Disable MC/DC tests on LLVM 19

Disable the tests and generate an error if MC/DC is used on LLVM 19.
The support will be ported separately, as it is substantially
different on LLVM 19, and there are no plans to support both
versions.

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1555,7 +1555,7 @@ LLVMRustGetInstrProfMCDCTVBitmapUpdateIntrinsic(LLVMModuleRef M) {
 
 extern "C" LLVMValueRef
 LLVMRustGetInstrProfMCDCCondBitmapIntrinsic(LLVMModuleRef M) {
-#if LLVM_VERSION_GE(18, 0)
+#if LLVM_VERSION_GE(18, 0) && LLVM_VERSION_LT(19, 0)
   return wrap(llvm::Intrinsic::getDeclaration(
       unwrap(M), llvm::Intrinsic::instrprof_mcdc_condbitmap_update));
 #else

tests/coverage/mcdc/condition-limit.rs

@@ -1,6 +1,7 @@
 #![feature(coverage_attribute)]
 //@ edition: 2021
 //@ min-llvm-version: 18
+//@ ignore-llvm-version: 19 - 99
 //@ compile-flags: -Zcoverage-options=mcdc
 //@ llvm-cov-flags: --show-branches=count --show-mcdc
 

tests/coverage/mcdc/if.rs

@@ -1,6 +1,7 @@
 #![feature(coverage_attribute)]
 //@ edition: 2021
 //@ min-llvm-version: 18
+//@ ignore-llvm-version: 19 - 99
 //@ compile-flags: -Zcoverage-options=mcdc
 //@ llvm-cov-flags: --show-branches=count --show-mcdc
 

tests/coverage/mcdc/inlined_expressions.rs

@@ -1,6 +1,7 @@
 #![feature(coverage_attribute)]
 //@ edition: 2021
 //@ min-llvm-version: 18
+//@ ignore-llvm-version: 19 - 99
 //@ compile-flags: -Zcoverage-options=mcdc -Copt-level=z -Cllvm-args=--inline-threshold=0
 //@ llvm-cov-flags: --show-branches=count --show-mcdc
 

tests/coverage/mcdc/nested_if.rs

@@ -1,6 +1,7 @@
 #![feature(coverage_attribute)]
 //@ edition: 2021
 //@ min-llvm-version: 18
+//@ ignore-llvm-version: 19 - 99
 //@ compile-flags: -Zcoverage-options=mcdc
 //@ llvm-cov-flags: --show-branches=count --show-mcdc
 

tests/coverage/mcdc/non_control_flow.rs

@@ -1,6 +1,7 @@
 #![feature(coverage_attribute)]
 //@ edition: 2021
 //@ min-llvm-version: 18
+//@ ignore-llvm-version: 19 - 99
 //@ compile-flags: -Zcoverage-options=mcdc
 //@ llvm-cov-flags: --show-branches=count --show-mcdc