(stabs.info)Questions


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Questions and Anomalies
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   * For GNU C stabs defining local and global variables (`N_LSYM' and
     `N_GSYM'), 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 `dbxout.c' and
     putting a line number in desc is controlled by `#ifdef
     WINNING_GDB', which defaults to false). GDB supposedly uses this
     information if you say `list VAR'.  In reality, VAR can be a
     variable defined in the program and GDB says `function VAR not
     defined'.

   * In GNU C stabs, there seems to be no way to differentiate tag
     types: structures, unions, and enums (symbol descriptor `T') and
     typedefs (symbol descriptor `t') defined at file scope from types
     defined locally to a procedure or other more local scope.  They
     all use the `N_LSYM' stab type.  Types defined at procedure scope
     are emited after the `N_RBRAC' 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 overcompensates by placing all
     types in block #1, the block for symbols of file scope.  This is
     true for default, `-ansi' and `-traditional' compiler options.
     (Bugs gcc/1063, gdb/1066.)

   * What ends the procedure scope?  Is it the proc block's `N_RBRAC'
     or the next `N_FUN'?  (I believe its the first.)

   * Global variable stabs don't have location information.  This comes
     from the external symbol for the same variable.  The external
     symbol has a leading underbar on the _name of the variable and the
     stab does not.  How do we know these two symbol table entries are
     talking about the same symbol when their names are different?
     (Answer: the debugger knows that external symbols have leading
     underbars).


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