Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
The warnings configuration we use in the PSPDFKit iOS framework - http://pspdfkit.com
//
// Warnings.xcconfig
//
// The list of warnings we (don’t) use, and the reasons why.
//
// :MARK: Warnings in use:
// :MARK: -everything
// We want the best possible diagnostics, so we simply enable everything that exists, and then opt–out of what doesn’t make sense for us.
//
// :MARK: - Warnings not to be promoted:
// Even if a project sets ``-Werror``, the following shall not be promoted to errors:
// :MARK: -deprecated-declarations
// Even if some API is deprecated, we may still need to call it for compatibility reasons.
// Thus, we cannot allow this warning to become promoted to an error.
// :MARK: -deprecated-implementations
// Deprecations are necessary, and useful to signal (pending) API changes.
// For compatibility reasons, it may still be necessary to implement, and even override those methods, though.
//
// :MARK: - Warnings that have been disabled:
// :MARK: -objc-missing-property-synthesis
// This isn’t a real issue since we don’t have any interest in building on extremely old Clangs.
// (Also, each property that cannot be auto–synthesized triggers at least a warning…)
// :MARK: -unused-parameter
// While this is generally desirable to prevent a subvariaty of typo–bugs, enabling this warning now would mean **a lot** of noise. => Disabled for now.
// :MARK: -covered-switch-default
// This would emit a warning for every use of a default label, however since C can't guarantee that an integer type used as enum *only* contains valid enum values, we need default labels.
// :MARK: -direct-ivar-access
// This is a mid-term project. We currently use a lot of direct ivar access. Sometimes explicitely, sometimes just because there's code from iOS 4 where dispatch types were not yet objects, or because there's mixed code style in it.
// TODO: Why, actually? To much noise?
// :MARK: -assign-enum
// Disabling this would require casting enum option values instead of using 0 to indicate not special setting.
// For example: (NSEnumerationOptions)kNilOptions (since there is no NSEnumerationOptionNone)
// Where bit masks are used, a cast would be required in any case (UIViewAnimationOptions
// :MARK: -float-equal
// While we could change all 90 instances of floating point comparison to a method that includes an epsilon, this is overkill and not needed.
// See http://stackoverflow.com/questions/11421756/weverything-yielding-comparing-floating-point-with-or-is-unsafe
// :MARK: -vla
// Variable length arrays are a feature of C99 and used in some places.
// There's no reason to disallow this useful feature, when used in moderation. It also works with C++:
// http://clang.llvm.org/compatibility.html#vla
// :MARK: -pedantic
// Too. Much. Noise.
// :MARK: -documentation-unknown-command
// Even though Xcode correctly highlights certain documentation directives, (like e.g. `@throws`) it does not seem to know them internally.
// Since these annotations are still useful, we don’t want them to become warnings.
// :MARK: -packed
// Disabling this warning appears to be necessary because of a bug reported against Clang in late 2013 (http://llvm.org/bugs/show_bug.cgi?id=18132).
// It only triggers in Vendor/lz4.c, but since the flag is defective there’s no point in enabling it.
// :MARK: -padded
// This isn’t really an issue to us, since we’re not programming embedded systems.
// :MARK: -auto-import
// Standard ``import`` is used by tons of files we import ourselves. => Disabled.
// :MARK: -selector
// This warning requires that a selector with the name passed into `@selector()` is implemented in that same translation unit.
// Which is counter to the primary use case for that construct: `respondsToSelector:` checks.
// :MARK: -receiver-is-weak
// This needs some thorough discussion, and thinking through:
// As far as I know, sending a message to a weak receiver — just as any access to a weak variable — causes the compiler to emit a call to `objc_storeStrong()` call, that prevents the situation being warned against here.
// It may however be the case that the compiler can remove this call during optimization under certain conditions, which _could_ then lead to the receiver actually becoming `nil` due to some sort of race–condition, because the last strong reference to this object is being released on another thread, which — in turn — would cause the story–book example of a Heisenbug.
// :MARK: -sign-conversion
// There are a couple of extremely subtle bugs that lure behind this warning, but most of these are very unlikely to happen.
// Given that there’s a ton of code that uses NSIndexPath, and implements <UITableViewDataSource> which unfortunately use signed integers as parameters/return–values for API that uses unsigned integers, this is simply too much noise.
WARNING_CFLAGS = -Weverything -Wno-error-deprecated-declarations -Wno-error-deprecated-implementations -Wno-objc-missing-property-synthesis -Wno-unused-parameter -Wno-covered-switch-default -Wno-direct-ivar-access -Wno-assign-enum -Wno-float-equal -Wno-vla -Wno-pedantic -Wno-documentation-unknown-command -Wno-packed -Wno-padded -Wno-auto-import -Wno-selector -Wno-receiver-is-weak -Wno-sign-conversion
@steipete

This comment has been minimized.

Copy link
Owner Author

@steipete steipete commented Sep 29, 2014

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.