Move /src/test to /tests

tests/incremental/cache_file_headers.rs

@@ -0,0 +1,20 @@
+// This test case makes sure that the compiler does not try to re-use anything
+// from the incremental compilation cache if the cache was produced by a
+// different compiler version. This is tested by artificially forcing the
+// emission of a different compiler version in the header of rpass1 artifacts,
+// and then making sure that the only object file of the test program gets
+// re-codegened although the program stays unchanged.
+
+// The `l33t haxx0r` Rust compiler is known to produce incr. comp. artifacts
+// that are outrageously incompatible with just about anything, even itself:
+//[rpass1] rustc-env:RUSTC_FORCE_RUSTC_VERSION="l33t haxx0r rustc 2.1 LTS"
+
+// revisions:rpass1 rpass2
+// compile-flags: -Z query-dep-graph
+
+#![feature(rustc_attrs)]
+#![rustc_partition_codegened(module="cache_file_headers", cfg="rpass2")]
+
+fn main() {
+    // empty
+}