1GDC(1) GNU GDC(1)
2
6 gdc - A GCC-based compiler for the D language
7
9 gdc [-c|-S] [-g] [-pg]
10 [-Olevel] [-Wwarn...]
11 [-Idir...] [-Ldir...]
12 [-foption...] [-mmachine-option...]
13 [-o outfile] [@file] infile...
14 Only the most useful options are listed here; see below for the
16 remainder.
17
19 The gdc command is the GNU compiler for the D language and supports
20 many of the same options as gcc. This manual only documents the
21 options specific to gdc.
22
24 Input and Output files
25 For any given input file, the file name suffix determines what kind of
26 compilation is done. The following kinds of input file names are
27 supported:
28 file.d
30 D source files.
31 file.dd
33 Ddoc source files.
34 file.di
36 D interface files.
37 You can specify more than one input file on the gdc command line, each
39 being compiled separately in the compilation process. If you specify a
40 "-o file" option, all the input files are compiled together, producing
41 a single output file, named file. This is allowed even when using "-S"
42 or "-c".
43 A D interface file contains only what an import of the module needs,
45 rather than the whole implementation of that module. They can be
46 created by gdc from a D source file by using the "-H" option. When the
47 compiler resolves an import declaration, it searches for matching .di
48 files first, then for .d.
49 A Ddoc source file contains code in the D macro processor language. It
51 is primarily designed for use in producing user documentation from
52 embedded comments, with a slight affinity towards HTML generation. If
53 a .d source file starts with the string "Ddoc" then it is treated as
54 general purpose documentation, not as a D source file.
55 Runtime Options
57 These options affect the runtime behavior of programs compiled with
58 gdc.
59 -fall-instantiations
61 Generate code for all template instantiations. The default
62 template emission strategy is to not generate code for declarations
63 that were either instantiated speculatively, such as from
64 "__traits(compiles, ...)", or that come from an imported module not
65 being compiled.
66 -fno-assert
68 Turn off code generation for "assert" contracts.
69 -fno-bounds-check
71 Turns off array bounds checking for all functions, which can
72 improve performance for code that uses arrays extensively. Note
73 that this can result in unpredictable behavior if the code in
74 question actually does violate array bounds constraints. It is
75 safe to use this option if you are sure that your code never throws
76 a "RangeError".
77 -fbounds-check=value
79 An alternative to -fbounds-check that allows more control as to
80 where bounds checking is turned on or off. The following values
81 are supported:
82 on Turns on array bounds checking for all functions.
84 safeonly
86 Turns on array bounds checking only for @safe functions.
87 off Turns off array bounds checking completely.
89 -fno-builtin
91 Don't recognize built-in functions unless they begin with the
92 prefix __builtin_. By default, the compiler will recognize when a
93 function in the "core.stdc" package is a built-in function.
94 -fdebug
96 -fdebug=value
97 Turn on compilation of conditional "debug" code into the program.
98 The -fdebug option itself sets the debug level to 1, while -fdebug=
99 enables "debug" code that are identified by any of the following
100 values:
101 level
103 Sets the debug level to level, any "debug" code <= level is
104 compiled into the program.
105 ident
107 Turns on compilation of any "debug" code identified by ident.
108 -fno-druntime
110 Implements <https://dlang.org/spec/betterc.html>. Assumes that
111 compilation targets an environment without a D runtime library.
112 This is equivalent to compiling with the following options:
114 gdc -nophoboslib -fno-exceptions -fno-moduleinfo -fno-rtti
116 -fno-invariants
118 Turns off code generation for class "invariant" contracts.
119 -fno-moduleinfo
121 Turns off generation of the "ModuleInfo" and related functions that
122 would become unreferenced without it, which may allow linking to
123 programs not written in D. Functions that are not be generated
124 include module constructors and destructors ("static this" and
125 "static ~this"), "unittest" code, and "DSO" registry functions for
126 dynamically linked code.
