On Tue, 1 Jan 2019, Martok wrote:
Hi all,
The attached patch adds two messages inspired by C compiler's -Wswitch-enum and
-Wcovered-switch-default. Building on the recent label count refactoring, this
was fairly straightforward.
- If a case statement on an ordinal does not contain labels for all values of
the ordinal, and no else statement is given, raise a new warning (W6059). This
is actually defined as an error in ISO7185 and a dynamic-violation in IEC10206.
- If a case statement has labels for the entire range of the type, and an (now
never used) else statement is present, a warning "Unreachable code" is raised.
Both cases are clearly something where the compiler and programmer don't agree
on something, hence drawing attention to these situations.
The checks are enabled only for enumerated types and small (1-byte) integers. In
C, they are only for enumerated types, I added small types because they are
often used as tag types, where this check is extra useful.
Now, the RFC part. I have a few open questions...
* does it make sense to do that to all integral types? In ISO mode, it's
formally required for all case statements. I left it out for now as sometimes
case..of is used as a shorthand for multiple in..[range], there would be more
detections that look like false positives.
It does not make sense. Consider the following:
Type
TMyClass = class
Private
function GetString(AIndex: Integer): string;
Published
Property MyString : String Index 1 Read GetString;
end;
function TMyClass.GetString(AIndex: Integer): string;
begin
case AIndex of
1 : Result:=GenerateSomestringvalue;
end;
end;
I don't think there should be errors or warnings.
Michael.
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