[MC/DC] Update CoverageMapping tests (#125404)

To resolve the error, rename mcdc-error-nests.cpp ->
mcdc-nested-expr.cpp at first.

- `func_condop` A corner case that contains close decisions.
- `func_expect` Uses `__builtin_expect`. (#124565)
- `func_lnot` Contains logical not(s) `!` among MC/DC binary operators.
(#124563)

Author: chapuni

clang/test/CoverageMapping/mcdc-error-nests.cpp

@@ -0,0 +1,34 @@
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++11 -fcoverage-mcdc -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only %s 2> %t.stderr.txt | FileCheck %s
+// RUN: FileCheck %s --check-prefix=WARN < %t.stderr.txt
+
+// "Split-nest" -- boolean expressions within boolean expressions.
+extern bool bar(bool);
+// CHECK: func_split_nest{{.*}}:
+bool func_split_nest(bool a, bool b, bool c, bool d, bool e, bool f, bool g) {
+  // WARN: :[[@LINE+1]]:14: warning: unsupported MC/DC boolean expression; contains an operation with a nested boolean expression.
+  bool res = a && b && c && bar(d && e) && f && g;
+  return bar(res);
+}
+
+// The inner expr begins with the same Loc as the outer expr
+// CHECK: func_condop{{.*}}:
+bool func_condop(bool a, bool b, bool c) {
+  // WARN: :[[@LINE+1]]:10: warning: unsupported MC/DC boolean expression; contains an operation with a nested boolean expression.
+  return (a && b ? true : false) && c;
+}
+
+// __builtin_expect
+// Treated as parentheses.
+// CHECK: func_expect{{.*}}:
+bool func_expect(bool a, bool b, bool c) {
+  // WARN: :[[@LINE+1]]:10: warning: unsupported MC/DC boolean expression; contains an operation with a nested boolean expression.
+  return a || __builtin_expect(b && c, true);
+}
+
+// LNot among BinOp(s)
+// Doesn't split exprs.
+// CHECK: func_lnot{{.*}}:
+bool func_lnot(bool a, bool b, bool c, bool d) {
+  // WARN: :[[@LINE+1]]:10: warning: unsupported MC/DC boolean expression; contains an operation with a nested boolean expression.
+  return !(a || b) && !(c && d);
+}