April/May 2016 GNU Toolchain Update

[Nick Clifton <nickc at redhat dot com>]

Hi Guys,

  Well now that GCC 6 is out lets see what new features have started
  to appear in the toolchain:

  Several new warning options have been added to GCC:
  
  * The option -Wno-duplicate-decl-specifier has been added to
    generate warnings whenever a declaration contains duplicate const,
    volatile, restrict or _Atomic specifiers.  This warning is enabled
    by -Wall.

  * The option -Wignored-attributes warns when an attribute is
    correctly assigned, but the compiler decided to ignore it anyway.
    This is different from the -Wattributes which warns when an
    attribute is either unknown or used in the wrong place.

  * The option -Wswitch-unreachable warns whenever a switch statement
    contains statements between the controlling expression and the
    first case label, which will never be executed.  For example:

      switch (cond)
        {
          i = 15;
          case 5:
             <code>

    The option does not warn if the statement(s) between the
    controlling expression and the first case label are just variable
    declarations:

      switch (cond)
        {
          int i;
          case 5:
             <code>

  * The option -Wdangling-else warns about constructions where there
    may be confusion to which if statement an else branch belongs.
    For example:

       if (a)
         if (b)
           foo ();
       else
         bar ();

  * The option -Wmemset-elt-size warns about suspicious calls to
    the memset function, if the first argument references an array,
    and the third argument is a number equal to the number of
    elements, but not equal to the size of the array in memory.
    For example:

      int array[10];
      memset (array, 0, 10);  // Should be: memset (array, 0, 10 * sizeof (int));


  A new point release of GDB is out: 7.11.1.  This is a bugfix release
  addressing these issues:

    * PR remote/19863 (7.10 regression: gdb remote.c due to "setfs" with
      gdbserver < 7.7)
    * PR gdb/19829 (gdb crashes with PT and reverse next)
    * PR gdb/19676 (gdb fails with assert error if /proc is not mounted)
    * PR gdb/19828 (7.11 regression: non-stop gdb -p <process from a
      container>: internal error)
    * PR remote/19840 (gdb crashes on reverse-stepi)
    * PR gdb/19858 (GDB doesn't register the JIT libraries on attach)
    * PR gdb/19958 (Breakpoints/watchpoints broken on MIPS Linux <= 4.5)
    * PR build/20029 (symfile.c ambiguous else warning)
    * PR python/20037 (GDB use-after-free error)
    * PR gdb/20039 (Using MI/all-stop, can't interrupt multi-threaded
      program after continue)a

  In the development GDB sources a couple of new features have been
  added:
  
    * Fortran: Support structures with fields of dynamic types and 
      arrays of dynamic types.

    * Rust language support.
      GDB now supports debugging programs written in the Rust
      programming language.


  Development in the binutils has mostly concentrated on bugfixing,
  but there have been a few new features added:

  * The ARM port of GAS now has support for the ARMv8-M architecture,
    including the security and DSP extensions.

  * The ARC port of GAS now accepts .extInstruction, .extCondCode, 
    .extAuxRegister, and .extCoreRegister pseudo-ops that allow an
    user to define custom instructions, conditional codes, auxiliary
    and core registers.

  * The MIPS port of GAS can now generate code for the DSP Release 3
    Application Specific Extension.

  * Linker scripts can now use a NOCROSSREFSTO directive.  This is
    like the NOCROSSREFS directive which ensures that two or more
    output sections are entirely independent from each other, except
    that it does allow one way referencing. The NOCROSSREFS_TO
    directive takes a list of output section names and complains if
    the first section is referenced from any of the other sections. 

Cheers
  Nick