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Diffstat (limited to 'gcc/ada/par.adb')
| -rw-r--r-- | gcc/ada/par.adb | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/gcc/ada/par.adb b/gcc/ada/par.adb index 6788692..7e69166d 100644 --- a/gcc/ada/par.adb +++ b/gcc/ada/par.adb @@ -535,6 +535,66 @@ function Par (Configuration_Pragmas : Boolean) return List_Id is Table_Increment => 100, Table_Name => "Scope"); + ------------------------------------------ + -- Table for Handling Suspicious Labels -- + ------------------------------------------ + + -- This is a special data structure which is used to deal very spefifically + -- with the following error case + + -- label; + -- loop + -- ... + -- end loop label; + + -- Similar cases apply to FOR, WHILE, DECLARE, or BEGIN + + -- In each case the opening line looks like a procedure call because of + -- the semicolon. And the end line looks illegal because of an unexpected + -- label. If we did nothing special, we would just diagnose the label on + -- the end as unexpected. But that does not help point to the real error + -- which is that the semicolon after label should be a colon. + + -- To deal with this, we build an entry in the Suspicious_Labels table + -- whenever we encounter an identifier followed by a semicolon, followed + -- by one of LOOP, FOR, WHILE, DECLARE, BEGIN. Then this entry is used to + -- issue the right message when we hit the END that confirms that this was + -- a bad label. + + type Suspicious_Label_Entry is record + Proc_Call : Node_Id; + -- Node for the procedure call statement built for the label; construct + + Semicolon_Loc : Source_Ptr; + -- Location of the possibly wrong semicolon + + Start_Token : Source_Ptr; + -- Source location of the LOOP, FOR, WHILE, DECLARE, BEGIN token + end record; + + package Suspicious_Labels is new Table.Table ( + Table_Component_Type => Suspicious_Label_Entry, + Table_Index_Type => Int, + Table_Low_Bound => 1, + Table_Initial => 50, + Table_Increment => 100, + Table_Name => "Suspicious_Labels"); + + -- Now when we are about to issue a message complaining about an END label + -- that should not be there because it appears to end a construct that has + -- no label, we first search the suspicious labels table entry, using the + -- source location stored in the scope table as a key. If we find a match, + -- then we check that the label on the end matches the name in the call, + -- and if so, we issue a message saying the semicolon should be a colon. + + -- Quite a bit of work, but really helpful in the case where it helps, and + -- the need for this is based on actual experience with tracking down this + -- kind of error (the eye often easily mistakes semicolon for colon!) + + -- Note: we actually have enough information to patch up the tree, but + -- this may not be worth the effort! Also we could deal with the same + -- situation for EXIT with a label, but for now don't bother with that! + --------------------------------- -- Parsing Routines by Chapter -- --------------------------------- |