Rust: move to Label<T> and mark unsafety of from_untyped

misc/codegen/generators/rustgen.py

@@ -20,7 +20,7 @@ def _get_type(t: str) -> str:
         case "int":
             return "usize"
         case _ if t[0].isupper():
-            return f"{t}TrapLabel"
+            return f"trap::Label<{t}>"
         case "boolean":
             assert False, "boolean unsupported"
         case _:

misc/codegen/templates/rust_classes.mustache

@@ -5,33 +5,6 @@
 use crate::trap;
 {{#classes}}
 
-#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
-pub struct {{name}}TrapLabel(trap::UntypedLabel);
-
-impl From<trap::UntypedLabel> for {{name}}TrapLabel {
-    fn from(value: trap::UntypedLabel) -> Self {
-        Self(value)
-    }
-}
-
-impl  From<{{name}}TrapLabel> for trap::TrapId<{{name}}> {
-    fn from(value: {{name}}TrapLabel) -> Self {
-        Self::Label(value)
-    }
-}
-
-impl trap::Label for {{name}}TrapLabel {
-    fn as_untyped(&self) -> trap::UntypedLabel {
-        self.0
-    }
-}
-
-impl From<{{name}}TrapLabel> for trap::Arg {
-    fn from(value: {{name}}TrapLabel) -> Self {
-        value.0.into()
-    }
-}
-
 {{#table_name}}
 #[derive(Debug)]
 pub struct {{name}} {
@@ -48,7 +21,7 @@ impl trap::TrapEntry for {{name}} {
         std::mem::replace(&mut self.id, trap::TrapId::Star)
     }
 
-    fn emit(self, id: Self::Label, out: &mut trap::Writer) {
+    fn emit(self, id: trap::Label<Self>, out: &mut trap::Writer) {
         {{#single_field_entries}}
         out.add_tuple("{{table_name}}", vec![id.into(){{#fields}}, self.{{field_name}}.into(){{/fields}}]);
         {{/single_field_entries}}
@@ -87,18 +60,14 @@ pub struct {{name}} {
     unused: ()
 }
 {{/table_name}}
-
-impl trap::TrapClass for {{name}} {
-    type Label = {{name}}TrapLabel;
-}
-{{/classes}}
-
-// Conversions
-{{#classes}}
 {{#ancestors}}
-impl From<{{name}}TrapLabel> for {{.}}TrapLabel {
-    fn from(value: {{name}}TrapLabel) -> Self {
-        value.0.into()
+
+impl From<trap::Label<{{name}}>> for trap::Label<{{.}}> {
+    fn from(value: trap::Label<{{name}}>) -> Self {
+        // SAFETY: this is safe because in the dbscheme {{name}} is a subclass of {{.}}
+        unsafe {
+            Self::from_untyped(value.as_untyped())
+        }
     }
 }
 {{/ancestors}}

rust/extractor/src/generated/.generated.list

@@ -1,2 +1,2 @@
 mod.rs 7cdfedcd68cf8e41134daf810c1af78624082b0c3e8be6570339b1a69a5d457e 7cdfedcd68cf8e41134daf810c1af78624082b0c3e8be6570339b1a69a5d457e
-top.rs e06dc90de4abd57719786fd5e49e6ea3089ec3ec167c64446e25d95a16b1714c e06dc90de4abd57719786fd5e49e6ea3089ec3ec167c64446e25d95a16b1714c
+top.rs 775cb04552f9242ff999b279a375f7a446124f4ef28668e42496751bf69e7dd3 775cb04552f9242ff999b279a375f7a446124f4ef28668e42496751bf69e7dd3

rust/extractor/src/translate.rs

@@ -1,5 +1,5 @@
 use crate::archive::Archiver;
-use crate::trap::{AsTrapKeyPart, Label, TrapFile, TrapId};
+use crate::trap::{AsTrapKeyPart, Label, TrapEntry, TrapFile, TrapId};
 use crate::{generated, trap_key};
 use codeql_extractor::trap;
 use ra_ap_hir::db::{DefDatabase, InternDatabase};
@@ -71,9 +71,9 @@ impl CrateTranslator<'_> {
         })
     }
 
