Auto merge of #159343 - jackh726:enable-polonius-alpha, r=lqd,Kobzol

Enable polonius alpha on nightly



 See [rust-lang/compiler-team#](rust-lang/compiler-team#1015)

The first commit here adds an `-Zpolonius=nll` argument for tests and so people can disable alpha on nightly.

Author: bors

compiler/rustc_session/src/config.rs

@@ -3599,10 +3599,9 @@ impl PatchableFunctionEntry {
 
 /// `-Zpolonius` values, enabling the borrow checker polonius analysis, and which version: legacy,
 /// or future prototype.
-#[derive(Clone, Copy, PartialEq, Hash, Debug, Default)]
+#[derive(Clone, Copy, PartialEq, Hash, Debug)]
 pub enum Polonius {
-    /// The default value: disabled.
-    #[default]
+    /// Polonius is disabled, only use NLL.
     Off,
 
     /// Legacy version, using datalog and the `polonius-engine` crate. Historical value for `-Zpolonius`.
@@ -3612,6 +3611,12 @@ pub enum Polonius {
     Next,
 }
 
+impl Default for Polonius {
+    fn default() -> Self {
+        if option_env!("CFG_DEFAULT_POLONIUS_NEXT").is_some() { Self::Next } else { Self::Off }
+    }
+}
+
 impl Polonius {
     /// Returns whether the legacy version of polonius is enabled
     pub fn is_legacy_enabled(&self) -> bool {

compiler/rustc_session/src/options.rs

@@ -891,7 +891,8 @@ mod desc {
         components: `crto`, `libc`, `unwind`, `linker`, `sanitizers`, `mingw`";
     pub(crate) const parse_linker_features: &str =
         "a list of enabled (`+` prefix) and disabled (`-` prefix) features: `lld`";
-    pub(crate) const parse_polonius: &str = "either no value or `legacy` (the default), or `next`";
+    pub(crate) const parse_polonius: &str =
+        "either no value or one of `legacy` (the default), `off`, or `next`";
     pub(crate) const parse_annotate_moves: &str =
         "either a boolean (`yes`, `no`, `on`, `off`, etc.), or a size limit in bytes";
     pub(crate) const parse_stack_protector: &str =
@@ -985,6 +986,10 @@ pub mod parse {
                 *slot = Polonius::Next;
                 true
             }
+            Some("off") | Some("no") => {
+                *slot = Polonius::Off;
+                true
+            }
             _ => false,
         }
     }

src/bootstrap/src/core/build_steps/compile.rs

@@ -1369,6 +1369,12 @@ pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetS
         cargo.env("RUSTC_VERIFY_LLVM_IR", "1");
     }
 
+    let nightly = builder.config.channel == "nightly" || builder.config.channel == "dev";
+    if nightly {
+        // We want to enable Polonius Alpha by default on nighty
+        cargo.env("CFG_DEFAULT_POLONIUS_NEXT", "1");
+    }
+
     // These conditionals represent a tension between three forces:
     // - For non-check builds, we need to define some LLVM-related environment
     //   variables, requiring LLVM to have been built.

tests/ui/borrowck/alias-liveness/gat-hide-lifetime-for-swap.edition2015.stderr

@@ -1,5 +1,5 @@
 error[E0515]: cannot return value referencing local variable `x`
-  --> $DIR/gat-hide-lifetime-for-swap.rs:33:5
+  --> $DIR/gat-hide-lifetime-for-swap.rs:35:5
    |
 LL |     h.hide_ref(&mut res).swap(h.hide_ref(&mut &x));
    |                                               -- `x` is borrowed here

tests/ui/borrowck/alias-liveness/gat-hide-lifetime-for-swap.edition2024.stderr

@@ -1,5 +1,5 @@
 error[E0515]: cannot return value referencing local variable `x`
-  --> $DIR/gat-hide-lifetime-for-swap.rs:33:5
+  --> $DIR/gat-hide-lifetime-for-swap.rs:35:5
    |
 LL |     h.hide_ref(&mut res).swap(h.hide_ref(&mut &x));
    |                                               -- `x` is borrowed here

tests/ui/borrowck/alias-liveness/gat-hide-lifetime-for-swap.polonius_alpha.stderr

@@ -1,5 +1,5 @@
 error[E0515]: cannot return value referencing local variable `x`
-  --> $DIR/gat-hide-lifetime-for-swap.rs:33:5
+  --> $DIR/gat-hide-lifetime-for-swap.rs:35:5
    |
 LL |     h.hide_ref(&mut res).swap(h.hide_ref(&mut &x));
    |                                               -- `x` is borrowed here

tests/ui/borrowck/alias-liveness/gat-hide-lifetime-for-swap.rs

@@ -2,6 +2,8 @@
 //@ ignore-compare-mode-polonius (explicit revisions)
 //@ [edition2015] edition: 2015
 //@ [edition2024] edition: 2024
+//@ [edition2015] compile-flags: -Zpolonius=off
+//@ [edition2024] compile-flags: -Zpolonius=off
 //@ [polonius_alpha] edition: 2024
 //@ [polonius_alpha] compile-flags: -Zpolonius=next
 

tests/ui/borrowck/alias-liveness/gat-hide-lifetime-in-type-arg-for-swap.edition2015.stderr

@@ -1,5 +1,5 @@
 error[E0515]: cannot return value referencing local variable `x`
-  --> $DIR/gat-hide-lifetime-in-type-arg-for-swap.rs:33:5
+  --> $DIR/gat-hide-lifetime-in-type-arg-for-swap.rs:35:5
    |
 LL |     h.hide(&mut res).swap(h.hide(&mut &x));
    |                                       -- `x` is borrowed here

tests/ui/borrowck/alias-liveness/gat-hide-lifetime-in-type-arg-for-swap.edition2024.stderr

@@ -1,5 +1,5 @@
 error[E0515]: cannot return value referencing local variable `x`
-  --> $DIR/gat-hide-lifetime-in-type-arg-for-swap.rs:33:5
+  --> $DIR/gat-hide-lifetime-in-type-arg-for-swap.rs:35:5
    |
 LL |     h.hide(&mut res).swap(h.hide(&mut &x));
    |                                       -- `x` is borrowed here

tests/ui/borrowck/alias-liveness/gat-hide-lifetime-in-type-arg-for-swap.polonius_alpha.stderr

@@ -1,5 +1,5 @@
 error[E0515]: cannot return value referencing local variable `x`
-  --> $DIR/gat-hide-lifetime-in-type-arg-for-swap.rs:33:5
+  --> $DIR/gat-hide-lifetime-in-type-arg-for-swap.rs:35:5
    |
 LL |     h.hide(&mut res).swap(h.hide(&mut &x));
    |                                       -- `x` is borrowed here