} {
  52         # split at the first dot
  53         regexp {^([^.]+)[.](.*)$} $struct_member -> struct member
  54         cctest -code "static $struct _s; return sizeof(_s.$member);"
  55 }
  56
  57 # Checks for the existence of the given define by compiling
  58 #
  59 proc cctest_define {name} {
  60         cctest -code "#ifndef $name\n#error not defined\n#endif"
  61 }
  62
  63 # Checks for the existence of the given name either as
  64 # a macro (#define) or an rvalue (such as an enum)
  65 #
  66 proc cctest_decl {name} {
  67         cctest -code "#ifndef $name\n(void)$name;\n#endif"
  68 }
  69
  70 # @cc-check-sizeof type ...
  71 #
  72 # Checks the size of the given types (between 1 and 32, inclusive).
  73 # Defines a variable with the size determined, or 'unknown' otherwise.
  74 # e.g. for type 'long long', defines 'SIZEOF_LONG_LONG'.
  75 # Returns the size of the last type.
  76 #
  77 proc cc-check-sizeof {args} {
  78         foreach type $args {
  79                 msg-checking "Checking for sizeof $type..."
  80                 set size unknown
  81                 # Try the most common sizes first
  82                 foreach i {4 8 1 2 16 32} {
  83                         if {[cctest -code "static int _x\[sizeof($type) == $i ? 1 : -1\] = { 1 };"]} {
  84                                 set size $i
  85                                 break
  86                         }
  87                 }
  88                 msg-result $size
  89                 set define [feature-define-name $type SIZEOF_]
  90                 define $define $size
  91         }
  92         # Return the last result
  93         get-define $define
  94 }
  95
  96 # Checks for each feature in $list by using the given script.
  97 #
  98 # When the script is evaluated, $each is set to the feature
  99 # being checked, and $extra is set to any additional cctest args.
 100 #
 101 # Returns 1 if all features were found, or 0 otherwise.
 102 proc cc-check-some-feature {list script} {
 103         set ret 1
 104         foreach each $list {
 105                 if {![check-feature $each $script]} {
 106                         set ret 0
 107                 }
 108         }
 109         return $ret
 110 }
 111
 112 # @cc-check-includes includes ...
 113 #
 114 # Checks that the given include files can be used.
 115 proc cc-check-includes {args} {
 116         cc-check-some-feature $args {
 117                 set with {}
 118                 if {[dict exists $::autosetup(cc-include-deps) $each]} {
 119                         set deps [dict keys [dict get $::autosetup(cc-include-deps) $each]]
 120                         msg-quiet cc-check-includes {*}$deps
 121                         foreach i $deps {
 122                                 if {[have-feature $i]} {
 123                                         lappend with $i
 124                                 }
 125                         }
 126                 }
 127                 if {[llength $with]} {
 128                         cc-with [list -includes $with] {
 129                                 cctest -includes $each
 130                         }
 131                 } else {
 132                         cctest -includes $each
 133                 }
 134         }
 135 }
 136
 137 # @cc-include-needs include required ...
 138 #
 139 # Ensures that when checking for '$include', a check is first
 140 # made for each '$required' file, and if found, it is included with '#include'.
 141 proc cc-include-needs {file args} {
 142         foreach depfile $args {
 143                 dict set ::autosetup(cc-include-deps) $file $depfile 1
 144         }
 145 }
 146
 147 # @cc-check-types type ...
 148 #
 149 # Checks that the types exist.
 150 proc cc-check-types {args} {
 151         cc-check-some-feature $args {
 152                 cctest_type $each
 153         }
 154 }
 155
 156 # @cc-check-defines define ...
 157 #
 158 # Checks that the given preprocessor symbol is defined.
 159 proc cc-check-defines {args} {
 160         cc-check-some-feature $args {
 161                 cctest_define $each
 162         }
 163 }
 164
 165 # @cc-check-decls name ...
 166 #
 167 # Checks that each given name is either a preprocessor symbol or rvalue
 168 # such as an enum. Note that the define used is 'HAVE_DECL_xxx'
 169 # rather than 'HAVE_xxx'.
