Add THIR building test.

tests/ui/thir-print/offset_of.rs

@@ -0,0 +1,49 @@
+//@ compile-flags: -Zunpretty=thir-tree --crate-type=lib
+//@ normalize-stdout: "DefId\([^ ]* ~ (\w*)\[....\]" -> "DefId($1"
+//@ check-pass
+
+#![feature(offset_of_enum)]
+
+use std::marker::PhantomData;
+use std::mem::offset_of;
+
+struct Alpha {
+    x: u8,
+    y: u16,
+    z: Beta,
+}
+
+struct Beta(u8, u8);
+
+struct Gamma<T> {
+    x: u8,
+    y: u16,
+    _t: T,
+}
+
+#[repr(C)]
+struct Delta<T> {
+    _phantom: PhantomData<T>,
+    x: u8,
+    y: u16,
+}
+
+enum Blah {
+    A,
+    B { x: u8, y: usize },
+}
+
+pub fn concrete() {
+    let x = offset_of!(Alpha, x);
+    let y = offset_of!(Alpha, y);
+    let h = offset_of!(Blah, B.y);
+    let z0 = offset_of!(Alpha, z.0);
+    let z1 = offset_of!(Alpha, z.1);
+}
+
+pub fn generic<T>() {
+    let gx = offset_of!(Gamma<T>, x);
+    let gy = offset_of!(Gamma<T>, y);
+    let dx = offset_of!(Delta<T>, x);
+    let dy = offset_of!(Delta<T>, y);
+}