   LL|       |#![feature(coverage_attribute)]
   LL|       |//@ edition: 2021
   LL|       |//@ compile-flags: -Zcoverage-options=mcdc
   LL|       |//@ llvm-cov-flags: --show-branches=count --show-mcdc
   LL|       |
   LL|      2|fn mcdc_check_neither(a: bool, b: bool) {
   LL|      2|    if a && b {
                          ^0
  ------------------
  |  Branch (LL:8): [True: 0, False: 2]
  |  Branch (LL:13): [True: 0, False: 0]
  ------------------
  |---> MC/DC Decision Region (LL:8) to (LL:14)
  |
  |  Number of Conditions: 2
  |     Condition C1 --> (LL:8)
  |     Condition C2 --> (LL:13)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2    Result
  |  1 { F,  -  = F      }
  |
  |  C1-Pair: not covered
  |  C2-Pair: not covered
  |  MC/DC Coverage for Decision: 0.00%
  |
  ------------------
   LL|      0|        say("a and b");
   LL|      2|    } else {
   LL|      2|        say("not both");
   LL|      2|    }
   LL|      2|}
   LL|       |
   LL|      2|fn mcdc_check_a(a: bool, b: bool) {
   LL|      2|    if a && b {
                          ^1
  ------------------
  |  Branch (LL:8): [True: 1, False: 1]
  |  Branch (LL:13): [True: 1, False: 0]
  ------------------
  |---> MC/DC Decision Region (LL:8) to (LL:14)
  |
  |  Number of Conditions: 2
  |     Condition C1 --> (LL:8)
  |     Condition C2 --> (LL:13)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2    Result
  |  1 { F,  -  = F      }
  |  2 { T,  T  = T      }
  |
  |  C1-Pair: covered: (1,2)
  |  C2-Pair: not covered
  |  MC/DC Coverage for Decision: 50.00%
  |
  ------------------
   LL|      1|        say("a and b");
   LL|      1|    } else {
   LL|      1|        say("not both");
   LL|      1|    }
   LL|      2|}
   LL|       |
   LL|      2|fn mcdc_check_b(a: bool, b: bool) {
   LL|      2|    if a && b {
  ------------------
  |  Branch (LL:8): [True: 2, False: 0]
  |  Branch (LL:13): [True: 1, False: 1]
  ------------------
  |---> MC/DC Decision Region (LL:8) to (LL:14)
  |
  |  Number of Conditions: 2
  |     Condition C1 --> (LL:8)
  |     Condition C2 --> (LL:13)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2    Result
  |  1 { T,  F  = F      }
  |  2 { T,  T  = T      }
  |
  |  C1-Pair: not covered
  |  C2-Pair: covered: (1,2)
  |  MC/DC Coverage for Decision: 50.00%
  |
  ------------------
   LL|      1|        say("a and b");
   LL|      1|    } else {
   LL|      1|        say("not both");
   LL|      1|    }
   LL|      2|}
   LL|       |
   LL|      3|fn mcdc_check_both(a: bool, b: bool) {
   LL|      3|    if a && b {
                          ^2
  ------------------
  |  Branch (LL:8): [True: 2, False: 1]
  |  Branch (LL:13): [True: 1, False: 1]
  ------------------
  |---> MC/DC Decision Region (LL:8) to (LL:14)
  |
  |  Number of Conditions: 2
  |     Condition C1 --> (LL:8)
  |     Condition C2 --> (LL:13)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2    Result
  |  1 { F,  -  = F      }
  |  2 { T,  F  = F      }
  |  3 { T,  T  = T      }
  |
  |  C1-Pair: covered: (1,3)
  |  C2-Pair: covered: (2,3)
  |  MC/DC Coverage for Decision: 100.00%
  |
  ------------------
   LL|      1|        say("a and b");
   LL|      2|    } else {
   LL|      2|        say("not both");
   LL|      2|    }
   LL|      3|}
   LL|       |
   LL|      4|fn mcdc_check_tree_decision(a: bool, b: bool, c: bool) {
   LL|       |    // This expression is intentionally written in a way
   LL|       |    // where 100% branch coverage indicates 100% mcdc coverage.
   LL|      4|    if a && (b || c) {
                           ^3   ^2
  ------------------
  |  Branch (LL:8): [True: 3, False: 1]
  |  Branch (LL:14): [True: 1, False: 2]
  |  Branch (LL:19): [True: 1, False: 1]
  ------------------
  |---> MC/DC Decision Region (LL:8) to (LL:21)
  |
  |  Number of Conditions: 3
  |     Condition C1 --> (LL:8)
  |     Condition C2 --> (LL:14)
  |     Condition C3 --> (LL:19)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2, C3    Result
  |  1 { F,  -,  -  = F      }
  |  2 { T,  F,  F  = F      }
  |  3 { T,  F,  T  = T      }
  |  4 { T,  T,  -  = T      }
  |
  |  C1-Pair: covered: (1,3)
  |  C2-Pair: covered: (2,4)
  |  C3-Pair: covered: (2,3)
  |  MC/DC Coverage for Decision: 100.00%
  |
  ------------------
   LL|      2|        say("pass");
   LL|      2|    } else {
   LL|      2|        say("reject");
   LL|      2|    }
   LL|      4|}
   LL|       |
   LL|      4|fn mcdc_check_not_tree_decision(a: bool, b: bool, c: bool) {
   LL|       |    // Contradict to `mcdc_check_tree_decision`,
   LL|       |    // 100% branch coverage of this expression does not indicate 100% mcdc coverage.
