Auto merge of #124636 - tbu-:pr_env_unsafe, r=petrochenkov

Make `std::env::{set_var, remove_var}` unsafe in edition 2024

Allow calling these functions without `unsafe` blocks in editions up until 2021, but don't trigger the `unused_unsafe` lint for `unsafe` blocks containing these functions.

Fixes #27970.
Fixes #90308.
CC #124866.

6 files changed, 165 insertions, 0 deletions

diff --git a/tests/ui/rust-2024/unsafe-env-suggestion.fixed b/tests/ui/rust-2024/unsafe-env-suggestion.fixed
new file mode 100644
index 00000000000..d9c738edfac
--- /dev/null
+++ b/tests/ui/rust-2024/unsafe-env-suggestion.fixed
@@ -0,0 +1,20 @@
+//@ run-rustfix
+
+#![deny(deprecated_safe)]
+
+use std::env;
+
+#[deny(unused_unsafe)]
+fn main() {
+    unsafe { env::set_var("FOO", "BAR") };
+    //~^ ERROR call to deprecated safe function
+    //~| WARN this is accepted in the current edition
+    unsafe { env::remove_var("FOO") };
+    //~^ ERROR call to deprecated safe function
+    //~| WARN this is accepted in the current edition
+
+    unsafe {
+        env::set_var("FOO", "BAR");
+        env::remove_var("FOO");
+    }
+}
diff --git a/tests/ui/rust-2024/unsafe-env-suggestion.rs b/tests/ui/rust-2024/unsafe-env-suggestion.rs
new file mode 100644
index 00000000000..3bd169973e3
--- /dev/null
+++ b/tests/ui/rust-2024/unsafe-env-suggestion.rs
@@ -0,0 +1,20 @@
+//@ run-rustfix
+
+#![deny(deprecated_safe)]
+
+use std::env;
+
+#[deny(unused_unsafe)]
+fn main() {
+    env::set_var("FOO", "BAR");
+    //~^ ERROR call to deprecated safe function
+    //~| WARN this is accepted in the current edition
+    env::remove_var("FOO");
+    //~^ ERROR call to deprecated safe function
+    //~| WARN this is accepted in the current edition
+
+    unsafe {
+        env::set_var("FOO", "BAR");
+        env::remove_var("FOO");
+    }
+}
diff --git a/tests/ui/rust-2024/unsafe-env-suggestion.stderr b/tests/ui/rust-2024/unsafe-env-suggestion.stderr
new file mode 100644
index 00000000000..90c91c2a474
--- /dev/null
+++ b/tests/ui/rust-2024/unsafe-env-suggestion.stderr
@@ -0,0 +1,33 @@
+error: call to deprecated safe function `std::env::set_var` is unsafe and requires unsafe block
+  --> $DIR/unsafe-env-suggestion.rs:9:5
+   |
+LL |     env::set_var("FOO", "BAR");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
+   = note: for more information, see issue #27970 <https://github.com/rust-lang/rust/issues/27970>
+note: the lint level is defined here
+  --> $DIR/unsafe-env-suggestion.rs:3:9
+   |
+LL | #![deny(deprecated_safe)]
+   |         ^^^^^^^^^^^^^^^
+help: you can wrap the call in an `unsafe` block if you can guarantee the code is only ever called from single-threaded code
+   |
+LL |     unsafe { env::set_var("FOO", "BAR") };
+   |     ++++++++                            +
+
+error: call to deprecated safe function `std::env::remove_var` is unsafe and requires unsafe block
+  --> $DIR/unsafe-env-suggestion.rs:12:5
+   |
+LL |     env::remove_var("FOO");
+   |     ^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
+   = note: for more information, see issue #27970 <https://github.com/rust-lang/rust/issues/27970>
+help: you can wrap the call in an `unsafe` block if you can guarantee the code is only ever called from single-threaded code
+   |
+LL |     unsafe { env::remove_var("FOO") };
+   |     ++++++++                        +
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/rust-2024/unsafe-env.e2021.stderr b/tests/ui/rust-2024/unsafe-env.e2021.stderr
new file mode 100644
index 00000000000..cc40ec2e466
--- /dev/null
+++ b/tests/ui/rust-2024/unsafe-env.e2021.stderr
@@ -0,0 +1,23 @@
+error[E0133]: call to unsafe function `unsafe_fn` is unsafe and requires unsafe function or block
+  --> $DIR/unsafe-env.rs:23:5
+   |
+LL |     unsafe_fn();
+   |     ^^^^^^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: unnecessary `unsafe` block
+  --> $DIR/unsafe-env.rs:26:5
+   |
+LL |     unsafe {
+   |     ^^^^^^ unnecessary `unsafe` block
+   |
+note: the lint level is defined here
+  --> $DIR/unsafe-env.rs:11:8
+   |
+LL | #[deny(unused_unsafe)]
+   |        ^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0133`.
diff --git a/tests/ui/rust-2024/unsafe-env.e2024.stderr b/tests/ui/rust-2024/unsafe-env.e2024.stderr
new file mode 100644
index 00000000000..b43f817cf72
--- /dev/null
+++ b/tests/ui/rust-2024/unsafe-env.e2024.stderr
@@ -0,0 +1,39 @@
+error[E0133]: call to unsafe function `set_var` is unsafe and requires unsafe block
+  --> $DIR/unsafe-env.rs:13:5
+   |
+LL |     env::set_var("FOO", "BAR");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error[E0133]: call to unsafe function `remove_var` is unsafe and requires unsafe block
+  --> $DIR/unsafe-env.rs:15:5
+   |
+LL |     env::remove_var("FOO");
+   |     ^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error[E0133]: call to unsafe function `unsafe_fn` is unsafe and requires unsafe block
+  --> $DIR/unsafe-env.rs:23:5
+   |
+LL |     unsafe_fn();
+   |     ^^^^^^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: unnecessary `unsafe` block
+  --> $DIR/unsafe-env.rs:26:5
+   |
+LL |     unsafe {
+   |     ^^^^^^ unnecessary `unsafe` block
+   |
+note: the lint level is defined here
+  --> $DIR/unsafe-env.rs:11:8
+   |
+LL | #[deny(unused_unsafe)]
+   |        ^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0133`.
diff --git a/tests/ui/rust-2024/unsafe-env.rs b/tests/ui/rust-2024/unsafe-env.rs
new file mode 100644
index 00000000000..a882f077b9b
--- /dev/null
+++ b/tests/ui/rust-2024/unsafe-env.rs
@@ -0,0 +1,30 @@
+//@ revisions: e2021 e2024
+//@[e2021] edition: 2021
+//@[e2024] edition: 2024
+//@[e2024] compile-flags: -Zunstable-options
+
+use std::env;
+
+unsafe fn unsafe_fn() {}
+fn safe_fn() {}
+
+#[deny(unused_unsafe)]
+fn main() {
+    env::set_var("FOO", "BAR");
+    //[e2024]~^ ERROR call to unsafe function `set_var` is unsafe
+    env::remove_var("FOO");
+    //[e2024]~^ ERROR call to unsafe function `remove_var` is unsafe
+
+    unsafe {
+        env::set_var("FOO", "BAR");
+        env::remove_var("FOO");
+    }
+
+    unsafe_fn();
+    //~^ ERROR call to unsafe function `unsafe_fn` is unsafe
+
+    unsafe {
+        //~^ ERROR unnecessary `unsafe` block
+        safe_fn();
+    }
+}