 170 proc cc-check-decls {args} {
 171         set ret 1
 172         foreach name $args {
 173                 msg-checking "Checking for $name..."
 174                 set r [cctest_decl $name]
 175                 define-feature "decl $name" $r
 176                 if {$r} {
 177                         msg-result "ok"
 178                 } else {
 179                         msg-result "not found"
 180                         set ret 0
 181                 }
 182         }
 183         return $ret
 184 }
 185
 186 # @cc-check-functions function ...
 187 #
 188 # Checks that the given functions exist (can be linked).
 189 proc cc-check-functions {args} {
 190         cc-check-some-feature $args {
 191                 cctest_function $each
 192         }
 193 }
 194
 195 # @cc-check-members type.member ...
 196 #
 197 # Checks that the given type/structure members exist.
 198 # A structure member is of the form 'struct stat.st_mtime'.
 199 proc cc-check-members {args} {
 200         cc-check-some-feature $args {
 201                 cctest_member $each
 202         }
 203 }
 204
 205 # @cc-check-function-in-lib function libs ?otherlibs?
 206 #
 207 # Checks that the given function can be found in one of the libs.
 208 #
 209 # First checks for no library required, then checks each of the libraries
 210 # in turn.
 211 #
 212 # If the function is found, the feature is defined and 'lib_$function' is defined
 213 # to '-l$lib' where the function was found, or "" if no library required.
 214 # In addition, '-l$lib' is prepended to the 'LIBS' define.
 215 #
 216 # If additional libraries may be needed for linking, they should be specified
 217 # with '$extralibs' as '-lotherlib1 -lotherlib2'.
 218 # These libraries are not automatically added to 'LIBS'.
 219 #
 220 # Returns 1 if found or 0 if not.
 221 #
 222 proc cc-check-function-in-lib {function libs {otherlibs {}}} {
 223         msg-checking "Checking libs for $function..."
 224         set found 0
 225         cc-with [list -libs $otherlibs] {
 226                 if {[cctest_function $function]} {
 227                         msg-result "none needed"
 228                         define lib_$function ""
 229                         incr found
 230                 } else {
 231                         foreach lib $libs {
 232                                 cc-with [list -libs -l$lib] {
 233                                         if {[cctest_function $function]} {
 234                                                 msg-result -l$lib
 235                                                 define lib_$function -l$lib
 236                                                 # prepend to LIBS
 237                                                 define LIBS "-l$lib [get-define LIBS]"
 238                                                 incr found
 239                                                 break
 240                                         }
 241                                 }
 242                         }
 243                 }
 244         }
 245         if {$found} {
 246                 define [feature-define-name $function]
 247         } else {
 248                 msg-result "no"
 249         }
 250         return $found
 251 }
 252
 253 # @cc-check-tools tool ...
 254 #
 255 # Checks for existence of the given compiler tools, taking
 256 # into account any cross compilation prefix.
 257 #
 258 # For example, when checking for 'ar', first 'AR' is checked on the command
 259 # line and then in the environment. If not found, '${host}-ar' or
 260 # simply 'ar' is assumed depending upon whether cross compiling.
 261 # The path is searched for this executable, and if found 'AR' is defined
 262 # to the executable name.
 263 # Note that even when cross compiling, the simple 'ar' is used as a fallback,
 264 # but a warning is generated. This is necessary for some toolchains.
 265 #
 266 # It is an error if the executable is not found.
 267 #
 268 proc cc-check-tools {args} {
 269         foreach tool $args {
 270                 set TOOL [string toupper $tool]
 271                 set exe [get-env $TOOL [get-define cross]$tool]
 272                 if {[find-executable {*}$exe]} {
 273                         define $TOOL $exe
 274                         continue
 275                 }
 276                 if {[find-executable {*}$tool]} {
 277                         msg-result "Warning: Failed to find $exe, falling back to $tool which may be incorrect"
 278                         define $TOOL $tool
 279                         continue
 280                 }
 281                 user-error "Failed to find $exe"
 282         }
 283 }
 284
 285 # @cc-check-progs prog ...
