clang/test/Index/missing_vfs.c

// RUN: c-index-test -test-load-source local %s -ivfsoverlay %t/does-not-exist.yaml &> %t.out
// RUN: FileCheck -check-prefix=STDERR %s < %t.out
// STDERR: fatal error: virtual filesystem overlay file '{{.*}}' not found
// RUN: FileCheck %s < %t.out
// CHECK: missing_vfs.c:[[@LINE+1]]:6: FunctionDecl=foo:[[@LINE+1]]:6
void foo(void);