127 -fonly=filename
129 Tells the compiler to parse and run semantic analysis on all
130 modules on the command line, but only generate code for the module
131 specified by filename.
132 -fno-postconditions
134 Turns off code generation for postcondition "out" contracts.
135 -fno-preconditions
137 Turns off code generation for precondition "in" contracts.
138 -frelease
140 Turns on compiling in release mode, which means not emitting
141 runtime checks for contracts and asserts. Array bounds checking is
142 not done for @system and @trusted functions, and assertion failures
143 are undefined behavior.
144 This is equivalent to compiling with the following options:
146 gdc -fno-assert -fbounds-check=safe -fno-invariants \
148 -fno-postconditions -fno-preconditions -fno-switch-errors
149 -fno-rtti
151 Turns off generation of run-time type information for all user
152 defined types. Any code that uses features of the language that
153 require access to this information will result in an error.
154 -fno-switch-errors
156 This option controls what code is generated when no case is matched
157 in a "final switch" statement. The default run time behavior is to
158 throw a "SwitchError". Turning off -fswitch-errors means that
159 instead the execution of the program is immediately halted.
160 -funittest
162 Turns on compilation of "unittest" code, and turns on the
163 "version(unittest)" identifier. This implies -fassert.
164 -fversion=value
166 Turns on compilation of conditional "version" code into the program
167 identified by any of the following values:
168 level
170 Sets the version level to level, any "version" code >= level is
171 compiled into the program.
172 ident
174 Turns on compilation of "version" code identified by ident.
175 -fno-weak-templates
177 Turns off emission of declarations that can be defined in multiple
178 objects as weak symbols. The default is to emit all public symbols
179 as weak, unless the target lacks support for weak symbols.
180 Disabling this option means that common symbols are instead put in
181 COMDAT or become private.
182 Options for Directory Search
184 These options specify directories to search for files, libraries, and
185 other parts of the compiler:
186 -Idir
188 Specify a directory to use when searching for imported modules at
189 compile time. Multiple -I options can be used, and the paths are
190 searched in the same order.
191 -Jdir
193 Specify a directory to use when searching for files in string
194 imports at compile time. This switch is required in order to use
195 "import(file)" expressions. Multiple -J options can be used, and
196 the paths are searched in the same order.
197 -Ldir
199 When linking, specify a library search directory, as with gcc.
200 -Bdir
202 This option specifies where to find the executables, libraries,
203 source files, and data files of the compiler itself, as with gcc.
204 -fmodule-file=module=spec
206 This option manipulates file paths of imported modules, such that
207 if an imported module matches all or the leftmost part of module,
208 the file path in spec is used as the location to search for D
209 sources. This is used when the source file path and names are not
210 the same as the package and module hierarchy. Consider the
211 following examples:
212 gdc test.d -fmodule-file=A.B=foo.d -fmodule-file=C=bar
214 This will tell the compiler to search in all import paths for the
216 source file foo.d when importing A.B, and the directory bar/ when
217 importing C, as annotated in the following D code:
218 module test;
220 import A.B; // Matches A.B, searches for foo.d
221 import C.D.E; // Matches C, searches for bar/D/E.d
222 import A.B.C; // No match, searches for A/B/C.d
223 -imultilib dir
225 Use dir as a subdirectory of the gcc directory containing target-
226 specific D sources and interfaces.
227 -iprefix prefix
229 Specify prefix as the prefix for the gcc directory containing
230 target-specific D sources and interfaces. If the prefix represents
231 a directory, you should include the final '/'.
232 -nostdinc
234 Do not search the standard system directories for D source and
235 interface files. Only the directories that have been specified
236 with -I options (and the directory of the current file, if
237 appropriate) are searched.
238 Code Generation
240 In addition to the many gcc options controlling code generation, gdc
241 has several options specific to itself.
