https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104270
Bug ID: 104270
Summary: -Wanalyzer-use-of-uninitialized-value is incorrectly
suppressed by -ftrivial-auto-var-init=
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Target Milestone: ---
As of GCC 12, the analyzer ought to complain about uses of uninitialized memory
via
-Wanalyzer-use-of-uninitialized-value
but fails to do so for trivial cases of locals when -ftrivial-auto-var-init= is
used with "pattern" or "zero".
The docs for -ftrivial-auto-var-init say:
> GCC still considers an automatic variable that doesn't have an explicit
> initializer as uninitialized, @option{-Wuninitialized} will still report
> warning messages on such automatic variables.
which implies that -ftrivial-auto-var-init is intended for mitigation, and that
the analyzer ought to still warn on such cases.
At the gimple level we have e.g.:
i_1 = .DEFERRED_INIT (4, 1, &"i"[0]);
which the analyzer doesn't yet have any special knowledge about, and thus
treats the result as a normal value, suppressing the warning.