 286 #
 287 # Checks for existence of the given executables on the path.
 288 #
 289 # For example, when checking for 'grep', the path is searched for
 290 # the executable, 'grep', and if found 'GREP' is defined as 'grep'.
 291 #
 292 # If the executable is not found, the variable is defined as 'false'.
 293 # Returns 1 if all programs were found, or 0 otherwise.
 294 #
 295 proc cc-check-progs {args} {
 296         set failed 0
 297         foreach prog $args {
 298                 set PROG [string toupper $prog]
 299                 msg-checking "Checking for $prog..."
 300                 if {![find-executable $prog]} {
 301                         msg-result no
 302                         define $PROG false
 303                         incr failed
 304                 } else {
 305                         msg-result ok
 306                         define $PROG $prog
 307                 }
 308         }
 309         expr {!$failed}
 310 }
 311
 312 # Adds the given settings to $::autosetup(ccsettings) and
 313 # returns the old settings.
 314 #
 315 proc cc-add-settings {settings} {
 316         if {[llength $settings] % 2} {
 317                 autosetup-error "settings list is missing a value: $settings"
 318         }
 319
 320         set prev [cc-get-settings]
 321         # workaround a bug in some versions of jimsh by forcing
 322         # conversion of $prev to a list
 323         llength $prev
 324
 325         array set new $prev
 326
 327         foreach {name value} $settings {
 328                 switch -exact -- $name {
 329                         -cflags - -includes {
 330                                 # These are given as lists
 331                                 lappend new($name) {*}$value
 332                         }
 333                         -declare {
 334                                 lappend new($name) $value
 335                         }
 336                         -libs {
 337                                 # Note that new libraries are added before previous libraries
 338                                 set new($name) [list {*}$value {*}$new($name)]
 339                         }
 340                         -link - -lang - -nooutput {
 341                                 set new($name) $value
 342                         }
 343                         -source - -sourcefile - -code {
 344                                 # XXX: These probably are only valid directly from cctest
 345                                 set new($name) $value
 346                         }
 347                         default {
 348                                 autosetup-error "unknown cctest setting: $name"
 349                         }
 350                 }
 351         }
 352
 353         cc-store-settings [array get new]
 354
 355         return $prev
 356 }
 357
 358 proc cc-store-settings {new} {
 359         set ::autosetup(ccsettings) $new
 360 }
 361
 362 proc cc-get-settings {} {
 363         return $::autosetup(ccsettings)
 364 }
 365
 366 # Similar to cc-add-settings, but each given setting
 367 # simply replaces the existing value.
 368 #
 369 # Returns the previous settings
 370 proc cc-update-settings {args} {
 371         set prev [cc-get-settings]
 372         cc-store-settings [dict merge $prev $args]
 373         return $prev
 374 }
 375
 376 # @cc-with settings ?{ script }?
 377 #
 378 # Sets the given 'cctest' settings and then runs the tests in '$script'.
 379 # Note that settings such as '-lang' replace the current setting, while
 380 # those such as '-includes' are appended to the existing setting.
 381 #
 382 # If no script is given, the settings become the default for the remainder
 383 # of the 'auto.def' file.
 384 #
 385 ## cc-with {-lang c++} {
 386 ##   # This will check with the C++ compiler
 387 ##   cc-check-types bool
 388 ##   cc-with {-includes signal.h} {
 389 ##     # This will check with the C++ compiler, signal.h and any existing includes.
 390 ##     ...
 391 ##   }
 392 ##   # back to just the C++ compiler
 393 ## }
 394 #
 395 # The '-libs' setting is special in that newer values are added *before* earlier ones.
 396 #
 397 ## cc-with {-libs {-lc -lm}} {
 398 ##   cc-with {-libs -ldl} {
 399 ##     cctest -libs -lsocket ...
 400 ##     # libs will be in this order: -lsocket -ldl -lc -lm
 401 ##   }
 402 ## }
 403 proc cc-with {settings args} {
 404         if {[llength $args] == 0} {
 405                 cc-add-settings $settings
 406         } elseif {[llength $args] > 1} {
 407                 autosetup-error "usage: cc-with settings ?script?"