242 -H Generates D interface files for all modules being compiled. The
244 compiler determines the output file based on the name of the input
245 file, removes any directory components and suffix, and applies the
246 .di suffix.
247 -Hd dir
249 Same as -H, but writes interface files to directory dir. This
250 option can be used with -Hf file to independently set the output
251 file and directory path.
252 -Hf file
254 Same as -H but writes interface files to file. This option can be
255 used with -Hd dir to independently set the output file and
256 directory path.
257 -M Output the module dependencies of all source files being compiled
259 in a format suitable for make. The compiler outputs one make rule
260 containing the object file name for that source file, a colon, and
261 the names of all imported files.
262 -MM Like -M but does not mention imported modules from the D standard
264 library package directories.
265 -MF file
267 When used with -M or -MM, specifies a file to write the
268 dependencies to. When used with the driver options -MD or -MMD,
269 -MF overrides the default dependency output file.
270 -MG This option is for compatibility with gcc, and is ignored by the
272 compiler.
273 -MP Outputs a phony target for each dependency other than the modules
275 being compiled, causing each to depend on nothing.
276 -MT target
278 Change the target of the rule emitted by dependency generation to
279 be exactly the string you specify. If you want multiple targets,
280 you can specify them as a single argument to -MT, or use multiple
281 -MT options.
282 -MQ target
284 Same as -MT, but it quotes any characters which are special to
285 make.
286 -MD This option is equivalent to -M -MF file. The driver determines
288 file by removing any directory components and suffix from the input
289 file, and then adding a .deps suffix.
290 -MMD
292 Like -MD but does not mention imported modules from the D standard
293 library package directories.
294 -X Output information describing the contents of all source files
296 being compiled in JSON format to a file. The driver determines
297 file by removing any directory components and suffix from the input
298 file, and then adding a .json suffix.
299 -Xf file
301 Same as -X, but writes all JSON contents to the specified file.
302 -fdoc
304 Generates "Ddoc" documentation and writes it to a file. The
305 compiler determines file by removing any directory components and
306 suffix from the input file, and then adding a .html suffix.
307 -fdoc-dir=dir
309 Same as -fdoc, but writes documentation to directory dir. This
310 option can be used with -fdoc-file=file to independently set the
311 output file and directory path.
312 -fdoc-file=file
314 Same as -fdoc, but writes documentation to file. This option can
315 be used with -fdoc-dir=dir to independently set the output file and
316 directory path.
317 -fdoc-inc=file
319 Specify file as a Ddoc macro file to be read. Multiple -fdoc-inc
320 options can be used, and files are read and processed in the same
321 order.
322 Warnings
324 Warnings are diagnostic messages that report constructions that are not
325 inherently erroneous but that are risky or suggest there is likely to
326 be a bug in the program. Unless -Werror is specified, they do not
327 prevent compilation of the program.
328 -Wall
330 Turns on all warnings messages. Warnings are not a defined part of
331 the D language, and all constructs for which this may generate a
332 warning message are valid code.
333 -Walloca
335 This option warns on all uses of "alloca" in the source.
336 -Walloca-larger-than=n
338 Warn on unbounded uses of alloca, and on bounded uses of alloca
339 whose bound can be larger than n bytes. -Wno-alloca-larger-than
340 disables -Walloca-larger-than warning and is equivalent to
341 -Walloca-larger-than=SIZE_MAX or larger.
342 -Wcast-result
344 Warn about casts that will produce a null or zero result.
345 Currently this is only done for casting between an imaginary and
346 non-imaginary data type, or casting between a D and C++ class.
347 -Wno-deprecated
349 Do not warn about usage of deprecated features and symbols with
350 "deprecated" attributes.
351 -Werror
353 Turns all warnings into errors.
354 -Wspeculative
356 List all error messages from speculative compiles, such as
357 "__traits(compiles, ...)". This option does not report messages as
358 warnings, and these messages therefore never become errors when the
359 -Werror option is also used.