-    fn emit_location_for_ast_ptr<L: Label, T: AstNode>(
+    fn emit_location_for_ast_ptr<E: TrapEntry, T: AstNode>(
         &mut self,
-        label: L,
+        label: Label<E>,
         source: ra_ap_hir::InFile<ra_ap_syntax::AstPtr<T>>,
     ) {
         source
@@ -89,7 +89,7 @@ impl CrateTranslator<'_> {
 
     fn emit_location_for_expr(
         &mut self,
-        label: generated::ElementTrapLabel, // TODO: should be ExprTrapLabel
+        label: Label<generated::Element>, // TODO: should be ExprTrapLabel
         expr: ra_ap_hir_def::hir::ExprId,
         source_map: &BodySourceMap,
     ) {
@@ -101,7 +101,7 @@ impl CrateTranslator<'_> {
     fn emit_location_for_pat(
         &mut self,
         // should be Pat, but we're using for other entities for now
-        label: generated::ElementTrapLabel,
+        label: Label<generated::Element>,
         pat_id: ra_ap_hir_def::hir::PatId,
         source_map: &BodySourceMap,
     ) {
@@ -115,7 +115,7 @@ impl CrateTranslator<'_> {
         pat: &ra_ap_hir_def::hir::LiteralOrConst,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::PatTrapLabel {
+    ) -> Label<generated::Pat> {
         match pat {
             ra_ap_hir_def::hir::LiteralOrConst::Literal(_literal) => {
                 let expr = self.trap.emit(generated::LiteralExpr { id: TrapId::Star });
@@ -132,9 +132,9 @@ impl CrateTranslator<'_> {
         }
     }
 
-    fn emit_location_for_label<T: Label>(
+    fn emit_location_for_label<E: TrapEntry>(
         &mut self,
-        label: T,
+        label: Label<E>,
         label_id: ra_ap_hir_def::hir::LabelId,
         source_map: &BodySourceMap,
     ) {
@@ -144,7 +144,7 @@ impl CrateTranslator<'_> {
             self.emit_location_for_ast_ptr(label, source)
         }
     }
-    fn emit_location<L: Label, T: HasSource>(&mut self, label: L, entity: T)
+    fn emit_location<E: TrapEntry, T: HasSource>(&mut self, label: Label<E>, entity: T)
     where
         T::Ast: AstNode,
     {
@@ -157,9 +157,9 @@ impl CrateTranslator<'_> {
                 self.emit_location_for_textrange(label, data, range);
             });
     }
-    fn emit_location_for_textrange<L: Label>(
+    fn emit_location_for_textrange<E: TrapEntry>(
         &mut self,
-        label: L,
+        label: Label<E>,
         data: FileData,
         range: TextRange,
     ) {
@@ -177,7 +177,7 @@ impl CrateTranslator<'_> {
         label_id: LabelId,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::LabelTrapLabel {
+    ) -> Label<generated::Label> {
         let label = &body.labels[label_id];
         let ret = self.trap.emit(generated::Label {
             id: TrapId::Star,
@@ -187,11 +187,11 @@ impl CrateTranslator<'_> {
         ret
     }
 
-    fn emit_unimplemented(&mut self) -> generated::UnimplementedTrapLabel {
+    fn emit_unimplemented(&mut self) -> Label<generated::Unimplemented> {
         self.trap
             .emit(generated::Unimplemented { id: TrapId::Star })
     }
-    fn emit_path(&mut self, _path: &Path) -> generated::UnimplementedTrapLabel {
+    fn emit_path(&mut self, _path: &Path) -> Label<generated::Unimplemented> {
         self.emit_unimplemented()
     }
 