 408         } else {
 409                 set save [cc-add-settings $settings]
 410                 set rc [catch {uplevel 1 [lindex $args 0]} result info]
 411                 cc-store-settings $save
 412                 if {$rc != 0} {
 413                         return -code [dict get $info -code] $result
 414                 }
 415                 return $result
 416         }
 417 }
 418
 419 # @cctest ?settings?
 420 #
 421 # Low level C/C++ compiler checker. Compiles and or links a small C program
 422 # according to the arguments and returns 1 if OK, or 0 if not.
 423 #
 424 # Supported settings are:
 425 #
 426 ## -cflags cflags      A list of flags to pass to the compiler
 427 ## -includes list      A list of includes, e.g. {stdlib.h stdio.h}
 428 ## -declare code       Code to declare before main()
 429 ## -link 1             Don't just compile, link too
 430 ## -lang c|c++         Use the C (default) or C++ compiler
 431 ## -libs liblist       List of libraries to link, e.g. {-ldl -lm}
 432 ## -code code          Code to compile in the body of main()
 433 ## -source code        Compile a complete program. Ignore -includes, -declare and -code
 434 ## -sourcefile file    Shorthand for -source [readfile [get-define srcdir]/$file]
 435 ## -nooutput 1         Treat any compiler output (e.g. a warning) as an error
 436 #
 437 # Unless '-source' or '-sourcefile' is specified, the C program looks like:
 438 #
 439 ## #include <firstinclude>   /* same for remaining includes in the list */
 440 ##
 441 ## declare-code              /* any code in -declare, verbatim */
 442 ##
 443 ## int main(void) {
 444 ##   code                    /* any code in -code, verbatim */
 445 ##   return 0;
 446 ## }
 447 #
 448 # Any failures are recorded in 'config.log'
 449 #
 450 proc cctest {args} {
 451         set src conftest__.c
 452         set tmp conftest__
 453
 454         # Easiest way to merge in the settings
 455         cc-with $args {
 456                 array set opts [cc-get-settings]
 457         }
 458
 459         if {[info exists opts(-sourcefile)]} {
 460                 set opts(-source) [readfile [get-define srcdir]/$opts(-sourcefile) "#error can't find $opts(-sourcefile)"]
 461         }
 462         if {[info exists opts(-source)]} {
 463                 set lines $opts(-source)
 464         } else {
 465                 foreach i $opts(-includes) {
 466                         if {$opts(-code) ne "" && ![feature-checked $i]} {
 467                                 # Compiling real code with an unchecked header file
 468                                 # Quickly (and silently) check for it now
 469
 470                                 # Remove all -includes from settings before checking
 471                                 set saveopts [cc-update-settings -includes {}]
 472                                 msg-quiet cc-check-includes $i
 473                                 cc-store-settings $saveopts
 474                         }
 475                         if {$opts(-code) eq "" || [have-feature $i]} {
 476                                 lappend source "#include <$i>"
 477                         }
 478                 }
 479                 lappend source {*}$opts(-declare)
 480                 lappend source "int main(void) {"
 481                 lappend source $opts(-code)
 482                 lappend source "return 0;"
 483                 lappend source "}"
 484
 485                 set lines [join $source \n]
 486         }
 487
 488         # Build the command line
 489         set cmdline {}
 490         lappend cmdline {*}[get-define CCACHE]
 491         switch -exact -- $opts(-lang) {
 492                 c++ {
 493                         lappend cmdline {*}[get-define CXX] {*}[get-define CXXFLAGS]