   LL|      4|    if (a || b) && c {
                           ^1
  ------------------
  |  Branch (LL:9): [True: 3, False: 1]
  |  Branch (LL:14): [True: 1, False: 0]
  |  Branch (LL:20): [True: 2, False: 2]
  ------------------
  |---> MC/DC Decision Region (LL:8) to (LL:21)
  |
  |  Number of Conditions: 3
  |     Condition C1 --> (LL:9)
  |     Condition C2 --> (LL:14)
  |     Condition C3 --> (LL:20)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2, C3    Result
  |  1 { T,  -,  F  = F      }
  |  2 { F,  T,  T  = T      }
  |  3 { T,  -,  T  = T      }
  |
  |  C1-Pair: not covered
  |  C2-Pair: not covered
  |  C3-Pair: covered: (1,3)
  |  MC/DC Coverage for Decision: 33.33%
  |
  ------------------
   LL|      2|        say("pass");
   LL|      2|    } else {
   LL|      2|        say("reject");
   LL|      2|    }
   LL|      4|}
   LL|       |
   LL|      3|fn mcdc_nested_if(a: bool, b: bool, c: bool) {
   LL|      3|    if a || b {
                          ^0
  ------------------
  |  Branch (LL:8): [True: 3, False: 0]
  |  Branch (LL:13): [True: 0, False: 0]
  ------------------
  |---> MC/DC Decision Region (LL:8) to (LL:14)
  |
  |  Number of Conditions: 2
  |     Condition C1 --> (LL:8)
  |     Condition C2 --> (LL:13)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2    Result
  |  1 { T,  -  = T      }
  |
  |  C1-Pair: not covered
  |  C2-Pair: not covered
  |  MC/DC Coverage for Decision: 0.00%
  |
  ------------------
   LL|      3|        say("a or b");
   LL|      3|        if b && c {
                              ^2
  ------------------
  |  Branch (LL:12): [True: 2, False: 1]
  |  Branch (LL:17): [True: 1, False: 1]
  ------------------
  |---> MC/DC Decision Region (LL:12) to (LL:18)
  |
  |  Number of Conditions: 2
  |     Condition C1 --> (LL:12)
  |     Condition C2 --> (LL:17)
  |
  |  Executed MC/DC Test Vectors:
  |
  |     C1, C2    Result
  |  1 { F,  -  = F      }
  |  2 { T,  F  = F      }
  |  3 { T,  T  = T      }
  |
  |  C1-Pair: covered: (1,3)
  |  C2-Pair: covered: (2,3)
  |  MC/DC Coverage for Decision: 100.00%
  |
  ------------------
   LL|      1|            say("b and c");
   LL|      2|        }
   LL|      0|    } else {
   LL|      0|        say("neither a nor b");
   LL|      0|    }
   LL|      3|}
   LL|       |
   LL|       |#[coverage(off)]
   LL|       |fn main() {
   LL|       |    mcdc_check_neither(false, false);
   LL|       |    mcdc_check_neither(false, true);
   LL|       |
   LL|       |    mcdc_check_a(true, true);
   LL|       |    mcdc_check_a(false, true);
   LL|       |
   LL|       |    mcdc_check_b(true, true);
   LL|       |    mcdc_check_b(true, false);
   LL|       |
   LL|       |    mcdc_check_both(false, true);
   LL|       |    mcdc_check_both(true, true);
   LL|       |    mcdc_check_both(true, false);
   LL|       |
   LL|       |    mcdc_check_tree_decision(false, true, true);
   LL|       |    mcdc_check_tree_decision(true, true, false);
   LL|       |    mcdc_check_tree_decision(true, false, false);
   LL|       |    mcdc_check_tree_decision(true, false, true);
   LL|       |
   LL|       |    mcdc_check_not_tree_decision(false, true, true);
   LL|       |    mcdc_check_not_tree_decision(true, true, false);
   LL|       |    mcdc_check_not_tree_decision(true, false, false);
   LL|       |    mcdc_check_not_tree_decision(true, false, true);
   LL|       |
   LL|       |    mcdc_nested_if(true, false, true);
   LL|       |    mcdc_nested_if(true, true, true);
   LL|       |    mcdc_nested_if(true, true, false);
   LL|       |}
   LL|       |
   LL|       |#[coverage(off)]
   LL|       |fn say(message: &str) {
   LL|       |    core::hint::black_box(message);
   LL|       |}