https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94905
Bug ID: 94905
Summary: Bogus warning -Werror=maybe-uninitialized
Product: gcc
Version: 9.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: bug-apl at gnu dot org
Target Milestone: ---
Hi,
as of g++ 9.3.0 when building GNU APL, g++ emits bogus warnings of type
-Werror=maybe-uninitialized.
Apparently the compiler issues these warnings simply because it is lacking
enough context to really figure out what is happening (e.g. if the supposedly
missing initialization is happening in a different function).
An example is:
https://svn.savannah.gnu.org/viewvc/apl/trunk/src/Shape.hh?view=markup
Shape.hh:133:18: error: ‘shape_Z.Shape::rho[axis]’ may be used
uninitialized in this function [-Werror=maybe-uninitialized]
if (rho[r]) { volume /= rho[r]; rho[r] = sh; volume *=
rho[r]; }
~~~~~^
The line 133 is preceded by an assertion that verifies that rho[r] is
initialized. Apparently the compiler assumes that the initialization
of rho[r] on the right of = happens after the test of rho[r] on the left
of =. It completely ignores, however, the fact that rho[r] was simply
updated and was initialized already before the function (set_shape_item)
was called.
May I kindly request to move this kind of warnings away from -Wall to
-Wextra ?
According to "man g++":
-Wall
This enables all the warnings about constructions that some users
consider questionable, and that are easy to avoid (or modify to
prevent the warning), even in conjunction with macros. This also
In the example above there is no "easy to avoid" way to fix the warning.
Kind regards,
Jürgen Sauermann
Maintainer of GNU APL
