[cfe-commits] r148640 - in /cfe/trunk: include/clang/Basic/DiagnosticGroups.td include/clang/Basic/DiagnosticSemaKinds.td lib/Sema/SemaStmt.cpp test/Sema/switch.c test/Sema/warn-unreachable.c test/SemaCXX/gnu-case-ranges.cpp test/SemaCXX/return-noreturn.cpp

[Richard Smith]

On Sat, January 21, 2012 18:12, David Blaikie wrote:
> Author: dblaikie
> Date: Sat Jan 21 12:12:07 2012
> New Revision: 148640
>
>
> URL: http://llvm.org/viewvc/llvm-project?rev=148640&view=rev
> Log:
> Add -Wswitch-enum-redundant-default.
>
>
> This warning acts as the complement to the main -Wswitch-enum warning (which
> warns whenever a switch over enum without a default doesn't cover all values
> of the enum) & has been an an-doc coding convention in LLVM and Clang in my
> experience. The purpose is to ensure there's never a "dead" default in a
> switch-over-enum because this would hide future -Wswitch-enum errors.
>
> The name warning has a separate flag name so it can be disabled but it's
> grouped under -Wswitch-enum & is on-by-default because of this.
>
> The existing violations of this rule in test cases have had the warning
> disabled & I've added a specific test for the new behavior (many negative
> cases already exist in the same test file - and none regressed - so I didn't
> add more).
>
> Reviewed by Ted Kremenek (
> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20120116/051690.ht
> ml )
>
> Modified:
> cfe/trunk/include/clang/Basic/DiagnosticGroups.td
> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> cfe/trunk/lib/Sema/SemaStmt.cpp cfe/trunk/test/Sema/switch.c
> cfe/trunk/test/Sema/warn-unreachable.c
> cfe/trunk/test/SemaCXX/gnu-case-ranges.cpp
> cfe/trunk/test/SemaCXX/return-noreturn.cpp
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticS
> emaKinds.td?rev=148640&r1=148639&r2=148640&view=diff
> =============================================================================
> =
> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Sat Jan 21 12:12:07
> 2012
> @@ -4946,19 +4946,22 @@
> def warn_missing_case_for_condition : Warning<"no case matching constant switch
> condition '%0'">; def warn_missing_case1 : Warning<"enumeration value %0 not
> handled in switch">, -  InGroup<DiagGroup<"switch-enum"> >;
> +  InGroup<SwitchEnum>;
> def warn_missing_case2 : Warning< "enumeration values %0 and %1 not handled in
> switch">, -  InGroup<DiagGroup<"switch-enum"> >;
> +  InGroup<SwitchEnum>;
> def warn_missing_case3 : Warning< "enumeration values %0, %1, and %2 not
> handled in switch">, -  InGroup<DiagGroup<"switch-enum"> >;
> +  InGroup<SwitchEnum>;
> def warn_missing_cases : Warning< "%0 enumeration values not handled in switch:
> %1, %2, %3...">,
> -  InGroup<DiagGroup<"switch-enum"> >;
> +  InGroup<SwitchEnum>;
> +def warn_unreachable_default : Warning<
> +  "default is unreachable as all enumeration values are accounted for">,

This diagnostic is not technically correct; an expression of enumeration type
can have a value which is not a named member of that enumeration. How about
something like 'default label in switch which covers all enumeration values'?
For the same reason, I'm slightly hesitant about the name of this warning
flag.

- Richard