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| <h2 class="appendix">Appendix E Questions and Anomalies</h2> |
| |
| <ul> |
| <li><!-- I think this is changed in GCC 2.4.5 to put the line number there. --> |
| For GNU C stabs defining local and global variables (<code>N_LSYM</code> and |
| <code>N_GSYM</code>), the desc field is supposed to contain the source |
| line number on which the variable is defined. In reality the desc |
| field is always 0. (This behavior is defined in <samp><span class="file">dbxout.c</span></samp> and |
| putting a line number in desc is controlled by ‘<samp><span class="samp">#ifdef |
| WINNING_GDB</span></samp>’, which defaults to false). GDB supposedly uses this |
| information if you say ‘<samp><span class="samp">list </span><var>var</var></samp>’. In reality, <var>var</var> can |
| be a variable defined in the program and GDB says ‘<samp><span class="samp">function |
| </span><var>var</var><span class="samp"> not defined</span></samp>’. |
| |
| <li>In GNU C stabs, there seems to be no way to differentiate tag types: |
| structures, unions, and enums (symbol descriptor ‘<samp><span class="samp">T</span></samp>’) and typedefs |
| (symbol descriptor ‘<samp><span class="samp">t</span></samp>’) defined at file scope from types defined locally |
| to a procedure or other more local scope. They all use the <code>N_LSYM</code> |
| stab type. Types defined at procedure scope are emitted after the |
| <code>N_RBRAC</code> of the preceding function and before the code of the |
| procedure in which they are defined. This is exactly the same as |
| types defined in the source file between the two procedure bodies. |
| GDB over-compensates by placing all types in block #1, the block for |
| symbols of file scope. This is true for default, ‘<samp><span class="samp">-ansi</span></samp>’ and |
| ‘<samp><span class="samp">-traditional</span></samp>’ compiler options. (Bugs gcc/1063, gdb/1066.) |
| |
| <li>What ends the procedure scope? Is it the proc block's <code>N_RBRAC</code> or the |
| next <code>N_FUN</code>? (I believe its the first.) |
| </ul> |
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