gcc/d/doc/invoking-gdc/warnings.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. index:: options to control warnings, warning messages, messages, warning, suppressing warnings
   7
   8 .. _warnings:
   9
  10 Warnings
  11 ********
  12
  13 Warnings are diagnostic messages that report constructions that
  14 are not inherently erroneous but that are risky or suggest there
  15 is likely to be a bug in the program.  Unless :option:`-Werror` is
  16 specified, they do not prevent compilation of the program.
  17
  18 .. option:: -Wall
  19
  20   .. index:: -Wall, -Wno-all
  21
  22   Turns on all warnings messages.  Warnings are not a defined part of
  23   the D language, and all constructs for which this may generate a
  24   warning message are valid code.
  25
  26 .. option:: -Walloca
  27
  28   .. index:: -Walloca
  29
  30   This option warns on all uses of "alloca" in the source.
  31
  32 .. option:: -Walloca-larger-than=n
  33
  34   .. index:: -Walloca-larger-than, -Wno-alloca-larger-than
  35
  36   Warn on unbounded uses of alloca, and on bounded uses of alloca
  37   whose bound can be larger than :samp:`{n}` bytes.
  38   :option:`-Wno-alloca-larger-than` disables
  39   :option:`-Walloca-larger-than` warning and is equivalent to
  40   :option:`-Walloca-larger-than=SIZE_MAX` or larger.
  41
  42 .. option:: -Wcast-result
  43
  44   .. index:: -Wcast-result, -Wno-cast-result
  45
  46   Warn about casts that will produce a null or zero result.  Currently
  47   this is only done for casting between an imaginary and non-imaginary
  48   data type, or casting between a D and C++ class.
  49
  50 .. option:: -Wno-deprecated
  51
  52   .. index:: -Wdeprecated, -Wno-deprecated
  53
  54   Do not warn about usage of deprecated features and symbols with
  55   ``deprecated`` attributes.
  56
  57 .. option:: -Werror
  58
  59   .. index:: -Werror, -Wno-error
  60
  61   Turns all warnings into errors.
  62
  63 .. option:: -Wspeculative
  64
  65   .. index:: -Wspeculative, -Wno-speculative
  66
  67   List all error messages from speculative compiles, such as
  68   ``__traits(compiles, ...)``.  This option does not report
  69   messages as warnings, and these messages therefore never become
  70   errors when the :option:`-Werror` option is also used.
  71
  72 .. option:: -Wtemplates
  73
  74   .. index:: -Wtemplates, -Wno-templates
  75
  76   Warn when a template instantiation is encountered.  Some coding
  77   rules disallow templates, and this may be used to enforce that rule.
  78
  79 .. option:: -Wunknown-pragmas
  80
  81   .. index:: -Wunknown-pragmas, -Wno-unknown-pragmas
  82
  83   Warn when a ``pragma()`` is encountered that is not understood by
  84   :command:`gdc`.  This differs from :option:`-fignore-unknown-pragmas`
  85   where a pragma that is part of the D language, but not implemented by
  86   the compiler, won't get reported.
  87
  88 .. option:: -Wno-varargs
  89
  90   .. index:: Wvarargs, Wno-varargs
  91
  92   Do not warn upon questionable usage of the macros used to handle variable
  93   arguments like ``va_start``.
  94
  95 .. option:: -fignore-unknown-pragmas
  96
  97   .. index:: -fignore-unknown-pragmas, -fno-ignore-unknown-pragmas
  98
  99   Turns off errors for unsupported pragmas.
 100
 101 .. option:: -fmax-errors=n
 102
 103   .. index:: -fmax-errors
 104
 105   Limits the maximum number of error messages to :samp:`{n}`, at which point
 106   :command:`gdc` bails out rather than attempting to continue processing the
 107   source code.  If :samp:`{n}` is 0 (the default), there is no limit on the
 108   number of error messages produced.
 109
 110 .. option:: -fsyntax-only
 111
 112   .. index:: -fsyntax-only, -fno-syntax-only
 113
 114   Check the code for syntax errors, but do not actually compile it.  This
 115   can be used in conjunction with :option:`-fdoc` or :option:`-H` to generate
 116   files for each module present on the command-line, but no other output
 117   file.
 118
 119 .. option:: -ftransition=id
 120
 121   .. index:: -ftransition
 122
 123   Report additional information about D language changes identified by
 124   :samp:`{id}`.  The following values are supported:
 125
 126   :samp:`all`
 127     List information on all D language transitions.
 128
 129   :samp:`complex`
 130     List all usages of complex or imaginary types.
 131
 132   :samp:`field`
 133     List all non-mutable fields which occupy an object instance.
 134
 135   :samp:`in`
 136     List all usages of ``in`` on parameter.
 137
 138   :samp:`nogc`
 139     List all hidden GC allocations.
 140
 141   :samp:`templates`
 142     List statistics on template instantiations.
 143
 144   :samp:`tls`
 145     List all variables going into thread local storage.
 146
 147   :samp:`vmarkdown`
 148     List instances of Markdown replacements in Ddoc.