Rollup merge of rust-lang#76293 - Amjad50:incompatible_features_error…

…, r=lcnr

Implementation of incompatible features error

Proposal of a new error: Incompatible features

This error should happen if two features which are not compatible are used together.

For now the only incompatible features are `const_generics` and `min_const_generics`

fixes rust-lang#76280

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -608,6 +608,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
 
 pub fn check_crate(krate: &ast::Crate, sess: &Session) {
  maybe_stage_features(sess, krate);
+ check_incompatible_features(sess);
  let mut visitor = PostExpansionVisitor { sess, features: &sess.features_untracked() };
 
  let spans = sess.parse_sess.gated_spans.spans.borrow();
@@ -677,3 +678,36 @@ fn maybe_stage_features(sess: &Session, krate: &ast::Crate) {
  }
  }
 }
+
+fn check_incompatible_features(sess: &Session) {
+ let features = sess.features_untracked();
+
+ let declared_features = features
+ .declared_lang_features
+ .iter()
+ .copied()
+ .map(|(name, span, _)| (name, span))
+ .chain(features.declared_lib_features.iter().copied());
+
+ for (f1, f2) in rustc_feature::INCOMPATIBLE_FEATURES
+ .iter()
+ .filter(|&&(f1, f2)| features.enabled(f1) && features.enabled(f2))
+ {
+ if let Some((f1_name, f1_span)) = declared_features.clone().find(|(name, _)| name == f1) {
+ if let Some((f2_name, f2_span)) = declared_features.clone().find(|(name, _)| name == f2)
+ {
+ let spans = vec![f1_span, f2_span];
+ sess.struct_span_err(
+ spans.clone(),
+ &format!(
+ "features `{}` and `{}` are incompatible, using them at the same time \
+ is not allowed",
+ f1_name, f2_name
+ ),
+ )
+ .help("remove one of these features")
+ .emit();
+ }
+ }
+ }
+}

compiler/rustc_feature/src/active.rs

@@ -605,3 +605,8 @@ pub const INCOMPLETE_FEATURES: &[Symbol] = &[
  sym::lazy_normalization_consts,
  sym::specialization,
 ];
+
+/// Some features are not allowed to be used together at the same time, if
+/// the two are present, produce an error
+pub const INCOMPATIBLE_FEATURES: &[(Symbol, Symbol)] =
+ &[(sym::const_generics, sym::min_const_generics)];

compiler/rustc_feature/src/lib.rs

@@ -131,7 +131,7 @@ pub fn find_feature_issue(feature: Symbol, issue: GateIssue) -> Option<NonZeroU3
 }
 
 pub use accepted::ACCEPTED_FEATURES;
-pub use active::{Features, ACTIVE_FEATURES, INCOMPLETE_FEATURES};
+pub use active::{Features, ACTIVE_FEATURES, INCOMPATIBLE_FEATURES, INCOMPLETE_FEATURES};
 pub use builtin_attrs::{
  deprecated_attributes, find_gated_cfg, is_builtin_attr_name, AttributeGate, AttributeTemplate,
  AttributeType, BuiltinAttribute, GatedCfg, BUILTIN_ATTRIBUTES, BUILTIN_ATTRIBUTE_MAP,

src/test/ui/const-generics/min-and-full-same-time.rs

@@ -0,0 +1,7 @@
+#![feature(const_generics)]
+//~^ ERROR features `const_generics` and `min_const_generics` are incompatible
+#![allow(incomplete_features)]
+#![feature(min_const_generics)]
+
+
+fn main() {}

src/test/ui/const-generics/min-and-full-same-time.stderr

@@ -0,0 +1,13 @@
+error: features `const_generics` and `min_const_generics` are incompatible, using them at the same time is not allowed
+ --> $DIR/min-and-full-same-time.rs:1:12
+ |
+LL | #![feature(const_generics)]
+ | ^^^^^^^^^^^^^^
+...
+LL | #![feature(min_const_generics)]
+ | ^^^^^^^^^^^^^^^^^^
+ |
+ = help: remove one of these features
+
+error: aborting due to previous error
+