Auto merge of #55229 - nikomatsakis:issue-54692-closure-signatures, r=MatthewJasper

enforce user annotations in closure signatures

Not *quite* ready yet but I'm opening anyway. Still have to finish running tests locally.

Fixes #54692
Fixes #54124

r? @matthewjasper

16 files changed, 161 insertions, 65 deletions

diff --git a/src/test/incremental/hashes/closure_expressions.rs b/src/test/incremental/hashes/closure_expressions.rs
index 839e0ca8e01..8469f0aa664 100644
--- a/src/test/incremental/hashes/closure_expressions.rs
+++ b/src/test/incremental/hashes/closure_expressions.rs
@@ -95,7 +95,7 @@ pub fn add_type_ascription_to_parameter() {
 }
 
 #[cfg(not(cfail1))]
-#[rustc_clean(cfg="cfail2", except="HirBody")]
+#[rustc_clean(cfg="cfail2", except="HirBody, TypeckTables")]
 #[rustc_clean(cfg="cfail3")]
 pub fn add_type_ascription_to_parameter() {
     let closure = |x: u32| x + 1u32;
diff --git a/src/test/ui/issues/issue-28848.rs b/src/test/ui/issues/issue-28848.rs
index c13fd5fa716..1a06d59f0b1 100644
--- a/src/test/ui/issues/issue-28848.rs
+++ b/src/test/ui/issues/issue-28848.rs
@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// ignore-compare-mode-nll
-
 struct Foo<'a, 'b: 'a>(&'a &'b ());
 
 impl<'a, 'b> Foo<'a, 'b> {
diff --git a/src/test/ui/issues/issue-28848.stderr b/src/test/ui/issues/issue-28848.stderr
index dadcff226f5..738a1c0c6f6 100644
--- a/src/test/ui/issues/issue-28848.stderr
+++ b/src/test/ui/issues/issue-28848.stderr
@@ -1,16 +1,16 @@
 error[E0478]: lifetime bound not satisfied
-  --> $DIR/issue-28848.rs:22:5
+  --> $DIR/issue-28848.rs:20:5
    |
 LL |     Foo::<'a, 'b>::xmute(u) //~ ERROR lifetime bound not satisfied
    |     ^^^^^^^^^^^^^^^^^^^^
    |
-note: lifetime parameter instantiated with the lifetime 'b as defined on the function body at 21:16
-  --> $DIR/issue-28848.rs:21:16
+note: lifetime parameter instantiated with the lifetime 'b as defined on the function body at 19:16
+  --> $DIR/issue-28848.rs:19:16
    |
 LL | pub fn foo<'a, 'b>(u: &'b ()) -> &'a () {
    |                ^^
-note: but lifetime parameter must outlive the lifetime 'a as defined on the function body at 21:12
-  --> $DIR/issue-28848.rs:21:12
+note: but lifetime parameter must outlive the lifetime 'a as defined on the function body at 19:12
+  --> $DIR/issue-28848.rs:19:12
    |
 LL | pub fn foo<'a, 'b>(u: &'b ()) -> &'a () {
    |            ^^
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.rs b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.rs
index 49b62581640..4bef6cf8cd1 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.rs
+++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.rs
@@ -47,7 +47,6 @@ fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
 
         // Only works if 'x: 'y:
         demand_y(x, y, x.get())
-        //~^ ERROR unsatisfied lifetime constraints
     });
 }
 
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
index a5435cc65ca..f22dbdba934 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
@@ -7,7 +7,6 @@ LL | |         //~^ ERROR borrowed data escapes outside of function
 LL | |
 LL | |         // Only works if 'x: 'y:
 LL | |         demand_y(x, y, x.get())
-LL | |         //~^ ERROR unsatisfied lifetime constraints
 LL | |     });
    | |_____^
    |
@@ -44,21 +43,9 @@ LL | |         //~^ ERROR borrowed data escapes outside of function
 LL | |
 LL | |         // Only works if 'x: 'y:
 LL | |         demand_y(x, y, x.get())
-LL | |         //~^ ERROR unsatisfied lifetime constraints
 LL | |     });
    | |______^ `cell_a` escapes the function body here
 
