W1037 FOR-Loop variable '%s' may be undefined after loop (Delphi)
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This warning is issued if the value of a for loop control variable is used after the loop.
You can only rely on the final value of a for loop control variable if the loop is left with a goto or exit statement.
The purpose of this restriction is to enable the compiler to generate efficient code for the for loop.
program Produce; (*$WARNINGS ON*) function Test1: Integer; var I: Byte; begin Result := 0; for I := 0 to 255 do Inc(Result); WriteLn(I); // undefined end; begin Test1; end.
In the example, the control variable is used implicitly after the loop, so that it may be undefined - hence the warning.