Auto merge of #126733 - ZhuUx:llvm-19-adapt, r=Zalathar

[Coverage][MCDC] Adapt mcdc to llvm 19

Related issue: #126672

Also finish task 4 at #124144

[llvm #82448](https://github.com/llvm/llvm-project/pull/82448) has introduced some break changes into mcdc, causing incompatibility between llvm 18 and 19. This draft adapts to that change and gives up supporting for llvm-18.

1 files changed, 5 insertions, 19 deletions

diff --git a/tests/coverage/mcdc/condition-limit.rs b/tests/coverage/mcdc/condition-limit.rs
index 0d8546b01cd..2e8f1619379 100644
--- a/tests/coverage/mcdc/condition-limit.rs
+++ b/tests/coverage/mcdc/condition-limit.rs
@@ -1,25 +1,11 @@
 #![feature(coverage_attribute)]
 //@ edition: 2021
-//@ ignore-llvm-version: 19 - 99
+//@ min-llvm-version: 19
 //@ compile-flags: -Zcoverage-options=mcdc
 //@ llvm-cov-flags: --show-branches=count --show-mcdc
 
-// Check that MC/DC instrumentation can gracefully handle conditions that
-// exceed LLVM's limit of 6 conditions per decision.
-//
-// (The limit is enforced in `compiler/rustc_mir_build/src/build/coverageinfo/mcdc.rs`.)
-
-fn good() {
-    // With only 6 conditions, perform full MC/DC instrumentation.
-    let [a, b, c, d, e, f] = <[bool; 6]>::default();
-    if a && b && c && d && e && f {
-        core::hint::black_box("hello");
-    }
-}
-
-fn bad() {
-    // With 7 conditions, fall back to branch instrumentation only.
-    let [a, b, c, d, e, f, g] = <[bool; 7]>::default();
+fn accept_7_conditions(bool_arr: [bool; 7]) {
+    let [a, b, c, d, e, f, g] = bool_arr;
     if a && b && c && d && e && f && g {
         core::hint::black_box("hello");
     }
@@ -27,6 +13,6 @@ fn bad() {
 
 #[coverage(off)]
 fn main() {
-    good();
-    bad();
+    accept_7_conditions([false; 7]);
+    accept_7_conditions([true; 7]);
 }