-error: unsatisfied lifetime constraints
-  --> $DIR/propagate-approximated-shorter-to-static-no-bound.rs:49:9
-   |
-LL | fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
-   |           --  -- lifetime `'b` defined here
-   |           |
-   |           lifetime `'a` defined here
-...
-LL |         demand_y(x, y, x.get())
-   |         ^^^^^^^^^^^^^^^^^^^^^^^ argument requires that `'a` must outlive `'b`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0521`.
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.rs b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.rs
index 0181792cbdc..05e9818b91e 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.rs
+++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.rs
@@ -47,9 +47,9 @@ fn demand_y<'x, 'y>(_cell_x: &Cell<&'x u32>, _cell_y: &Cell<&'y u32>, _y: &'y u3
 fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
         //~^ ERROR borrowed data escapes outside of function
+
         // Only works if 'x: 'y:
         demand_y(x, y, x.get())
-        //~^ ERROR unsatisfied lifetime constraints
     });
 }
 
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
index 35692414081..2b1cb5a30ce 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
@@ -4,9 +4,9 @@ note: External requirements
 LL |       establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
    |  _______________________________________________^
 LL | |         //~^ ERROR borrowed data escapes outside of function
+LL | |
 LL | |         // Only works if 'x: 'y:
 LL | |         demand_y(x, y, x.get())
-LL | |         //~^ ERROR unsatisfied lifetime constraints
 LL | |     });
    | |_____^
    |
@@ -25,7 +25,7 @@ note: No external requirements
 LL | / fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
 LL | |     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
 LL | |         //~^ ERROR borrowed data escapes outside of function
-LL | |         // Only works if 'x: 'y:
+LL | |
 ...  |
 LL | |     });
 LL | | }
@@ -40,23 +40,12 @@ LL |   fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
    |                     ------ `cell_a` is a reference that is only valid in the function body
 LL | /     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
 LL | |         //~^ ERROR borrowed data escapes outside of function
+LL | |
 LL | |         // Only works if 'x: 'y:
 LL | |         demand_y(x, y, x.get())
-LL | |         //~^ ERROR unsatisfied lifetime constraints
 LL | |     });
    | |______^ `cell_a` escapes the function body here
 
