[LLVMbugs] [Bug 11986] Unexpected behavior from -Wswitch-enum

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=11986

David Blaikie <dblaikie at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID

--- Comment #1 from David Blaikie <dblaikie at gmail.com> 2012-02-11 23:06:01 CST ---
Eli - thanks for the heads up on this.

John - I think you /might/ be misunderstanding the behavior of -Wswitch-enum.
To quote the GCC documentation (
http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html ):

-Wswitch
Warn whenever a switch statement has an index of enumerated type and lacks a
case for one or more of the named codes of that enumeration. (The presence of a
default label prevents this warning.) case labels outside the enumeration range
also provoke warnings when this option is used (even if there is a default
label). This warning is enabled by -Wall. 

-Wswitch-enum
Warn whenever a switch statement has an index of enumerated type and lacks a
case for one or more of the named codes of that enumeration. case labels
outside the enumeration range also provoke warnings when this option is used.
>>>The only difference between -Wswitch and this option is that this option
gives a warning about an omitted enumeration code even if there is a default
label.<<< 

To demonstrate this behavior (& Clang's consistency with GCC 4.6.1):

$ cat switch.cpp
enum E { a, b };
int func(E e) {
  switch (e) {
  case a:  return 1;
  }
  return 2;
}
$ clang++ switch.cpp -Wswitch
switch.cpp:3:11: warning: enumeration value 'b' not handled in switch
[-Wswitch]
  switch (e) {
          ^
$ g++ switch.cpp -Wswitch
switch.cpp: In function 'int func(E)':
switch.cpp:3:10: warning: enumeration value 'b' not handled in switch
[-Wswitch]


$ cat switch.cpp
enum E { a, b };
int func(E e) {
  switch (e) {
  case a:  return 1;
  default: return 2;
  }
}
$ clang++ switch.cpp -Wswitch-enum
switch.cpp:3:11: warning: enumeration value 'b' not explicitly handled in
switch [-Wswitch-enum]
  switch (e) {
          ^
$ g++ switch.cpp -Wswitch-enum
switch.cpp: In function âint func(E)â:
switch.cpp:3:10: warning: enumeration value âbâ not handled in switch
[-Wswitch-enum]

(please reopen if I've misunderstood your bug/haven't adequately explained the
behavior/consistency here)

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