Auto merge of #129670 - est31:cfg_attr_crate_type_name_error, r=Urgau

Make deprecated_cfg_attr_crate_type_name a hard error

Turns the forward compatibility lint added by #83744 into a hard error, so now, while the `#![crate_name]` and `#![crate_type]` attributes are still allowed in raw form, they are now forbidden to be nested inside a `#![cfg_attr()]` attribute.

The following will now be an error:

```Rust
#![cfg_attr(foo, crate_name = "foobar")]
#![cfg_attr(foo, crate_type = "bin")]
```

This code will continue working and is not deprecated:

```Rust
#![crate_name = "foobar"]
#![crate_type = "lib"]
```

The reasoning for this is explained in #83744: it allows us to not have to cfg-expand in order to determine the crate's type and name.

As of filing the PR, exactly two years have passed since #99784 has been merged, which has turned the lint's default warning level into an error, so there has been ample time to move off the now-forbidden syntax.

cc #91632 - tracking issue for the lint

compiler/rustc_expand/messages.ftl

@@ -27,6 +27,12 @@ expand_collapse_debuginfo_illegal =
 expand_count_repetition_misplaced =
     `count` can not be placed inside the inner-most repetition
 
+expand_crate_name_in_cfg_attr =
+    `crate_name` within an `#![cfg_attr]` attribute is forbidden
+
+expand_crate_type_in_cfg_attr =
+    `crate_type` within an `#![cfg_attr]` attribute is forbidden
+
 expand_custom_attribute_panicked =
     custom attribute panicked
     .help = message: {$message}

compiler/rustc_expand/src/config.rs

@@ -23,8 +23,9 @@ use thin_vec::ThinVec;
 use tracing::instrument;
 
 use crate::errors::{
-    FeatureNotAllowed, FeatureRemoved, FeatureRemovedReason, InvalidCfg, MalformedFeatureAttribute,
+    CrateNameInCfgAttr, CrateTypeInCfgAttr, FeatureNotAllowed, FeatureRemoved,
-    MalformedFeatureAttributeHelp, RemoveExprNotSupported,
+    FeatureRemovedReason, InvalidCfg, MalformedFeatureAttribute, MalformedFeatureAttributeHelp,
+    RemoveExprNotSupported,
 };
 
 /// A folder that strips out items that do not belong in the current configuration.
@@ -360,20 +361,10 @@ impl<'a> StripUnconfigured<'a> {
             item_span,
         );
         if attr.has_name(sym::crate_type) {
-            self.sess.psess.buffer_lint(
+            self.sess.dcx().emit_err(CrateTypeInCfgAttr { span: attr.span });
-                rustc_lint_defs::builtin::DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-                attr.span,
-                ast::CRATE_NODE_ID,
-                BuiltinLintDiag::CrateTypeInCfgAttr,
-            );
         }
         if attr.has_name(sym::crate_name) {
-            self.sess.psess.buffer_lint(
+            self.sess.dcx().emit_err(CrateNameInCfgAttr { span: attr.span });
-                rustc_lint_defs::builtin::DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-                attr.span,
-                ast::CRATE_NODE_ID,
-                BuiltinLintDiag::CrateNameInCfgAttr,
-            );
         }
         attr
     }

compiler/rustc_expand/src/errors.rs

@@ -467,6 +467,20 @@ pub(crate) struct GlobDelegationOutsideImpls {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(expand_crate_name_in_cfg_attr)]
+pub(crate) struct CrateNameInCfgAttr {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(expand_crate_type_in_cfg_attr)]
+pub(crate) struct CrateTypeInCfgAttr {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(expand_glob_delegation_traitless_qpath)]
 pub(crate) struct GlobDelegationTraitlessQpath {

compiler/rustc_lint/messages.ftl

@@ -203,12 +203,6 @@ lint_confusable_identifier_pair = found both `{$existing_sym}` and `{$sym}` as i
     .current_use = this identifier can be confused with `{$existing_sym}`
     .other_use = other identifier used here
 