 494                 }
 495                 c {
 496                         lappend cmdline {*}[get-define CC] {*}[get-define CFLAGS]
 497                 }
 498                 default {
 499                         autosetup-error "cctest called with unknown language: $opts(-lang)"
 500                 }
 501         }
 502
 503         if {$opts(-link)} {
 504                 lappend cmdline {*}[get-define LDFLAGS]
 505         } else {
 506                 set tmp conftest__.o
 507                 lappend cmdline -c
 508         }
 509         lappend cmdline {*}$opts(-cflags) {*}[get-define cc-default-debug ""]
 510         lappend cmdline $src -o $tmp {*}$opts(-libs)
 511         if {$opts(-link)} {
 512                 lappend cmdline {*}[get-define LIBS]
 513         }
 514
 515         # At this point we have the complete command line and the
 516         # complete source to be compiled. Get the result from cache if
 517         # we can
 518         if {[info exists ::cc_cache($cmdline,$lines)]} {
 519                 msg-checking "(cached) "
 520                 set ok $::cc_cache($cmdline,$lines)
 521                 if {$::autosetup(debug)} {
 522                         configlog "From cache (ok=$ok): [join $cmdline]"
 523                         configlog "============"
 524                         configlog $lines
 525                         configlog "============"
 526                 }
 527                 return $ok
 528         }
 529
 530         writefile $src $lines\n
 531
 532         set ok 1
 533         set err [catch {exec-with-stderr {*}$cmdline} result errinfo]
 534         if {$err || ($opts(-nooutput) && [string length $result])} {
 535                 configlog "Failed: [join $cmdline]"
 536                 configlog $result
 537                 configlog "============"
 538                 configlog "The failed code was:"
 539                 configlog $lines
 540                 configlog "============"
 541                 set ok 0
 542         } elseif {$::autosetup(debug)} {
 543                 configlog "Compiled OK: [join $cmdline]"
 544                 configlog "============"
 545                 configlog $lines
 546                 configlog "============"
 547         }
 548         file delete $src
 549         file delete $tmp
 550
 551         # cache it
 552         set ::cc_cache($cmdline,$lines) $ok
 553
 554         return $ok
 555 }
 556
 557 # @make-autoconf-h outfile ?auto-patterns=HAVE_*? ?bare-patterns=SIZEOF_*?
 558 #
 559 # Deprecated - see 'make-config-header'
 560 proc make-autoconf-h {file {autopatterns {HAVE_*}} {barepatterns {SIZEOF_* HAVE_DECL_*}}} {
 561         user-notice "*** make-autoconf-h is deprecated -- use make-config-header instead"
 562         make-config-header $file -auto $autopatterns -bare $barepatterns
 563 }
 564
 565 # @make-config-header outfile ?-auto patternlist? ?-bare patternlist? ?-none patternlist? ?-str patternlist? ...
 566 #
 567 # Examines all defined variables which match the given patterns
 568 # and writes an include file, '$file', which defines each of these.
 569 # Variables which match '-auto' are output as follows:
 570 # - defines which have the value '0' are ignored.
 571 # - defines which have integer values are defined as the integer value.
 572 # - any other value is defined as a string, e.g. '"value"'
 573 # Variables which match '-bare' are defined as-is.
 574 # Variables which match '-str' are defined as a string, e.g. '"value"'
 575 # Variables which match '-none' are omitted.
 576 #
 577 # Note that order is important. The first pattern that matches is selected.
 578 # Default behaviour is:
 579 #
 580 ##  -bare {SIZEOF_* HAVE_DECL_*} -auto HAVE_* -none *
 581 #
 582 # If the file would be unchanged, it is not written.
