CODEWITHSUNDEEP
concurrencysyntax-errortaskada
ArekBulski
ArekBulski

Reputation: 5098

Ada object "Train" cannot be used before end of its declaration

What is the problem with this code? Compiler says two things, that there is no Run entry and that Run accept does not match an entry (both seem wrong), and separately that Train cannot be used before declaration (but it is already declared). Please explain to me what is going on.

I am hesitant to show entire code but can do so.

type ItineraryType is array (0..255) of Integer;
type Train is record
    Label : Integer;
    Capacity : Integer;
    Maxspeed : Integer;
    Starts : Integer;
    Itinerary : ItineraryType;
    Stops : Integer;
    lock : access Mutex;
end record;

task type TrainThread is
    entry Run (train1:Train);
end;
task body TrainThread is
    train : Train;
begin
    accept Run (train1:Train) do
        train := train1;
    end;
end;

-- part of main
train1 := new TrainThread;
train1.Run(trains(i));

main.adb:51:05: warning: no accept for entry "Run"
main.adb:52:17: object "Train" cannot be used before end of its declaration
main.adb:54:09: no entry declaration matches accept statement
gnatmake: "main.adb" compilation error

Upvotes: 3

Views: 2203

Answers (1)

raph.amiard
raph.amiard

Reputation: 2785

Ada is case insensitive, so train and Train are equivalent. So the declaration train : Train will always be invalid. (Admittedly gnat's message could be better in this case)

Upvotes: 6

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