-lint_crate_name_in_cfg_attr_deprecated =
-    `crate_name` within an `#![cfg_attr]` attribute is deprecated
-
-lint_crate_type_in_cfg_attr_deprecated =
-    `crate_type` within an `#![cfg_attr]` attribute is deprecated
-
 lint_cstring_ptr = getting the inner pointer of a temporary `CString`
     .as_ptr_label = this pointer will be invalid
     .unwrap_label = this `CString` is deallocated at the end of the statement, bind it to a variable to extend its lifetime

compiler/rustc_lint/src/context/diagnostics.rs

@@ -400,12 +400,6 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
         BuiltinLintDiag::CfgAttrNoAttributes => {
             lints::CfgAttrNoAttributes.decorate_lint(diag);
         }
-        BuiltinLintDiag::CrateTypeInCfgAttr => {
-            lints::CrateTypeInCfgAttr.decorate_lint(diag);
-        }
-        BuiltinLintDiag::CrateNameInCfgAttr => {
-            lints::CrateNameInCfgAttr.decorate_lint(diag);
-        }
         BuiltinLintDiag::MissingFragmentSpecifier => {
             lints::MissingFragmentSpecifier.decorate_lint(diag);
         }

compiler/rustc_lint/src/lib.rs

@@ -569,6 +569,11 @@ fn register_builtins(store: &mut LintStore) {
         "converted into hard error, see RFC #3535 \
          <https://rust-lang.github.io/rfcs/3535-constants-in-patterns.html> for more information",
     );
+    store.register_removed(
+        "deprecated_cfg_attr_crate_type_name",
+        "converted into hard error, see issue #91632 \
+         <https://github.com/rust-lang/rust/issues/91632> for more information",
+    );
     store.register_removed(
         "pointer_structural_match",
         "converted into hard error, see RFC #3535 \

compiler/rustc_lint/src/lints.rs

@@ -2441,14 +2441,6 @@ pub(crate) struct DuplicateMacroAttribute;
 #[diag(lint_cfg_attr_no_attributes)]
 pub(crate) struct CfgAttrNoAttributes;
 
-#[derive(LintDiagnostic)]
-#[diag(lint_crate_type_in_cfg_attr_deprecated)]
-pub(crate) struct CrateTypeInCfgAttr;
-
-#[derive(LintDiagnostic)]
-#[diag(lint_crate_name_in_cfg_attr_deprecated)]
-pub(crate) struct CrateNameInCfgAttr;
-
 #[derive(LintDiagnostic)]
 #[diag(lint_missing_fragment_specifier)]
 pub(crate) struct MissingFragmentSpecifier;

compiler/rustc_lint_defs/src/builtin.rs

@@ -34,7 +34,6 @@ declare_lint_pass! {
         DEAD_CODE,
         DEPENDENCY_ON_UNIT_NEVER_TYPE_FALLBACK,
         DEPRECATED,
-        DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
         DEPRECATED_IN_FUTURE,
         DEPRECATED_SAFE_2024,
         DEPRECATED_WHERE_CLAUSE_LOCATION,
@@ -3144,42 +3143,6 @@ declare_lint! {
     "detects large moves or copies",
 }
 
-declare_lint! {
-    /// The `deprecated_cfg_attr_crate_type_name` lint detects uses of the
-    /// `#![cfg_attr(..., crate_type = "...")]` and
-    /// `#![cfg_attr(..., crate_name = "...")]` attributes to conditionally
-    /// specify the crate type and name in the source code.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,compile_fail
-    /// #![cfg_attr(debug_assertions, crate_type = "lib")]
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    ///
-    /// ### Explanation
-    ///
-    /// The `#![crate_type]` and `#![crate_name]` attributes require a hack in
-    /// the compiler to be able to change the used crate type and crate name
-    /// after macros have been expanded. Neither attribute works in combination
-    /// with Cargo as it explicitly passes `--crate-type` and `--crate-name` on
-    /// the commandline. These values must match the value used in the source
-    /// code to prevent an error.
-    ///
-    /// To fix the warning use `--crate-type` on the commandline when running
-    /// rustc instead of `#![cfg_attr(..., crate_type = "...")]` and
-    /// `--crate-name` instead of `#![cfg_attr(..., crate_name = "...")]`.
-    pub DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-    Deny,
-    "detects usage of `#![cfg_attr(..., crate_type/crate_name = \"...\")]`",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
-        reference: "issue #91632 <https://github.com/rust-lang/rust/issues/91632>",
-    };
-}
-
 declare_lint! {
     /// The `unexpected_cfgs` lint detects unexpected conditional compilation conditions.
     ///