@@ -200,7 +200,7 @@ impl CrateTranslator<'_> {
         field_pat: &RecordFieldPat,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::RecordFieldPatTrapLabel {
+    ) -> Label<generated::RecordFieldPat> {
         let RecordFieldPat { name, pat } = field_pat;
         let pat_label = self.emit_pat(*pat, body, source_map);
         let ret = self.trap.emit(generated::RecordFieldPat {
@@ -217,7 +217,7 @@ impl CrateTranslator<'_> {
         field_expr: &RecordLitField,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::RecordLitFieldTrapLabel {
+    ) -> Label<generated::RecordLitField> {
         let RecordLitField { name, expr } = field_expr;
         let expr_label = self.emit_expr(*expr, body, source_map);
         let ret = self.trap.emit(generated::RecordLitField {
@@ -234,9 +234,9 @@ impl CrateTranslator<'_> {
         pat_id: PatId,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::PatTrapLabel {
+    ) -> Label<generated::Pat> {
         let pat = &body.pats[pat_id];
-        let ret: generated::PatTrapLabel = match pat {
+        let ret: Label<generated::Pat> = match pat {
             ra_ap_hir_def::hir::Pat::Missing => self
                 .trap
                 .emit(generated::MissingPat { id: TrapId::Star })
@@ -407,7 +407,7 @@ impl CrateTranslator<'_> {
         self.emit_location_for_pat(ret.into(), pat_id, source_map);
         ret
     }
-    fn emit_type_ref(&mut self, _type_ref: &TypeRef) -> generated::TypeRefTrapLabel {
+    fn emit_type_ref(&mut self, _type_ref: &TypeRef) -> Label<generated::TypeRef> {
         self.emit_unimplemented().into()
     }
     fn emit_match_arm(
@@ -415,7 +415,7 @@ impl CrateTranslator<'_> {
         arm: &MatchArm,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::MatchArmTrapLabel {
+    ) -> Label<generated::MatchArm> {
         let pat = self.emit_pat(arm.pat, body, source_map);
         let guard = arm.guard.map(|g| self.emit_expr(g, body, source_map));
         let expr = self.emit_expr(arm.expr, body, source_map);
@@ -434,7 +434,7 @@ impl CrateTranslator<'_> {
         stmt: &Statement,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::StmtTrapLabel {
+    ) -> Label<generated::Stmt> {
         match stmt {
             Statement::Let {
                 pat,
@@ -483,9 +483,9 @@ impl CrateTranslator<'_> {
         expr_id: ExprId,
         body: &Body,
         source_map: &BodySourceMap,
-    ) -> generated::ExprTrapLabel {
+    ) -> Label<generated::Expr> {
         let expr = &body[expr_id];
-        let ret: generated::ExprTrapLabel = match expr {
+        let ret: Label<generated::Expr> = match expr {
             ra_ap_hir_def::hir::Expr::Missing => self
                 .trap
                 .emit(generated::MissingExpr { id: TrapId::Star })
@@ -976,11 +976,11 @@ impl CrateTranslator<'_> {
 
     fn emit_definition(
         &mut self,
-        module_label: generated::ModuleTrapLabel,
+        module_label: Label<generated::Module>,
         id: ModuleDef,
-        labels: &mut Vec<generated::DeclarationTrapLabel>,
+        labels: &mut Vec<Label<generated::Declaration>>,
     ) {
-        let label: generated::DeclarationTrapLabel = match id {
+        let label: Label<generated::Declaration> = match id {
             ModuleDef::Module(_) => self.emit_unimplemented().into(),
             ModuleDef::Function(function) => {
                 let def: ra_ap_hir::DefWithBody = function.into();
@@ -1050,7 +1050,7 @@ impl CrateTranslator<'_> {
         labels.push(label);
     }
 
-    fn emit_module(&mut self, label: generated::ModuleTrapLabel, module: Module) {
+    fn emit_module(&mut self, label: Label<generated::Module>, module: Module) {
         let mut children = Vec::new();
         for id in module.declarations(self.db) {
             self.emit_definition(label, id, &mut children);
@@ -1063,7 +1063,7 @@ impl CrateTranslator<'_> {
 
     pub fn emit_crate(&mut self) -> std::io::Result<()> {
         self.emit_file(self.krate.root_file(self.db));
-        let mut map = HashMap::<Module, generated::ModuleTrapLabel>::new();
+        let mut map = HashMap::<Module, Label<generated::Module>>::new();
         for module in self.krate.modules(self.db) {
             let mut key = String::new();
             if let Some(parent) = module.parent(self.db) {

rust/extractor/src/trap.rs

@@ -6,10 +6,11 @@ use ra_ap_ide_db::line_index::LineCol;
 use std::ffi::OsString;
 use std::fmt::Debug;
 use std::hash::Hash;
+use std::marker::PhantomData;
 use std::path::{Path, PathBuf};
 
 pub use trap::Label as UntypedLabel;
-pub use trap::{Arg, Writer};
+pub use trap::Writer;
 
 //TODO: typed labels
 pub trait AsTrapKeyPart {
@@ -38,7 +39,7 @@ impl AsTrapKeyPart for &str {
 pub enum TrapId<T: TrapEntry> {
     Star,
     Key(String),
-    Label(T::Label),
+    Label(Label<T>),
 }
 
 impl<T: TrapEntry> From<String> for TrapId<T> {
@@ -53,9 +54,9 @@ impl<T: TrapEntry> From<&str> for TrapId<T> {
     }
 }
 