-error: unsatisfied lifetime constraints
-  --> $DIR/propagate-approximated-shorter-to-static-wrong-bound.rs:51:9
-   |
-LL | fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
-   |           --  -- lifetime `'b` defined here
-   |           |
-   |           lifetime `'a` defined here
-...
-LL |         demand_y(x, y, x.get())
-   |         ^^^^^^^^^^^^^^^^^^^^^^^ argument requires that `'a` must outlive `'b`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0521`.
diff --git a/src/test/ui/nll/user-annotations/closure-substs.rs b/src/test/ui/nll/user-annotations/closure-substs.rs
new file mode 100644
index 00000000000..77c7315fa66
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/closure-substs.rs
@@ -0,0 +1,43 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(nll)]
+
+// Test that we enforce user-provided type annotations on closures.
+
+fn foo<'a>() {
+    // Here `x` is free in the closure sig:
+    |x: &'a i32| -> &'static i32 {
+        return x; //~ ERROR unsatisfied lifetime constraints
+    };
+}
+
+fn foo1() {
+    // Here `x` is bound in the closure sig:
+    |x: &i32| -> &'static i32 {
+        return x; //~ ERROR unsatisfied lifetime constraints
+    };
+}
+
+fn bar<'a>() {
+    // Here `x` is free in the closure sig:
+    |x: &'a i32, b: fn(&'static i32)| {
+        b(x); //~ ERROR unsatisfied lifetime constraints
+    };
+}
+
+fn bar1() {
+    // Here `x` is bound in the closure sig:
+    |x: &i32, b: fn(&'static i32)| {
+        b(x); //~ ERROR borrowed data escapes outside of closure
+    };
+}
+
+fn main() { }
diff --git a/src/test/ui/nll/user-annotations/closure-substs.stderr b/src/test/ui/nll/user-annotations/closure-substs.stderr
new file mode 100644
index 00000000000..c69d514d9e6
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/closure-substs.stderr
@@ -0,0 +1,37 @@
+error: unsatisfied lifetime constraints
+  --> $DIR/closure-substs.rs:18:16
+   |
+LL | fn foo<'a>() {
+   |        -- lifetime `'a` defined here
+...
+LL |         return x; //~ ERROR unsatisfied lifetime constraints
+   |                ^ returning this value requires that `'a` must outlive `'static`
+
+error: unsatisfied lifetime constraints
+  --> $DIR/closure-substs.rs:25:16
+   |
+LL |     |x: &i32| -> &'static i32 {
+   |         - let's call the lifetime of this reference `'1`
+LL |         return x; //~ ERROR unsatisfied lifetime constraints
+   |                ^ returning this value requires that `'1` must outlive `'static`
+
+error: unsatisfied lifetime constraints
+  --> $DIR/closure-substs.rs:32:9
+   |
+LL | fn bar<'a>() {
+   |        -- lifetime `'a` defined here
+...
+LL |         b(x); //~ ERROR unsatisfied lifetime constraints
+   |         ^^^^ argument requires that `'a` must outlive `'static`
+
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/closure-substs.rs:39:9
+   |
+LL |     |x: &i32, b: fn(&'static i32)| {
+   |      - `x` is a reference that is only valid in the closure body
+LL |         b(x); //~ ERROR borrowed data escapes outside of closure
+   |         ^^^^ `x` escapes the closure body here
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0521`.
diff --git a/src/test/ui/nll/user-annotations/issue-54124.rs b/src/test/ui/nll/user-annotations/issue-54124.rs
new file mode 100644
index 00000000000..8cdd390540a
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/issue-54124.rs
@@ -0,0 +1,9 @@
+#![feature(nll)]
+
+fn test<'a>() {
+    let _:fn(&()) = |_:&'a ()| {};
+}
+
+fn main() {
+    test();
+}
diff --git a/src/test/ui/nll/user-annotations/issue-54124.stderr b/src/test/ui/nll/user-annotations/issue-54124.stderr
new file mode 100644
index 00000000000..df5e4b0447c
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/issue-54124.stderr
@@ -0,0 +1,20 @@
+error: unsatisfied lifetime constraints
+  --> $DIR/issue-54124.rs:4:22
+   |
+LL | fn test<'a>() {
+   |         -- lifetime `'a` defined here
+LL |     let _:fn(&()) = |_:&'a ()| {};
+   |                      ^ - let's call the lifetime of this reference `'1`
+   |                      |
+   |                      requires that `'1` must outlive `'a`
+
+error: unsatisfied lifetime constraints
+  --> $DIR/issue-54124.rs:4:22
+   |
+LL | fn test<'a>() {
+   |         -- lifetime `'a` defined here
+LL |     let _:fn(&()) = |_:&'a ()| {};
+   |                      ^ requires that `'a` must outlive `'static`
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/nll/user-annotations/wf-self-type.rs b/src/test/ui/nll/user-annotations/wf-self-type.rs
new file mode 100644
index 00000000000..c3cb3068bce
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/wf-self-type.rs
@@ -0,0 +1,25 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(nll)]
+
+struct Foo<'a, 'b: 'a>(&'a &'b ());
+
+impl<'a, 'b> Foo<'a, 'b> {
+    fn xmute(a: &'b ()) -> &'a () {
+        unreachable!()
+    }
+}
+
+pub fn foo<'a, 'b>(u: &'b ()) -> &'a () {
+    Foo::xmute(u) //~ ERROR unsatisfied lifetime constraints
+}
+
+fn main() {}
diff --git a/src/test/ui/nll/user-annotations/wf-self-type.stderr b/src/test/ui/nll/user-annotations/wf-self-type.stderr
new file mode 100644
index 00000000000..78d86fbf17e
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/wf-self-type.stderr
@@ -0,0 +1,12 @@
+error: unsatisfied lifetime constraints
+  --> $DIR/wf-self-type.rs:22:5
+   |
+LL | pub fn foo<'a, 'b>(u: &'b ()) -> &'a () {
+   |            --  -- lifetime `'b` defined here
+   |            |
+   |            lifetime `'a` defined here
+LL |     Foo::xmute(u) //~ ERROR unsatisfied lifetime constraints
+   |     ^^^^^^^^^^^^^ returning this value requires that `'b` must outlive `'a`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/regions/regions-static-bound.ll.stderr b/src/test/ui/regions/regions-static-bound.ll.stderr
index 16add00eb41..cf291279210 100644
--- a/src/test/ui/regions/regions-static-bound.ll.stderr
+++ b/src/test/ui/regions/regions-static-bound.ll.stderr
@@ -20,7 +20,7 @@ LL |     static_id(&u); //[ll]~ ERROR explicit lifetime required in the type of
    |     ^^^^^^^^^ lifetime `'static` required
 
