cgen: fix VUNREACHABLE inside ternary (#10672)

vlib/v/gen/c/fn.v

@@ -528,8 +528,16 @@ fn (mut g Gen) call_expr(node ast.CallExpr) {
 		}
 	}
 	if node.is_noreturn {
+		if g.inside_ternary == 0 {
 			g.writeln(';')
 			g.write('VUNREACHABLE()')
+		} else {
+			$if msvc {
+				// MSVC has no support for the statement expressions used below
+			} $else {
+				g.write(', ({VUNREACHABLE();})')
+			}
+		}
 	}
 }
 

vlib/v/tests/unreachable_code_paths_test.v

@@ -0,0 +1,11 @@
+fn test_inside_ternary() {
+	x := if false {
+		'foo'
+	} else if true {
+		'bar'
+	} else {
+		panic('err')
+		'empty'
+	}
+	assert x == 'bar'
+}