gdb 8.0 "lazy_string" exception "Length is larger than array size"

[Michael Stahl <mstahl at redhat dot com>]

hi,

for the following string type:

  /** The implementation of a Unicode string.
  */
  typedef struct SAL_DLLPUBLIC_RTTI _rtl_uString
  {
      oslInterlockedCount refCount; /* opaque */
      sal_Int32           length;
      sal_Unicode         buffer[1];
  } rtl_uString;

the gdb python pretty-printer calls:

	return data.lazy_string(encoding, length)

full python pretty-printer module:

https://gerrit.libreoffice.org/gitweb?p=core.git;a=blob;f=solenv/gdb/libreoffice/util/string.py;h=32583718f83b2ad5707f75dd6327d9aa62764439;hb=5f210715fe090b4db4c80dcdee5f77dc404cf85c#l56

now this results in this exception:

  Traceback (most recent call last):
    File "/work/lo/master/solenv/gdb/libreoffice/util/string.py", line
29, in to_string
      return self.make_string(data, self.encoding, len)
    File "/work/lo/master/solenv/gdb/libreoffice/util/string.py", line
66, in make_string
      return data.lazy_string(encoding, length)
  gdb.error: Length is larger than array size.

this is with Fedora 26 "GNU gdb (GDB) Fedora 8.0.1-26.fc26" - in Fedora
25 this did not throw an exception.

apparently the problem is that the array is statically declared as
"buffer[1]", however its actual dynamic size is the same as "length".

is this a bug in gdb or is lazy_string not intended to support this
scenario?

regards,
 michael