Hard exhaustiveness instance in C#

test.cs

class Test {
    int f(int x0, int x1, int x2, int x3, int x4, int x5, int x6, int x7, int x8, int x9) {
        return (x0, x1, x2, x3, x4, x5, x6, x7, x8, x9) switch {
            (>= 78, >= 80, >= 83, >= 62, < 90, >= 32, < 84, < 77, >= 51, >= 8) => 0,
            (< 64, >= 85, >= 7, < 98, >= 71, < 26, >= 37, >= 34, < 5, < 39) => 1,
            (>= 23, >= 56, >= 36, >= 64, < 27, < 72, >= 67, >= 28, >= 93, >= 73) => 2,
            (>= 35, < 27, >= 71, >= 79, < 95, < 11, >= 86, < 32, < 32, >= 78) => 3,
            (< 86, >= 83, < 90, < 99, < 35, < 6, < 69, < 80, < 4, < 85) => 4,
            (< 38, >= 77, >= 70, >= 0, >= 9, < 96, < 5, < 39, >= 20, < 25) => 5,
            (< 46, >= 71, >= 74, < 2, < 79, < 56, >= 34, < 8, < 53, >= 36) => 6,
            (< 55, >= 99, >= 10, >= 6, < 36, < 2, < 22, < 29, < 0, >= 80) => 7,
            (< 16, < 43, < 79, < 68, >= 53, < 57, >= 35, < 21, < 98, < 15) => 8,
            (>= 90, < 62, < 60, >= 39, < 34, >= 40, < 23, < 42, < 92, >= 19) => 9,
            (>= 18, < 32, < 39, >= 94, < 89, < 95, < 70, >= 90, >= 28, < 58) => 10,
            (< 61, < 57, >= 95, < 4, >= 98, >= 34, >= 40, >= 59, < 55, >= 56) => 11,
            (>= 2, >= 34, < 5, < 58, < 19, < 44, < 95, >= 70, < 60, >= 17) => 12,
            (>= 89, < 49, < 42, < 23, < 39, < 3, >= 48, >= 65, < 48, < 64) => 13,
            (>= 15, >= 26, < 31, < 88, >= 58, < 35, < 4, < 84, >= 36, >= 71) => 14,
            (>= 91, >= 76, < 38, >= 46, < 74, < 55, < 19, >= 33, < 13, < 43) => 15,
            (< 85, < 72, < 77, < 60, < 57, < 75, < 25, < 37, >= 66, >= 0) => 16,
            (< 63, < 66, >= 49, < 5, < 46, >= 81, >= 6, < 69, >= 68, >= 99) => 17,
            (< 42, >= 10, < 97, >= 30, < 8, < 31, < 49, < 16, < 88, < 23) => 18,
            (< 69, < 89, >= 69, >= 16, >= 41, < 76, >= 43, >= 99, < 84, < 76) => 19,
            (< 97, >= 48, < 0, >= 18, >= 17, < 36, < 56, < 91, < 61, < 47) => 20,
            (< 58, >= 65, >= 40, < 48, < 87, < 46, < 74, < 48, >= 79, < 75) => 21,
            (< 27, < 29, < 52, >= 28, >= 31, >= 20, >= 54, < 10, < 70, >= 70) => 22,
            (< 31, < 61, < 75, >= 33, >= 84, < 66, >= 94, < 2, >= 65, < 72) => 23,
            (< 77, >= 64, >= 46, < 45, < 6, >= 79, >= 26, < 81, >= 94, >= 29) => 24,
            (>= 29, < 54, < 25, >= 27, < 15, >= 19, >= 17, >= 73, >= 8, < 69) => 25,
            (>= 26, < 88, >= 35, < 72, < 86, >= 89, >= 60, < 79, >= 81, >= 22) => 26,
            (>= 1, >= 47, < 19, < 63, >= 97, < 70, >= 89, >= 82, < 12, >= 63) => 27,
            (< 98, < 5, >= 22, < 40, >= 42, < 50, >= 12, >= 89, < 43, >= 9) => 28,
            (>= 30, < 74, < 37, < 11, >= 20, < 71, < 99, < 23, >= 83, >= 87) => 29,
            (>= 53, >= 67, < 93, >= 10, >= 1, >= 68, < 46, >= 49, < 34, < 74) => 30,
            (< 95, < 94, >= 94, >= 78, >= 61, < 12, >= 64, >= 27, >= 29, >= 93) => 31,
            (>= 3, < 90, >= 58, < 8, < 83, >= 45, < 63, >= 95, < 58, >= 28) => 32,
