PR middle-end/79692 - [7 Regression] -Wformat-overflow false positive

PR middle-end/79692 - [7 Regression] -Wformat-overflow false positive

gcc/ChangeLog:

	PR middle-end/79692
	* gimple-ssa-sprintf.c
	(directive::known_width_and_precision): New function.
	(format_integer): Use it.
	(get_mpfr_format_length): Consider the full range of precision
	when computing %g output with the # flag.  Set the likely byte
	count to 3 rather than 1 when precision is indeterminate.
	(format_floating): Correct the lower bound of precision.

gcc/testsuite/ChangeLog:

	PR middle-end/79692
	* gcc.dg/tree-ssa/builtin-sprintf-2.c: Add test cases.
	* gcc.dg/tree-ssa/builtin-sprintf-warn-10.c: Correct %#g.
	* gcc.dg/tree-ssa/builtin-sprintf-warn-15.c: New test.
	* gcc.dg/tree-ssa/builtin-snprintf-3.c: Ditto.

From-SVN: r245822