Rollup merge of #145206 - scrabsha:push-uxovoqzrxnlx, r=jdonszelmann

Port `#[custom_mir(..)]` to the new attribute system

r? ``````````@jdonszelmann``````````

2 files changed, 141 insertions, 0 deletions

diff --git a/compiler/rustc_attr_parsing/src/attributes/mod.rs b/compiler/rustc_attr_parsing/src/attributes/mod.rs
index ed5d1d92b8c..3d6e26a24b8 100644
--- a/compiler/rustc_attr_parsing/src/attributes/mod.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/mod.rs
@@ -43,6 +43,7 @@ pub(crate) mod no_implicit_prelude;
 pub(crate) mod non_exhaustive;
 pub(crate) mod path;
 pub(crate) mod proc_macro_attrs;
+pub(crate) mod prototype;
 pub(crate) mod repr;
 pub(crate) mod rustc_internal;
 pub(crate) mod semantics;
diff --git a/compiler/rustc_attr_parsing/src/attributes/prototype.rs b/compiler/rustc_attr_parsing/src/attributes/prototype.rs
new file mode 100644
index 00000000000..fb1e47298b4
--- /dev/null
+++ b/compiler/rustc_attr_parsing/src/attributes/prototype.rs
@@ -0,0 +1,140 @@
+//! Attributes that are only used on function prototypes.
+
+use rustc_feature::{AttributeTemplate, template};
+use rustc_hir::Target;
+use rustc_hir::attrs::{AttributeKind, MirDialect, MirPhase};
+use rustc_span::{Span, Symbol, sym};
+
+use super::{AttributeOrder, OnDuplicate};
+use crate::attributes::SingleAttributeParser;
+use crate::context::{AcceptContext, AllowedTargets, MaybeWarn, Stage};
+use crate::parser::ArgParser;
+
+pub(crate) struct CustomMirParser;
+
+impl<S: Stage> SingleAttributeParser<S> for CustomMirParser {
+    const PATH: &[rustc_span::Symbol] = &[sym::custom_mir];
+
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowList(&[MaybeWarn::Allow(Target::Fn)]);
+
+    const TEMPLATE: AttributeTemplate = template!(List: &[r#"dialect = "...", phase = "...""#]);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let Some(list) = args.list() else {
+            cx.expected_list(cx.attr_span);
+            return None;
+        };
+
+        let mut dialect = None;
+        let mut phase = None;
+        let mut failed = false;
+
+        for item in list.mixed() {
+            let Some(meta_item) = item.meta_item() else {
+                cx.expected_name_value(item.span(), None);
+                failed = true;
+                break;
+            };
+
+            if let Some(arg) = meta_item.word_is(sym::dialect) {
+                extract_value(cx, sym::dialect, arg, meta_item.span(), &mut dialect, &mut failed);
+            } else if let Some(arg) = meta_item.word_is(sym::phase) {
+                extract_value(cx, sym::phase, arg, meta_item.span(), &mut phase, &mut failed);
+            } else if let Some(word) = meta_item.path().word() {
+                let word = word.to_string();
+                cx.unknown_key(meta_item.span(), word, &["dialect", "phase"]);
+                failed = true;
+            } else {
+                cx.expected_name_value(meta_item.span(), None);
+                failed = true;
+            };
+        }
+
+        let dialect = parse_dialect(cx, dialect, &mut failed);
+        let phase = parse_phase(cx, phase, &mut failed);
+
+        if failed {
+            return None;
+        }
+
+        Some(AttributeKind::CustomMir(dialect, phase, cx.attr_span))
+    }
+}
+
+fn extract_value<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    key: Symbol,
+    arg: &ArgParser<'_>,
+    span: Span,
+    out_val: &mut Option<(Symbol, Span)>,
+    failed: &mut bool,
+) {
+    if out_val.is_some() {
+        cx.duplicate_key(span, key);
+        *failed = true;
+        return;
+    }
+
+    let Some(val) = arg.name_value() else {
+        cx.expected_single_argument(arg.span().unwrap_or(span));
+        *failed = true;
+        return;
+    };
+
+    let Some(value_sym) = val.value_as_str() else {
+        cx.expected_string_literal(val.value_span, Some(val.value_as_lit()));
+        *failed = true;
+        return;
+    };
+
+    *out_val = Some((value_sym, val.value_span));
+}
+
+fn parse_dialect<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    dialect: Option<(Symbol, Span)>,
+    failed: &mut bool,
+) -> Option<(MirDialect, Span)> {
+    let (dialect, span) = dialect?;
+
+    let dialect = match dialect {
+        sym::analysis => MirDialect::Analysis,
+        sym::built => MirDialect::Built,
+        sym::runtime => MirDialect::Runtime,
+
+        _ => {
+            cx.expected_specific_argument(span, vec!["analysis", "built", "runtime"]);
+            *failed = true;
+            return None;
+        }
+    };
+
+    Some((dialect, span))
+}
+
+fn parse_phase<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    phase: Option<(Symbol, Span)>,
+    failed: &mut bool,
+) -> Option<(MirPhase, Span)> {
+    let (phase, span) = phase?;
+
+    let phase = match phase {
+        sym::initial => MirPhase::Initial,
+        sym::post_cleanup => MirPhase::PostCleanup,
+        sym::optimized => MirPhase::Optimized,
+
+        _ => {
+            cx.expected_specific_argument(span, vec!["initial", "post-cleanup", "optimized"]);
+            *failed = true;
+            return None;
+        }
+    };
+
+    Some((phase, span))
+}