mingw/info/stabs/Protections.html

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  12 Node:<a name="Protections">Protections</a>,
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  18
  19 <h3 class="section">Protections</h3>
  20
  21    <p>In the simple class definition shown above all member data and
  22 functions were publicly accessible.  The example that follows
  23 contrasts public, protected and privately accessible fields and shows
  24 how these protections are encoded in C++ stabs.
  25
  26    <p>If the character following the <code></code><var>field-name</var><code>:</code> part of the
  27 string is <code>/</code>, then the next character is the visibility.  <code>0</code>
  28 means private, <code>1</code> means protected, and <code>2</code> means public.
  29 Debuggers should ignore visibility characters they do not recognize, and
  30 assume a reasonable default (such as public) (GDB 4.11 does not, but
  31 this should be fixed in the next GDB release).  If no visibility is
  32 specified the field is public.  The visibility <code>9</code> means that the
  33 field has been optimized out and is public (there is no way to specify
  34 an optimized out field with a private or protected visibility).
  35 Visibility <code>9</code> is not supported by GDB 4.11; this should be fixed
  36 in the next GDB release.
  37
  38    <p>The following C++ source:
  39
  40 <pre class="example">     class vis {
  41      private:
  42              int   priv;
  43      protected:
  44              char  prot;
  45      public:
  46              float pub;
  47      };
  48      </pre>
  49
  50 <p>generates the following stab:
  51
  52 <pre class="example">     # 128 is N_LSYM
  53      .stabs "vis:T19=s12priv:/01,0,32;prot:/12,32,8;pub:12,64,32;;",128,0,0,0
  54      </pre>
  55
  56    <p><code>vis:T19=s12</code> indicates that type number 19 is a 12 byte structure
  57 named <code>vis</code> The <code>priv</code> field has public visibility
  58 (<code>/0</code>), type int (<code>1</code>), and offset and size <code>,0,32;</code>.
  59 The <code>prot</code> field has protected visibility (<code>/1</code>), type char
  60 (<code>2</code>) and offset and size <code>,32,8;</code>.  The <code>pub</code> field has
  61 type float (<code>12</code>), and offset and size <code>,64,32;</code>.
  62
  63    <p>Protections for member functions are signified by one digit embedded in
  64 the field part of the stab describing the method.  The digit is 0 if
  65 private, 1 if protected and 2 if public.  Consider the C++ class
  66 definition below:
  67
  68 <pre class="example">     class all_methods {
  69      private:
  70              int   priv_meth(int in){return in;};
  71      protected:
  72              char  protMeth(char in){return in;};
  73      public:
  74              float pubMeth(float in){return in;};
  75      };
  76      </pre>
  77
  78    <p>It generates the following stab.  The digit in question is to the left
  79 of an <code>A</code> in each case.  Notice also that in this case two symbol
  80 descriptors apply to the class name struct tag and struct type.
  81
  82 <pre class="display">     .stabs "class_name:sym_desc(struct tag&amp;type)type_def(21)=
  83              sym_desc(struct)struct_bytes(1)
  84              meth_name::type_def(22)=sym_desc(method)returning(int);
  85              :args(int);protection(private)modifier(normal)virtual(no);
  86              meth_name::type_def(23)=sym_desc(method)returning(char);
  87              :args(char);protection(protected)modifier(normal)virtual(no);
  88              meth_name::type_def(24)=sym_desc(method)returning(float);
  89              :args(float);protection(public)modifier(normal)virtual(no);;",
  90              N_LSYM,NIL,NIL,NIL
  91      </pre>
  92
  93 <pre class="smallexample">     .stabs "all_methods:Tt21=s1priv_meth::22=##1;:i;0A.;protMeth::23=##2;:c;1A.;
  94              pubMeth::24=##12;:f;2A.;;",128,0,0,0
  95      </pre>
  96
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