Add tests for unwind no_std.

src/test/ui/panic-runtime/unwind-msvc-no-std-link-to-libcmt.rs

@@ -0,0 +1,47 @@
+// build-pass
+// compile-flags: -C panic=unwind -C target-feature=+crt-static
+// only-msvc
+// Test that `no_std` with `panic=unwind` under MSVC toolchain
+// doesn't cause error when linking to libcmt.
+
+#![no_std]
+#![no_main]
+#![feature(alloc_error_handler)]
+#![feature(panic_unwind)]
+
+use core::alloc::{GlobalAlloc, Layout};
+
+struct DummyAllocator;
+
+unsafe impl GlobalAlloc for DummyAllocator {
+    unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
+        core::ptr::null_mut()
+    }
+
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {}
+}
+
+#[global_allocator]
+static ALLOC: DummyAllocator = DummyAllocator;
+
+#[alloc_error_handler]
+fn rust_oom(_layout: Layout) -> ! {
+    panic!()
+}
+
+extern crate panic_unwind;
+
+use core::panic::PanicInfo;
+
+#[panic_handler]
+fn handle_panic(_: &PanicInfo) -> ! {
+    loop {}
+}
+
+#[link(name = "libcmt")]
+extern "C" {}
+
+#[no_mangle]
+pub extern "C" fn main() -> i32 {
+    panic!();
+}

src/test/ui/panic-runtime/unwind-msvc-no-std-link-to-msvcrt.rs

@@ -0,0 +1,47 @@
+// build-pass
+// compile-flags: -C panic=unwind
+// only-msvc
+// Test that `no_std` with `panic=unwind` under MSVC toolchain
+// doesn't cause error when linking to msvcrt.
+
+#![no_std]
+#![no_main]
+#![feature(alloc_error_handler)]
+#![feature(panic_unwind)]
+
+use core::alloc::{GlobalAlloc, Layout};
+
+struct DummyAllocator;
+
+unsafe impl GlobalAlloc for DummyAllocator {
+    unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
+        core::ptr::null_mut()
+    }
+
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {}
+}
+
+#[global_allocator]
+static ALLOC: DummyAllocator = DummyAllocator;
+
+#[alloc_error_handler]
+fn rust_oom(_layout: Layout) -> ! {
+    panic!()
+}
+
+extern crate panic_unwind;
+
+use core::panic::PanicInfo;
+
+#[panic_handler]
+fn handle_panic(_: &PanicInfo) -> ! {
+    loop {}
+}
+
+#[link(name = "msvcrt")]
+extern "C" {}
+
+#[no_mangle]
+pub extern "C" fn main() -> i32 {
+    panic!();
+}