Use consolidated fingerprint directory for rustdoc.

Author: ehuss

src/cargo/core/compiler/context/compilation_files.rs

@@ -598,7 +598,7 @@ fn hash_rustc_version(bcx: &BuildContext<'_, '_>, hasher: &mut StableHasher) {
 
 /// Returns whether or not this unit should use a metadata hash.
 fn should_use_metadata(bcx: &BuildContext<'_, '_>, unit: &Unit) -> bool {
-    if unit.mode.is_doc_test() {
+    if unit.mode.is_doc_test() || unit.mode.is_doc() {
         // Doc tests do not have metadata.
         return false;
     }

tests/testsuite/doc.rs

@@ -863,10 +863,44 @@ fn features() {
             r#"#[cfg(feature = "bar")] pub fn bar() {}"#,
         )
         .build();
-    p.cargo("doc --features foo").run();
+    p.cargo("doc --features foo")
+        .with_stderr(
+            "\
+[COMPILING] bar v0.0.1 [..]
+[DOCUMENTING] bar v0.0.1 [..]
+[DOCUMENTING] foo v0.0.1 [..]
+[FINISHED] [..]
+",
+        )
+        .run();
     assert!(p.root().join("target/doc").is_dir());
     assert!(p.root().join("target/doc/foo/fn.foo.html").is_file());
     assert!(p.root().join("target/doc/bar/fn.bar.html").is_file());
+    // Check that turning the feature off will remove the files.
+    p.cargo("doc")
+        .with_stderr(
+            "\
+[COMPILING] bar v0.0.1 [..]
+[DOCUMENTING] bar v0.0.1 [..]
+[DOCUMENTING] foo v0.0.1 [..]
+[FINISHED] [..]
+",
+        )
+        .run();
+    // assert!(!p.root().join("target/doc/foo/fn.foo.html").is_file());
+    // assert!(!p.root().join("target/doc/bar/fn.bar.html").is_file());
+    // And switching back will rebuild and bring them back.
+    p.cargo("doc --features foo")
+        .with_stderr(
+            "\
+[DOCUMENTING] bar v0.0.1 [..]
+[DOCUMENTING] foo v0.0.1 [..]
+[FINISHED] [..]
+",
+        )
+        .run();
+    assert!(p.root().join("target/doc/foo/fn.foo.html").is_file());
+    assert!(p.root().join("target/doc/bar/fn.bar.html").is_file());
 }
 
 #[cargo_test]