            (< 19, >= 98, >= 82, >= 57, >= 40, >= 94, >= 72, < 36, < 31, >= 49) => 33,
            (< 33, >= 40, < 98, < 31, >= 25, >= 47, < 9, < 78, >= 40, >= 66) => 34,
            (< 94, < 8, < 80, < 32, >= 7, < 86, >= 79, >= 53, < 89, >= 44) => 35,
            (>= 5, >= 22, < 6, >= 59, >= 78, >= 28, < 36, >= 22, < 33, >= 20) => 36,
            (>= 81, >= 41, < 84, < 67, < 11, < 85, >= 78, < 25, >= 50, >= 11) => 37,
            (>= 51, >= 46, < 15, >= 61, < 88, < 43, >= 3, < 30, < 14, < 55) => 38,
            (>= 17, >= 39, >= 3, < 29, >= 52, < 82, >= 20, >= 6, >= 47, >= 61) => 39,
            (>= 44, >= 1, < 91, < 95, >= 56, >= 93, >= 53, >= 60, < 73, < 65) => 40,
            (>= 10, < 73, < 78, >= 41, >= 29, >= 99, < 93, < 57, >= 99, >= 14) => 41,
            (>= 47, < 63, >= 67, >= 74, < 48, < 78, < 16, >= 44, >= 54, >= 88) => 42,
            (>= 41, >= 2, < 54, >= 12, >= 30, >= 49, < 52, >= 20, >= 85, < 5) => 43,
            (>= 40, < 79, >= 72, < 55, < 50, < 80, < 97, < 12, < 24, >= 48) => 44,
            (< 93, < 45, < 63, < 20, < 69, >= 9, < 7, >= 14, < 17, >= 57) => 45,
            (< 80, >= 21, >= 2, >= 86, < 91, >= 91, < 32, >= 76, < 44, >= 83) => 46,
            (>= 54, >= 16, >= 86, >= 43, >= 93, >= 88, >= 73, < 58, < 74, < 94) => 47,
            (< 37, >= 44, < 4, < 38, >= 68, < 69, < 77, < 96, < 2, >= 41) => 48,
            (< 92, >= 87, < 26, >= 93, >= 60, < 53, < 14, >= 18, >= 25, < 34) => 49,
            (>= 84, >= 7, < 27, < 24, >= 13, >= 16, >= 85, < 86, < 23, < 98) => 50,
            (>= 50, >= 78, >= 20, >= 15, < 66, < 4, < 58, < 4, < 78, < 90) => 51,
            (< 0, >= 58, >= 34, < 84, >= 16, < 23, < 88, >= 47, >= 18, >= 13) => 52,
            (>= 70, < 20, >= 48, >= 65, < 45, >= 13, >= 76, < 31, >= 30, < 4) => 53,
            (< 72, >= 13, < 12, >= 50, < 62, >= 51, < 10, < 97, < 86, < 81) => 54,
            (>= 39, >= 95, >= 88, >= 21, < 73, >= 64, >= 66, < 38, >= 67, < 35) => 55,
            (< 76, < 38, < 28, >= 89, < 38, < 67, < 80, < 19, >= 96, >= 46) => 56,
            (< 21, >= 14, >= 55, < 47, < 43, >= 14, >= 27, >= 66, >= 82, >= 33) => 57,
            (>= 43, < 11, < 85, < 42, >= 72, >= 24, >= 92, >= 41, >= 49, < 60) => 58,
            (>= 59, >= 23, < 11, >= 70, >= 21, < 0, < 2, < 85, >= 27, < 6) => 59,
            (>= 88, < 75, >= 9, < 80, < 51, >= 7, >= 33, >= 93, < 69, >= 7) => 60,
            (< 67, >= 15, >= 53, >= 97, < 92, >= 87, >= 18, < 9, < 75, >= 27) => 61,
            (>= 87, >= 25, < 73, < 56, < 37, >= 63, < 13, >= 92, >= 37, >= 91) => 62,
            (>= 36, >= 33, >= 24, < 19, >= 5, < 60, < 61, >= 40, < 39, < 31) => 63,
            (>= 20, < 84, >= 81, < 44, >= 67, >= 84, >= 41, < 17, >= 10, >= 97) => 64,
            (>= 79, < 18, < 17, < 69, < 18, < 73, >= 28, >= 51, >= 97, >= 92) => 65,
            (>= 11, >= 50, >= 45, < 25, < 44, < 59, < 62, >= 94, >= 87, < 2) => 66,
            (>= 57, < 36, >= 18, >= 85, < 49, >= 22, >= 68, >= 75, < 56, < 51) => 67,
