1215898 - Fix clang's -Wimplicit-fallthrough warnings in gfx/thebes

Status: RESOLVED FIXED

(Core :: Graphics: Text, defect)

Description

[Chris Peterson [:cpeterson]]

Attachment: MOZ_FALLTHROUGH_gfx-thebes.patch

MOZ_FALLTHROUGH is an annotation to suppress clang's -Wimplicit-fallthrough warnings about switch cases that fall through without a break or return statement. 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;
}

gfx/thebes/gfxContext.cpp:1415:9 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
gfx/thebes/gfxContext.cpp:1419:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
gfx/thebes/gfxFont.cpp:473:9 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
gfx/thebes/gfxFont.cpp:481:9 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
gfx/thebes/gfxFont.cpp:2999:13 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
gfx/thebes/gfxTextRun.cpp:1720:13 [-Wimplicit-fallthrough] unannotated fall-through between switch labels

Comment 1

[Jeff Muizelaar [:jrmuizel]]

Comment on attachment 8675364 [details] [diff] [review]
MOZ_FALLTHROUGH_gfx-thebes.patch

Review of attachment 8675364 [details] [diff] [review]:
-----------------------------------------------------------------

I'm fine with these changes. But it might be worth asking the author of the code in gfxFont.cpp/gfxTextRun.cpp how they feel about the change from using 'default' for NORMAL

Comment 2

[Chris Peterson [:cpeterson]]

Comment on attachment 8675364 [details] [diff] [review]
MOZ_FALLTHROUGH_gfx-thebes.patch

John, do you mind that I created an explicit no-op case for NS_FONT_VARIANT_CAPS_NORMAL (instead of relying on no-op default) and added a MOZ_UNREACHABLE_ASSERT to the default case? I added the assert because the NS_FONT_VARIANT_CAPS values are macros, so the compiler can't report -Wswitch-enum warnings like it could if NS_FONT_VARIANT_CAPS was an enum.

https://mxr.mozilla.org/mozilla-central/source/gfx/thebes/gfxFontConstants.h#78

Comment 3

[John Daggett (:jtd)]

Comment on attachment 8675364 [details] [diff] [review]
MOZ_FALLTHROUGH_gfx-thebes.patch

Review of attachment 8675364 [details] [diff] [review]:
-----------------------------------------------------------------

Sure, looks reasonable.

Comment 4

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/e83fc4b17ab5

Comment 5

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/e83fc4b17ab5

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/releases/mozilla-b2g44_v2_5/rev/e83fc4b17ab5

Comment 7

[Carsten Book [:Tomcat]]

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