360 -Wtemplates
362 Warn when a template instantiation is encountered. Some coding
363 rules disallow templates, and this may be used to enforce that
364 rule.
365 -Wunknown-pragmas
367 Warn when a "pragma()" is encountered that is not understood by
368 gdc. This differs from -fignore-unknown-pragmas where a pragma
369 that is part of the D language, but not implemented by the
370 compiler, won't get reported.
371 -Wno-varargs
373 Do not warn upon questionable usage of the macros used to handle
374 variable arguments like "va_start".
375 -fignore-unknown-pragmas
377 Turns off errors for unsupported pragmas.
378 -fmax-errors=n
380 Limits the maximum number of error messages to n, at which point
381 gdc bails out rather than attempting to continue processing the
382 source code. If n is 0 (the default), there is no limit on the
383 number of error messages produced.
384 -fsyntax-only
386 Check the code for syntax errors, but do not actually compile it.
387 This can be used in conjunction with -fdoc or -H to generate files
388 for each module present on the command-line, but no other output
389 file.
390 -ftransition=id
392 Report additional information about D language changes identified
393 by id. The following values are supported:
394 all List information on all language changes.
396 complex
398 List all usages of complex or imaginary types.
399 dip1000
401 Implements <http://wiki.dlang.org/DIP1000> (experimental).
402 dip25
404 Implements <http://wiki.dlang.org/DIP25> (experimental).
405 field
407 List all non-mutable fields which occupy an object instance.
408 nogc
410 List all hidden GC allocations.
411 tls List all variables going into thread local storage.
413 Options for Linking
415 These options come into play when the compiler links object files into
416 an executable output file. They are meaningless if the compiler is not
417 doing a link step.
418 -defaultlib=libname
420 Specify the library to use instead of libphobos when linking.
421 Options specifying the linkage of libphobos, such as
422 -static-libphobos or -shared-libphobos, are ignored.
423 -debuglib=libname
425 Specify the debug library to use instead of libphobos when linking.
426 This option has no effect unless the -g option was also given on
427 the command line. Options specifying the linkage of libphobos,
428 such as -static-libphobos or -shared-libphobos, are ignored.
429 -nophoboslib
431 Do not use the Phobos or D runtime library when linking. Options
432 specifying the linkage of libphobos, such as -static-libphobos or
433 -shared-libphobos, are ignored. The standard system libraries are
434 used normally, unless -nostdlib or -nodefaultlibs is used.
435 -shared-libphobos
437 On systems that provide libgphobos and libgdruntime as a shared and
438 a static library, this option forces the use of the shared version.
439 If no shared version was built when the compiler was configured,
440 this option has no effect.
441 -static-libphobos
443 On systems that provide libgphobos and libgdruntime as a shared and
444 a static library, this option forces the use of the static version.
445 If no static version was built when the compiler was configured,
446 this option has no effect.
447 Developer Options
449 This section describes command-line options that are primarily of
450 interest to developers or language tooling.
451 -fdump-d-original
453 Output the internal front-end AST after the "semantic3" stage.
454 This option is only useful for debugging the GNU D compiler itself.
455 -v Dump information about the compiler language processing stages as
457 the source program is being compiled. This includes listing all
458 modules that are processed through the "parse", "semantic",
459 "semantic2", and "semantic3" stages; all "import" modules and their
460 file paths; and all "function" bodies that are being compiled.
461
463 gpl(7), gfdl(7), fsf-funding(7), gcc(1) and the Info entries for gdc
464 and gcc.
465
467 Copyright (c) 2006-2021 Free Software Foundation, Inc.
468 Permission is granted to copy, distribute and/or modify this document
470 under the terms of the GNU Free Documentation License, Version 1.3 or
471 any later version published by the Free Software Foundation; with no
472 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
473 copy of the license is included in the man page gfdl(7).
474gcc-11 2021-05-31 GDC(1)