Unrolled build for rust-lang#121560

Rollup merge of rust-lang#121560 - Noratrieb:stop-lint-macro-nonsense, r=jieyouxu

Allow `#[deny]` inside `#[forbid]` as a no-op

Forbid cannot be overriden. When someome tries to do this anyways, it results in a hard error. That makes sense.

Except it doesn't, because macros. Macros may reasonably use `#[deny]` (or `#[warn]` for an allow-by-default lint) in their expansion to assert that their expanded code follows the lint. This is doesn't work when the output gets expanded into a `forbid()` context. This is pretty silly, since both the macros and the code agree on the lint!

By making it a warning instead, we remove the problem with the macro, which is now nothing as warnings are suppressed in macro expanded code, while still telling users that something is up.

fixes rust-lang#121483

Author: rust-timer

compiler/rustc_lint/src/levels.rs

@@ -493,7 +493,10 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
         //
         // This means that this only errors if we're truly lowering the lint
         // level from forbid.
-        if self.lint_added_lints && level != Level::Forbid && old_level == Level::Forbid {
+        if self.lint_added_lints && level == Level::Deny && old_level == Level::Forbid {
+            // Having a deny inside a forbid is fine and is ignored, so we skip this check.
+            return;
+        } else if self.lint_added_lints && level != Level::Forbid && old_level == Level::Forbid {
             // Backwards compatibility check:
             //
             // We used to not consider `forbid(lint_group)`

compiler/rustc_lint_defs/src/builtin.rs

@@ -156,7 +156,7 @@ declare_lint! {
     ///
     /// ```rust
     /// #![forbid(warnings)]
-    /// #![deny(bad_style)]
+    /// #![warn(bad_style)]
     ///
     /// fn main() {}
     /// ```

src/tools/tidy/src/issues.txt

@@ -2758,7 +2758,6 @@ ui/lint/issue-63364.rs
 ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs
 ui/lint/issue-79546-fuel-ice.rs
 ui/lint/issue-79744.rs
-ui/lint/issue-80988.rs
 ui/lint/issue-81218.rs
 ui/lint/issue-83477.rs
 ui/lint/issue-87274-paren-parent.rs

tests/ui/lint/auxiliary/allow-macro.rs

@@ -0,0 +1,7 @@
+#[macro_export]
+macro_rules! emit_allow {
+    () => {
+        #[allow(unsafe_code)]
+        let _so_safe = 0;
+    };
+}

tests/ui/lint/auxiliary/deny-macro.rs

@@ -0,0 +1,7 @@
+#[macro_export]
+macro_rules! emit_deny {
+    () => {
+        #[deny(unsafe_code)]
+        let _so_safe = 0;
+    };
+}

tests/ui/lint/auxiliary/forbid-macro.rs

@@ -0,0 +1,7 @@
+#[macro_export]
+macro_rules! emit_forbid {
+    () => {
+        #[forbid(unsafe_code)]
+        let _so_safe = 0;
+    };
+}

tests/ui/lint/auxiliary/warn-macro.rs

@@ -0,0 +1,7 @@
+#[macro_export]
+macro_rules! emit_warn {
+    () => {
+        #[warn(unsafe_code)]
+        let _so_safe = 0;
+    };
+}

tests/ui/lint/deny-inside-forbid-ignored.cli_forbid.stderr

@@ -0,0 +1,35 @@
+error[E0453]: allow(unsafe_code) incompatible with previous forbid
+  --> $DIR/deny-inside-forbid-ignored.rs:12:17
+   |
+LL | #[forbid(unsafe_code)] // NO UNSAFE CODE IN HERE!!
+   |          ----------- `forbid` level set here
+...
+LL |         #[allow(unsafe_code)] // let's have some unsafe code in here
+   |                 ^^^^^^^^^^^ overruled by previous forbid
+
+error[E0453]: allow(unsafe_code) incompatible with previous forbid
+  --> $DIR/deny-inside-forbid-ignored.rs:12:17
+   |
+LL | #[forbid(unsafe_code)] // NO UNSAFE CODE IN HERE!!
+   |          ----------- `forbid` level set here
+...
+LL |         #[allow(unsafe_code)] // let's have some unsafe code in here
+   |                 ^^^^^^^^^^^ overruled by previous forbid
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: usage of an `unsafe` block
+  --> $DIR/deny-inside-forbid-ignored.rs:16:13
+   |
+LL |             unsafe { /* ≽^•⩊•^≼ */ }
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/deny-inside-forbid-ignored.rs:8:10
+   |
+LL | #[forbid(unsafe_code)] // NO UNSAFE CODE IN HERE!!
+   |          ^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0453`.

tests/ui/lint/deny-inside-forbid-ignored.cli_forbid_warnings.stderr

@@ -0,0 +1,35 @@
+error[E0453]: allow(unsafe_code) incompatible with previous forbid
+  --> $DIR/deny-inside-forbid-ignored.rs:12:17
+   |
+LL | #[forbid(unsafe_code)] // NO UNSAFE CODE IN HERE!!
+   |          ----------- `forbid` level set here
+...
+LL |         #[allow(unsafe_code)] // let's have some unsafe code in here
+   |                 ^^^^^^^^^^^ overruled by previous forbid
+
+error[E0453]: allow(unsafe_code) incompatible with previous forbid
+  --> $DIR/deny-inside-forbid-ignored.rs:12:17
+   |
+LL | #[forbid(unsafe_code)] // NO UNSAFE CODE IN HERE!!
+   |          ----------- `forbid` level set here
+...
+LL |         #[allow(unsafe_code)] // let's have some unsafe code in here
+   |                 ^^^^^^^^^^^ overruled by previous forbid
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: usage of an `unsafe` block
+  --> $DIR/deny-inside-forbid-ignored.rs:16:13
+   |
+LL |             unsafe { /* ≽^•⩊•^≼ */ }
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/deny-inside-forbid-ignored.rs:8:10
+   |
+LL | #[forbid(unsafe_code)] // NO UNSAFE CODE IN HERE!!
+   |          ^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0453`.

tests/ui/lint/deny-inside-forbid-ignored.rs

@@ -0,0 +1,20 @@
+//! Ensure that using deny inside forbid is treated as a no-op, and does not override the level to
+//! deny.
+
+//@ revisions: source_only cli_forbid cli_forbid_warnings
+//@[cli_forbid] compile-flags: -F unsafe_code
+//@[cli_forbid_warnings] compile-flags: -F warnings
+
+#[forbid(unsafe_code)] // NO UNSAFE CODE IN HERE!!
+fn main() {
+    #[deny(unsafe_code)] // m-m-maybe we can have unsafe code in here?
+    {
+        #[allow(unsafe_code)] // let's have some unsafe code in here
+        //~^ ERROR allow(unsafe_code) incompatible with previous forbid
+        //~| ERROR allow(unsafe_code) incompatible with previous forbid
+        {
+            unsafe { /* ≽^•⩊•^≼ */ }
+            //~^ ERROR usage of an `unsafe` block
+        }
+    }
+}