[fpc-pascal] Very odd case parsing problem

Mark Morgan Lloyd markMLl.fpc-pascal at telemetry.co.uk
Sat Dec 28 21:47:23 CET 2013

I've been wrestling with something for a chunk of the early evening, 
which is reproducible in situ but not in a cut-down test program.

Using 2.6.2 on x86 Linux in objfpc mode, a case statement that looks 
like this fails to parse:

     case parseCommand(selector) of
       help:        begin
       help_:       begin
       quit_:       if High(lexemeListArray) = 1 then begin
     end // line 323

As it stands, compilation fails with

centralcontrol/distributionanddisplay.pas(323,5) Error: Constant and 
CASE types do not match
centralcontrol/distributionanddisplay.pas(323,5) Error: Constant 
Expression expected
centralcontrol/distributionanddisplay.pas(323,5) Error: duplicate case label
centralcontrol/distributionanddisplay.pas(323,5) Fatal: Syntax error, 
":" expected but "END" found

I can fix that either by putting a semicolon before the else- which I 
believe is strictly incorrect- or by putting begin/end around that 
conditional, or by inserting a dummy statement before the else like

       quit_:       if High(lexemeListArray) = 1 then begin
       nop:         begin end

I suspect I might have seen this happen before, but it's not an easy one 
to grep for. Does this make sense to anybody, is it a known (and 
preferably fixed) issue, or should I be putting time into trying to 
match the behaviour in a cut-down test program?

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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