            (>= 52, < 82, >= 41, < 35, >= 47, < 61, >= 57, >= 64, >= 16, >= 79) => 68,
            (< 49, >= 52, < 1, >= 73, >= 4, >= 21, < 55, >= 98, >= 21, >= 82) => 69,
            (>= 75, < 9, < 89, < 96, < 65, < 30, < 31, < 5, < 26, >= 26) => 70,
            (>= 60, < 30, >= 32, >= 26, < 23, >= 1, < 98, >= 13, >= 77, >= 30) => 71,
            (>= 13, >= 68, < 66, >= 92, < 10, >= 83, < 29, < 61, >= 1, >= 32) => 72,
            (>= 9, >= 96, >= 47, < 53, < 76, >= 33, < 75, >= 62, >= 95, >= 96) => 73,
            (< 12, >= 81, >= 68, >= 87, >= 94, < 98, < 21, >= 88, >= 42, >= 50) => 74,
            (>= 99, < 0, < 92, >= 37, >= 64, < 54, >= 59, >= 67, >= 19, >= 21) => 75,
            (>= 82, >= 59, >= 23, < 54, >= 32, >= 42, >= 51, >= 74, < 6, < 84) => 76,
            (< 6, >= 19, >= 96, < 22, >= 77, < 17, >= 83, >= 83, >= 15, < 24) => 77,
            (>= 4, < 4, < 33, < 91, < 85, >= 37, < 47, >= 68, < 45, >= 16) => 78,
            (< 7, < 3, < 16, >= 49, >= 99, >= 41, < 65, < 0, < 52, < 12) => 79,
            (< 74, >= 70, < 50, >= 90, >= 28, >= 65, >= 71, < 43, >= 62, >= 38) => 80,
            (< 73, < 31, >= 61, >= 71, >= 12, < 25, >= 87, >= 50, < 38, >= 86) => 81,
            (< 56, < 69, >= 99, < 1, < 54, < 38, >= 90, >= 52, >= 22, >= 37) => 82,
            (< 28, >= 55, >= 64, < 83, >= 55, < 10, < 50, >= 45, >= 9, >= 42) => 83,
            (< 14, >= 6, < 51, < 14, < 63, < 74, < 45, < 3, < 91, >= 95) => 84,
            (>= 8, < 93, >= 62, < 9, >= 75, >= 92, < 44, >= 63, >= 72, >= 53) => 85,
            (>= 62, < 91, < 29, < 76, >= 3, < 39, >= 30, >= 54, >= 64, < 89) => 86,
            (>= 34, >= 42, < 65, < 13, < 70, < 90, < 15, >= 15, < 46, >= 67) => 87,
            (>= 83, < 37, < 87, >= 81, < 26, < 97, < 82, >= 71, < 76, < 10) => 88,
            (< 96, < 35, < 56, < 77, < 0, < 8, < 81, >= 26, < 11, >= 18) => 89,
            (< 32, >= 97, >= 76, >= 51, >= 2, >= 15, < 42, < 55, < 7, < 45) => 90,
            (< 68, >= 60, >= 57, >= 36, >= 80, < 58, < 0, < 24, >= 57, < 40) => 91,
            (< 24, < 24, < 13, < 7, >= 22, >= 62, < 39, >= 1, < 90, < 62) => 92,
            (< 71, < 92, < 43, >= 82, >= 14, < 18, >= 24, < 72, >= 3, >= 59) => 93,
            (< 22, >= 17, < 8, < 52, >= 96, < 52, >= 1, >= 35, >= 71, >= 1) => 94,
            (>= 45, >= 86, >= 59, < 3, < 59, < 77, >= 38, >= 56, >= 35, < 77) => 95,
            (>= 25, >= 12, < 44, < 66, < 81, >= 5, >= 8, < 46, >= 63, < 52) => 96,
            (>= 66, >= 28, < 14, >= 17, < 82, >= 29, >= 96, >= 11, < 80, < 54) => 97,
            (< 48, < 53, >= 30, < 34, < 33, >= 27, >= 91, < 7, < 41, < 68) => 98,
            (>= 65, >= 51, >= 21, >= 75, >= 24, < 48, >= 11, >= 87, < 59, >= 3) => 99,
        };
    }
}

I was using sharplab.io to test it (which just hangs). I'll double-check with a recent command line-line compiler.

See dotnet/roslyn#56230 (comment) for a program that produces moderate-sized C# pattern-matching instances that are quite hard.

Thanks! Good one.