Am 24.05.22 um 19:28 schrieb Thomas Kurz via fpc-pascal:
Dear all,please consider the following code: program Project1; {$booleval off} var v1, v2: variant; a: boolean; b: integer; begin a := true; b := 0; // this works as expected: if a and (b > 0) and ((0+1) mod b = 0) then Writeln ('ok'); v1 := true; v2 := 0; // this gives a "division by zero": if v1 and (v2 > 0) and ((0+1) mod v2 = 0) then Writeln ('ok'); end. The "variant" variant results in a "division by zero". Obviously, it tries to evaluate the modulo-expression even though this shouldn't happen because complete boolean evaluation is disabled and the "if"-result is already known to be false after checking "v2>0". Can anyone explain this strange behavior?
When compiling the and expressions, the compiler does not know (in this example it could, but in general it cannot) what the variants contain so just the variant and-operator is executed which does not/cannot distinguish between the logical and bitwise and variant.
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