Hello,

Currently, on an input such as "88888888888:", GAS hits a signed integer
overflow and (likely) an assertion failure. I see:

$ echo "88888888888:" | bin/aarch64-none-elf-as
{standard input}: Assembler messages:
{standard input}:1: Internal error in fb_label_name at ../gas/symbols.c:2049.
Please report this bug.

To fix this issue, I've taken two steps:

1. Change the type used for processing local labels in
   read_a_source_file() from int to long, to allow representing more
   local labels, and also since all uses of this variable (temp) are
   actually of type long.

2. Detect if we would overflow and bail out with an error message
   instead of actually overflowing and hitting the assertion in
   fb_label_name().

Testing:
 * Regression tested on a broad selection of targets.

OK for master?

Thanks,
Alex

---

gas/ChangeLog:

2020-08-05  Alex Coplan  <alex.coplan@arm.com>

	* read.c (read_a_source_file): Use long for local labels, detect
	overflow and raise an error for overly-long labels.
	* testsuite/gas/all/gas.exp: Add local-label-overflow test.
	* testsuite/gas/all/local-label-overflow.d: New test.
	* testsuite/gas/all/local-label-overflow.l: Error output.
	* testsuite/gas/all/local-label-overflow.s: Input.