On 11/27/2016 08:34 PM, Martin Sebor wrote:
PR 78521 notes that the gimple-ssa-sprintf pass doesn't do the right thing (i.e., the -Wformat-length and -fprintf-return-value options behave incorrectly) when a conversion specification includes a width or precision with a non-constant value. The code treats such cases as if they were not provided which is incorrect and results in the wrong bytes counts in warning messages and in the wrong ranges being generated for such calls (or in the case sprintf(0, 0, ...) for some such calls being eliminated).The attached patch corrects the handling of these cases, plus a couple of other edge cases in the same area: it adjusts the parser to accept precision in the form of just a period with no asterisk or decimal digits after it (this sets the precision to zero), and corrects the handling of zero precision and zero argument in integer directives to produce no bytes on output. Finally, the patch also tightens up the constraint on the upper bound of bounded functions like snprintf to be INT_MAX. The functions cannot produce output in excess of INT_MAX + 1 bytes and some implementations (e.g., Solaris) fail with EINVAL when the bound is INT_MAX or more. This is the subject of PR 78520. Thanks Martin gcc-78521.diff PR middle-end/78521 - [7 Regression] incorrect byte count in -Wformat-length warning with non-constant width or precision PR middle-end/78520 - missing warning for snprintf with size greater than INT_MAX gcc/ChangeLog: PR middle-end/78521 PR middle-end/78520 * gimple-ssa-sprintf.c (target_max_value): Remove. (target_int_max, target_size_max): Use TYPE_MAX_VALUE. (get_width_and_precision): New function. (format_integer, format_floating, get_string_length, format_string): Correct handling of width and precision with unknown value. (format_directive): Add warning. (pass_sprintf_length::compute_format_length): Allow for precision to consist of a sole period with no asterisk or digits after it. gcc/testsuite/ChangeLog: PR middle-end/78521 PR middle-end/78520 * gcc.dg/tree-ssa/builtin-sprintf-5.c: Add test cases. * gcc.dg/tree-ssa/builtin-sprintf-6.c: New test. * gcc.dg/tree-ssa/builtin-sprintf-warn-1.c: Add test cases. * gcc.dg/tree-ssa/builtin-sprintf-warn-3.c: Add test cases.
Fairly dense reading. Probably inherent due to the problem space. OK for the trunk. Thanks, jeff
