Re: [PATCH] configure: Disable -Wtautological-type-limit-compare

[Eric Blake]

On 6/5/20 1:09 PM, Peter Maydell wrote:

> If there's an ordering requirement here we should make it clearer,
> or somebody is going to do the obvious "tidying up" at some point
> in the future.
>
> Perhaps this whole set of lines should be rearranged, something like:
>
> # Enable these warnings if the compiler supports them:
> warn_flags="-Wold-style-declaration -Wold-style-definition -Wtype-limits"
> warn_flags="-Wformat-security -Wformat-y2k -Winit-self
> -Wignored-qualifiers $warn_flags"
> warn_flags="-Wno-missing-include-dirs -Wempty-body -Wnested-externs $warn_flags"
> warn_flags="-Wendif-labels -Wexpansion-to-defined $warn_flags"
> # Now disable sub-types of warning we don't want but which are
> # enabled by some of the warning flags we do want; these must come
> # later in the compiler command line than the enabling warning options.
> nowarn_flags="-Wno-missing-include-dirs -Wno-shift-negative-value"
> nowarn_flags="-Wno-initializer-overrides $nowarn_flags"
> nowarn_flags="-Wno-string-plus-int -Wno-typedef-redefinition $nowarn_flags"
> warn_flags="$warn_flags $nowarn_flags"
>
> (is there a nicer shell idiom for creating a variable that's
> a long string of stuff without having over-long lines?)

You could always do:

# Append $2 into the variable named $1, with space separation
add_to () {
    eval $1=\${$1:+\"\$$1 \"}\$2
}

add_to warn_flags -Wold-style-declaration
add_to warn_flags -Wold-style-definition
add_to warn_flags -Wtype-limits
...
add_to nowarn_flags -Wno-string-plus-int
add_to nowarn_flags -Wno-typedef-redefinition
warn_flags="$warn_flags $nowarn_flags"

> It's also tempting to pull the handful of warning related
> options currently set directly in QEMU_CFLAGS (-Wall, etc) into
> this same set of variables.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org