add a rustc::query_stability lint

4 files changed, 95 insertions, 0 deletions

diff --git a/src/test/ui-fulldeps/internal-lints/query_stability.rs b/src/test/ui-fulldeps/internal-lints/query_stability.rs
new file mode 100644
index 00000000000..560675b4486
--- /dev/null
+++ b/src/test/ui-fulldeps/internal-lints/query_stability.rs
@@ -0,0 +1,24 @@
+// compile-flags: -Z unstable-options
+
+#![feature(rustc_private)]
+#![deny(rustc::potential_query_instability)]
+
+extern crate rustc_data_structures;
+
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+
+fn main() {
+    let mut x = FxHashMap::<u32, i32>::default();
+
+    for _ in x.drain() {}
+    //~^ ERROR using `drain` can result in unstable
+
+    for _ in x.iter() {}
+    //~^ ERROR using `iter`
+
+    for _ in Some(&mut x).unwrap().iter_mut() {}
+    //~^ ERROR using `iter_mut`
+
+    for _ in x {}
+    //~^ ERROR using `into_iter`
+}
diff --git a/src/test/ui-fulldeps/internal-lints/query_stability.stderr b/src/test/ui-fulldeps/internal-lints/query_stability.stderr
new file mode 100644
index 00000000000..7e8b448f41a
--- /dev/null
+++ b/src/test/ui-fulldeps/internal-lints/query_stability.stderr
@@ -0,0 +1,39 @@
+error: using `drain` can result in unstable query results
+  --> $DIR/query_stability.rs:13:16
+   |
+LL |     for _ in x.drain() {}
+   |                ^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/query_stability.rs:4:9
+   |
+LL | #![deny(rustc::potential_query_instability)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+
+error: using `iter` can result in unstable query results
+  --> $DIR/query_stability.rs:16:16
+   |
+LL |     for _ in x.iter() {}
+   |                ^^^^
+   |
+   = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+
+error: using `iter_mut` can result in unstable query results
+  --> $DIR/query_stability.rs:19:36
+   |
+LL |     for _ in Some(&mut x).unwrap().iter_mut() {}
+   |                                    ^^^^^^^^
+   |
+   = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+
+error: using `into_iter` can result in unstable query results
+  --> $DIR/query_stability.rs:22:14
+   |
+LL |     for _ in x {}
+   |              ^
+   |
+   = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+
+error: aborting due to 4 previous errors
+
diff --git a/src/test/ui-fulldeps/internal-lints/query_stability_incorrect.rs b/src/test/ui-fulldeps/internal-lints/query_stability_incorrect.rs
new file mode 100644
index 00000000000..f478b73329e
--- /dev/null
+++ b/src/test/ui-fulldeps/internal-lints/query_stability_incorrect.rs
@@ -0,0 +1,15 @@
+// compile-flags: -Z unstable-options
+
+#![feature(rustc_attrs)]
+
+#[rustc_lint_query_instability]
+//~^ ERROR attribute should be applied to a function
+struct Foo;
+
+impl Foo {
+    #[rustc_lint_query_instability(a)]
+    //~^ ERROR malformed `rustc_lint_query_instability`
+    fn bar() {}
+}
+
+fn main() {}
diff --git a/src/test/ui-fulldeps/internal-lints/query_stability_incorrect.stderr b/src/test/ui-fulldeps/internal-lints/query_stability_incorrect.stderr
new file mode 100644
index 00000000000..b5156f2ac59
--- /dev/null
+++ b/src/test/ui-fulldeps/internal-lints/query_stability_incorrect.stderr
@@ -0,0 +1,17 @@
+error: malformed `rustc_lint_query_instability` attribute input
+  --> $DIR/query_stability_incorrect.rs:10:5
+   |
+LL |     #[rustc_lint_query_instability(a)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_lint_query_instability]`
+
+error: attribute should be applied to a function
+  --> $DIR/query_stability_incorrect.rs:5:1
+   |
+LL | #[rustc_lint_query_instability]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |
+LL | struct Foo;
+   | ----------- not a function
+
+error: aborting due to 2 previous errors
+