compiler/rustc_lint_defs/src/lib.rs

@@ -720,8 +720,6 @@ pub enum BuiltinLintDiag {
     UnnameableTestItems,
     DuplicateMacroAttribute,
     CfgAttrNoAttributes,
-    CrateTypeInCfgAttr,
-    CrateNameInCfgAttr,
     MissingFragmentSpecifier,
     MetaVariableStillRepeating(MacroRulesNormalizedIdent),
     MetaVariableWrongOperator,

tests/ui/cfg/crate-attributes-using-cfg_attr.rs

@@ -3,13 +3,9 @@
 
 #![cfg_attr(foo, crate_type="bin")]
 //~^ERROR `crate_type` within
-//~| WARN this was previously accepted
 //~|ERROR `crate_type` within
-//~| WARN this was previously accepted
 #![cfg_attr(foo, crate_name="bar")]
 //~^ERROR `crate_name` within
-//~| WARN this was previously accepted
 //~|ERROR `crate_name` within
-//~| WARN this was previously accepted
 
 fn main() {}

tests/ui/cfg/crate-attributes-using-cfg_attr.stderr

@@ -0,0 +1,30 @@
+error: `crate_type` within an `#![cfg_attr]` attribute is forbidden
+  --> $DIR/crate-attributes-using-cfg_attr.rs:4:18
+   |
+LL | #![cfg_attr(foo, crate_type="bin")]
+   |                  ^^^^^^^^^^^^^^^^
+
+error: `crate_name` within an `#![cfg_attr]` attribute is forbidden
+  --> $DIR/crate-attributes-using-cfg_attr.rs:7:18
+   |
+LL | #![cfg_attr(foo, crate_name="bar")]
+   |                  ^^^^^^^^^^^^^^^^
+
+error: `crate_type` within an `#![cfg_attr]` attribute is forbidden
+  --> $DIR/crate-attributes-using-cfg_attr.rs:4:18
+   |
+LL | #![cfg_attr(foo, crate_type="bin")]
+   |                  ^^^^^^^^^^^^^^^^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: `crate_name` within an `#![cfg_attr]` attribute is forbidden
+  --> $DIR/crate-attributes-using-cfg_attr.rs:7:18
+   |
+LL | #![cfg_attr(foo, crate_name="bar")]
+   |                  ^^^^^^^^^^^^^^^^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: aborting due to 4 previous errors
+

tests/ui/cfg/future-compat-crate-attributes-using-cfg_attr.stderr

@@ -1,41 +0,0 @@
-error: `crate_type` within an `#![cfg_attr]` attribute is deprecated
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:4:18
-   |
-LL | #![cfg_attr(foo, crate_type="bin")]
-   |                  ^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #91632 <https://github.com/rust-lang/rust/issues/91632>
-   = note: `#[deny(deprecated_cfg_attr_crate_type_name)]` on by default
-
-error: `crate_name` within an `#![cfg_attr]` attribute is deprecated
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:9:18
-   |
-LL | #![cfg_attr(foo, crate_name="bar")]
-   |                  ^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #91632 <https://github.com/rust-lang/rust/issues/91632>
-
-error: `crate_type` within an `#![cfg_attr]` attribute is deprecated
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:4:18
-   |
-LL | #![cfg_attr(foo, crate_type="bin")]
-   |                  ^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #91632 <https://github.com/rust-lang/rust/issues/91632>
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: `crate_name` within an `#![cfg_attr]` attribute is deprecated
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:9:18
-   |
-LL | #![cfg_attr(foo, crate_name="bar")]
-   |                  ^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #91632 <https://github.com/rust-lang/rust/issues/91632>
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 4 previous errors
-