1220035 - Fix -Wimplicit-fallthrough warnings in xpcom

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Chris Peterson [:cpeterson]]

Attachment: Wimplicit-fallthrough_xpcom.patch

Suppress clang's -Wimplicit-fallthrough warnings (not yet enabled by default in mozilla-central) about switch cases that fall through without a break or return statement. The warnings can be suppressed with the MOZ_FALLTHROUGH, a MFBT macro for a clang compiler annotation. MOZ_FALLTHROUGH is only needed on cases that have code:

switch (foo) {
  case 1: // These cases have no code. No fallthrough annotations are needed.
  case 2:
  case 3:
    foo = 4; // This case has code, so a fallthrough annotation is needed:
    MOZ_FALLTHROUGH;
  default:
    return foo;
}

xpcom/base/nsDebugImpl.cpp:458:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/ds/nsCheapSets.h:139:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/ds/nsPersistentProperties.cpp:232:9 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/ds/nsVariant.cpp:360:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/ds/nsVariant.cpp:766:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/ds/nsVariant.cpp:1658:9 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/ds/nsVariant.cpp:1661:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/glue/nsTextFormatter.cpp:355:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/glue/nsTextFormatter.cpp:362:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/io/nsWildCard.cpp:85:7 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
xpcom/io/nsWildCard.cpp:401:7 [-Wimplicit-fallthrough] unannotated fall-through between switch labels

Comment 1

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c8488e4be05d

Comment 2

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/c8488e4be05d

Comment 3

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/releases/mozilla-b2g44_v2_5/rev/c8488e4be05d

Comment 4

[Carsten Book [:Tomcat]]

removing the b2g 2.5 flag since this commit has been reverted due to an incorrect merge, sorry for the confusion