 583 proc make-config-header {file args} {
 584         set guard _[string toupper [regsub -all {[^a-zA-Z0-9]} [file tail $file] _]]
 585         file mkdir [file dirname $file]
 586         set lines {}
 587         lappend lines "#ifndef $guard"
 588         lappend lines "#define $guard"
 589
 590         # Add some defaults
 591         lappend args -bare {SIZEOF_* HAVE_DECL_*} -auto HAVE_*
 592
 593         foreach n [lsort [dict keys [all-defines]]] {
 594                 set value [get-define $n]
 595                 set type [calc-define-output-type $n $args]
 596                 switch -exact -- $type {
 597                         -bare {
 598                                 # Just output the value unchanged
 599                         }
 600                         -none {
 601                                 continue
 602                         }
 603                         -str {
 604                                 set value \"[string map [list \\ \\\\ \" \\\"] $value]\"
 605                         }
 606                         -auto {
 607                                 # Automatically determine the type
 608                                 if {$value eq "0"} {
 609                                         lappend lines "/* #undef $n */"
 610                                         continue
 611                                 }
 612                                 if {![string is integer -strict $value]} {
 613                                         set value \"[string map [list \\ \\\\ \" \\\"] $value]\"
 614                                 }
 615                         }
 616                         "" {
 617                                 continue
 618                         }
 619                         default {
 620                                 autosetup-error "Unknown type in make-config-header: $type"
 621                         }
 622                 }
 623                 lappend lines "#define $n $value"
 624         }
 625         lappend lines "#endif"
 626         set buf [join $lines \n]
 627         write-if-changed $file $buf {
 628                 msg-result "Created $file"
 629         }
 630 }
 631
 632 proc calc-define-output-type {name spec} {
 633         foreach {type patterns} $spec {
 634                 foreach pattern $patterns {
 635                         if {[string match $pattern $name]} {
 636                                 return $type
 637                         }
 638                 }
 639         }
 640         return ""
 641 }
 642
 643 # Initialise some values from the environment or commandline or default settings
 644 foreach i {LDFLAGS LIBS CPPFLAGS LINKFLAGS {CFLAGS "-g -O2"}} {
 645         lassign $i var default
 646         define $var [get-env $var $default]
 647 }
 648
 649 if {[env-is-set CC]} {
 650         # Set by the user, so don't try anything else
 651         set try [list [get-env CC ""]]
 652 } else {
 653         # Try some reasonable options
 654         set try [list [get-define cross]cc [get-define cross]gcc]
 655 }
 656 define CC [find-an-executable {*}$try]
 657 if {[get-define CC] eq ""} {
 658         user-error "Could not find a C compiler. Tried: [join $try ", "]"
 659 }
 660
 661 define CPP [get-env CPP "[get-define CC] -E"]
 662
 663 # XXX: Could avoid looking for a C++ compiler until requested
 664 # Note that if CXX isn't found, we just set it to "false". It might not be needed.
 665 if {[env-is-set CXX]} {
 666         define CXX [find-an-executable -required [get-env CXX ""]]
 667 } else {
 668         define CXX [find-an-executable [get-define cross]c++ [get-define cross]g++ false]
 669 }
 670
 671 # CXXFLAGS default to CFLAGS if not specified
 672 define CXXFLAGS [get-env CXXFLAGS [get-define CFLAGS]]
 673
 674 # May need a CC_FOR_BUILD, so look for one
 675 define CC_FOR_BUILD [find-an-executable [get-env CC_FOR_BUILD ""] cc gcc false]
 676
 677 if {[get-define CC] eq ""} {
 678         user-error "Could not find a C compiler. Tried: [join $try ", "]"
 679 }
 680
 681 define CCACHE [find-an-executable [get-env CCACHE ccache]]
 682
 683 # Initial cctest settings
 684 cc-store-settings {-cflags {} -includes {} -declare {} -link 0 -lang c -libs {} -code {} -nooutput 0}
 685 set autosetup(cc-include-deps) {}
 686
 687 msg-result "C compiler...[get-define CCACHE] [get-define CC] [get-define CFLAGS]"
 688 if {[get-define CXX] ne "false"} {
 689         msg-result "C++ compiler...[get-define CCACHE] [get-define CXX] [get-define CXXFLAGS]"
 690 }
 691 msg-result "Build C compiler...[get-define CC_FOR_BUILD]"
 692
 693 # On Darwin, we prefer to use -g0 to avoid creating .dSYM directories
 694 # but some compilers may not support it, so test here.
 695 switch -glob -- [get-define host] {
 696         *-*-darwin* {
 697                 if {[cctest -cflags {-g0}]} {
 698                         define cc-default-debug -g0
 699                 }
 700         }
 701 }
 702
 703 if {![cc-check-includes stdlib.h]} {
 704         user-error "Compiler does not work. See config.log"
 705 }