[PATCH] libcamera: base: log: Fix uninitialized variable warning

[Kieran Bingham]

Quoting Laurent Pinchart (2025-03-03 10:48:29)
> On Mon, Mar 03, 2025 at 11:41:58AM +0100, Barnabás Pőcze wrote:
> > 2025. március 2., vasárnap 3:09 keltezéssel, Laurent Pinchart írta:
> > 
> > > gcc 13.3.0, cross-compiling from amd64 to arm64, warns about a possibly
> > > uninitialized variable in Logger::parseLogLevel():
> > 
> > Yet it has no problems with it when not cross compiling:
> > https://gitlab.freedesktop.org/camera/libcamera/-/jobs/71959259 ...
> > 
> > > 
> > > src/libcamera/base/log.cpp: In static member function ‘static libcamera::LogSeverity libcamera::Logger::parseLogLevel(std::string_view)’:
> > > ../../src/libcamera/base/log.cpp:694:55: error: ‘severity’ may be used uninitialized [-Werror=maybe-uninitialized]
> > >   694 |                 if (ec != std::errc() || *end != '\0' || severity > LogFatal)
> > >       |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
> > > src/libcamera/base/log.cpp:690:22: note: ‘severity’ was declared here
> > >   690 |         unsigned int severity;
> > >       |                      ^~~~~~~~
> > > 
> > > This appears to be a false positive, as the std::from_chars() function
> > > should set severity value when it returns without an error. Still, the
> > > warning is easy to solve, so fix it by initializing the severity
> > > variable.
> > 
> > I am pretty sure it is false positive, barring any bugs in from_chars(), unfortunate...
> 
> I'm pretty sure as well, but I don't really see an alternative to this
> patch for the time being.
> 
> > > Fixes: 8fa119e0b50f ("libcamera: base: log: Use `std::from_chars()`")
> > > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > > ---
> > >  src/libcamera/base/log.cpp | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > 
> > > diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp
> > > index 6a040b59290a..8bf3e1daa9c6 100644
> > > --- a/src/libcamera/base/log.cpp
> > > +++ b/src/libcamera/base/log.cpp
> > > @@ -687,14 +687,13 @@ LogSeverity Logger::parseLogLevel(std::string_view level)
> > >             "FATAL",
> > >     };
> > > 
> > > -   unsigned int severity;
> > > +   unsigned int severity = LogInvalid;

False positive or not, it's not /incorrect/ to initialise the variable -
so if it's a solution it's fine with me.


Acked-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> > > 
> > >     if (std::isdigit(level[0])) {
> > >             auto [end, ec] = std::from_chars(level.data(), level.data() + level.size(), severity);
> > >             if (ec != std::errc() || *end != '\0' || severity > LogFatal)
> > >                     severity = LogInvalid;
> > >     } else {
> > > -           severity = LogInvalid;
> > >             for (unsigned int i = 0; i < std::size(names); ++i) {
> > >                     if (names[i] == level) {
> > >                             severity = i;
> > > 
> > > base-commit: c0a58b97989f7d529f1469b2c2f8705ff55d3af4
> 
> -- 
> Regards,
> 
> Laurent Pinchart