 error[E0621]: explicit lifetime required in the type of `v`
-  --> $DIR/regions-static-bound.rs:27:5
+  --> $DIR/regions-static-bound.rs:26:5
    |
 LL | fn error(u: &(), v: &()) {
    |                     --- help: add explicit lifetime `'static` to the type of `v`: `&'static ()`
diff --git a/src/test/ui/regions/regions-static-bound.nll.stderr b/src/test/ui/regions/regions-static-bound.nll.stderr
index dc3a32cec6a..462fbe8ee19 100644
--- a/src/test/ui/regions/regions-static-bound.nll.stderr
+++ b/src/test/ui/regions/regions-static-bound.nll.stderr
@@ -15,7 +15,7 @@ LL |     static_id(&u); //[ll]~ ERROR explicit lifetime required in the type of
    |     ^^^^^^^^^^^^^ lifetime `'static` required
 
 error[E0621]: explicit lifetime required in the type of `v`
-  --> $DIR/regions-static-bound.rs:27:5
+  --> $DIR/regions-static-bound.rs:26:5
    |
 LL | fn error(u: &(), v: &()) {
    |                     --- help: add explicit lifetime `'static` to the type of `v`: `&'static ()`
@@ -23,27 +23,6 @@ LL | fn error(u: &(), v: &()) {
 LL |     static_id_indirect(&v); //[ll]~ ERROR explicit lifetime required in the type of `v` [E0621]
    |     ^^^^^^^^^^^^^^^^^^^^^^ lifetime `'static` required
 
-error: unsatisfied lifetime constraints
-  --> $DIR/regions-static-bound.rs:24:5
-   |
-LL | fn error(u: &(), v: &()) {
-   |             -       - let's call the lifetime of this reference `'2`
-   |             |
-   |             let's call the lifetime of this reference `'1`
-LL |     static_id(&u); //[ll]~ ERROR explicit lifetime required in the type of `u` [E0621]
-   |     ^^^^^^^^^^^^^ argument requires that `'1` must outlive `'2`
-
-error: unsatisfied lifetime constraints
-  --> $DIR/regions-static-bound.rs:27:5
-   |
-LL | fn error(u: &(), v: &()) {
-   |             -       - let's call the lifetime of this reference `'1`
-   |             |
-   |             let's call the lifetime of this reference `'2`
-...
-LL |     static_id_indirect(&v); //[ll]~ ERROR explicit lifetime required in the type of `v` [E0621]
-   |     ^^^^^^^^^^^^^^^^^^^^^^ argument requires that `'1` must outlive `'2`
-
-error: aborting due to 5 previous errors
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0621`.
diff --git a/src/test/ui/regions/regions-static-bound.rs b/src/test/ui/regions/regions-static-bound.rs
index 34baf5ffff0..c5dc6000e83 100644
--- a/src/test/ui/regions/regions-static-bound.rs
+++ b/src/test/ui/regions/regions-static-bound.rs
@@ -23,10 +23,8 @@ fn static_id_wrong_way<'a>(t: &'a ()) -> &'static () where 'static: 'a {
 fn error(u: &(), v: &()) {
     static_id(&u); //[ll]~ ERROR explicit lifetime required in the type of `u` [E0621]
     //[nll]~^ ERROR explicit lifetime required in the type of `u` [E0621]
-    //[nll]~| ERROR unsatisfied lifetime constraints
     static_id_indirect(&v); //[ll]~ ERROR explicit lifetime required in the type of `v` [E0621]
     //[nll]~^ ERROR explicit lifetime required in the type of `v` [E0621]
-    //[nll]~| ERROR unsatisfied lifetime constraints
 }
 
 fn main() {}