clang++: '-Wswitch-enum' turned on by default

Clang Frontend
#1

Hey,

I noticed that clang++ seems to always use the option '-Wswitch-enum'. Shouldn't it be turned off by default? Or is there a way to turn it off?
My projects contain a lot of files. When I compile them with clang++, I get thousands of "Enumeration value 'xxx' not handled in switch" warnings .
I would like to avoid to fix all these warnings. This issue also occurs with Xcode 4.0b3.
I filed the bug 8164.

Thanks,
Alexandre

#2

Hey,

I noticed that clang++ seems to always use the option '-Wswitch-enum'. Shouldn't it be turned off by default?

No, it's an excellent warning to have on by default.

Or is there a way to turn it off?

-Wno-switch-enum

My projects contain a lot of files. When I compile them with clang++, I get thousands of "Enumeration value 'xxx' not handled in switch" warnings .
I would like to avoid to fix all these warnings. This issue also occurs with Xcode 4.0b3.
I filed the bug 8164.

  - Doug

#3

Thanks!

Alexandre

#4

I think that a more serious issue with the warning is that it can produce a ton of noise. In a simple example:

enum x { a, b, c, d, e, f, g };

void foo(enum x a) {
switch (a) {
case b:
case c: break;
}
}

we produce:

t.c:4:11: warning: enumeration value ‘a’ not handled in switch [-Wswitch-enum]
switch (a) {
^
t.c:4:11: warning: enumeration value ‘d’ not handled in switch [-Wswitch-enum]
t.c:4:11: warning: enumeration value ‘e’ not handled in switch [-Wswitch-enum]
t.c:4:11: warning: enumeration value ‘f’ not handled in switch [-Wswitch-enum]
t.c:4:11: warning: enumeration value ‘g’ not handled in switch [-Wswitch-enum]
5 warnings generated.

In this case, I think it would be better to emit one warning say:

t.c:4:11: warning: 5 enumeration values not handled in switch: ‘a’, ‘d’, ‘e’ … [-Wswitch-enum]

or something like that. What do you think?

-Chris

#5

I think that’s an excellent idea.

  • Doug
#6

Done in r114093.

-Chris

#7

That would be a nice improvement. I have some enums with more than 100 elements which cause a lot of warnings.

Alexandre

#8

we produce:

t.c:4:11: warning: enumeration value 'a' not handled in switch [-

Wswitch-enum]

switch (a) {
         ^
t.c:4:11: warning: enumeration value 'd' not handled in switch [-

Wswitch-enum]

t.c:4:11: warning: enumeration value 'e' not handled in switch [-

Wswitch-enum]

t.c:4:11: warning: enumeration value 'f' not handled in switch [-

Wswitch-enum]

t.c:4:11: warning: enumeration value 'g' not handled in switch [-

Wswitch-enum]

5 warnings generated.

In this case, I think it would be better to emit one warning say:

t.c:4:11: warning: 5 enumeration values not handled in switch: 'a', 'd',
'e' ... [-Wswitch-enum]

or something like that. What do you think?

That would be sweet IMHO. Many of the open source libs I use generate
tonnes of noise with this warning, and your proposed change would force
attention on the switch itself and not each little missing case.