-impl<T: TrapEntry> From<UntypedLabel> for TrapId<T> {
-    fn from(value: UntypedLabel) -> Self {
-        TrapId::Label(value.into())
+impl<T: TrapEntry> From<Label<T>> for TrapId<T> {
+    fn from(value: Label<T>) -> Self {
+        Self::Label(value)
     }
 }
 
@@ -70,36 +71,67 @@ macro_rules! trap_key {
     }};
 }
 
-pub trait Label: From<UntypedLabel> + Clone + Debug + Hash + Into<Arg> {
-    fn as_untyped(&self) -> UntypedLabel;
+#[derive(Debug, Ord, PartialOrd, Eq, PartialEq, Hash)]
+pub struct Label<T: TrapEntry> {
+    untyped: UntypedLabel,
+    phantom: PhantomData<T>, // otherwise Rust wants `T` to be used
+}
 
+// not deriving `Clone` and `Copy` because they require `T: Clone` and `T: Copy` respectively,
+// even if `T` is not actually part of the fields.
+// see https://github.com/rust-lang/rust/issues/108894
+impl<T: TrapEntry> Clone for Label<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<T: TrapEntry> Copy for Label<T> {}
+
+impl<T: TrapEntry> Label<T> {
+    pub fn as_untyped(&self) -> UntypedLabel {
+        self.untyped
+    }
+
+    /// # Safety
+    /// The user must make sure the label respects TRAP typing
+    pub unsafe fn from_untyped(untyped: UntypedLabel) -> Self {
+        Self {
+            untyped,
+            phantom: PhantomData,
+        }
+    }
+}
+
+impl<T: TrapEntry> AsTrapKeyPart for Label<T> {
     fn as_key_part(&self) -> String {
         self.as_untyped().as_key_part()
     }
 }
 
-pub trait TrapClass {
-    type Label: Label;
+impl<T: TrapEntry> From<Label<T>> for trap::Arg {
+    fn from(value: Label<T>) -> Self {
+        trap::Arg::Label(value.as_untyped())
+    }
 }
 
-pub trait TrapEntry: std::fmt::Debug + TrapClass + Sized {
+pub trait TrapEntry: std::fmt::Debug + Sized {
     fn class_name() -> &'static str;
-
     fn extract_id(&mut self) -> TrapId<Self>;
-    fn emit(self, id: Self::Label, out: &mut trap::Writer);
+    fn emit(self, id: Label<Self>, out: &mut Writer);
 }
 
 pub struct TrapFile {
     path: PathBuf,
-    writer: trap::Writer,
+    writer: Writer,
     compression: Compression,
 }
 
 impl TrapFile {
-    pub fn emit_location<L: Label>(
+    pub fn emit_location<T: TrapEntry>(
         &mut self,
         file_label: UntypedLabel,
-        entity_label: L,
+        entity_label: Label<T>,
         start: LineCol,
         end: LineCol,
     ) {
@@ -127,21 +159,28 @@ impl TrapFile {
         extractor::populate_file(&mut self.writer, absolute_path)
     }
 
-    pub fn label<T: TrapEntry>(&mut self, id: TrapId<T>) -> T::Label {
+    pub fn label<T: TrapEntry>(&mut self, id: TrapId<T>) -> Label<T> {
         match id {
-            TrapId::Star => self.writer.fresh_id().into(),
-            TrapId::Key(s) => self
-                .writer
-                .global_id(&format!("{},{}", T::class_name(), s))
-                .0
-                .into(),
+            TrapId::Star => {
+                let untyped = self.writer.fresh_id();
+                // SAFETY: a `*` trap id is always safe for typing
+                unsafe { Label::from_untyped(untyped) }
+            }
+            TrapId::Key(s) => {
+                let untyped = self
+                    .writer
+                    .global_id(&format!("{},{}", T::class_name(), s))
+                    .0;
+                // SAFETY: using type names as prefixes avoids labels having a conflicting type
+                unsafe { Label::from_untyped(untyped) }
+            }
             TrapId::Label(l) => l,
         }
     }
 
-    pub fn emit<T: TrapEntry>(&mut self, mut e: T) -> T::Label {
+    pub fn emit<T: TrapEntry>(&mut self, mut e: T) -> Label<T> {
         let label = self.label(e.extract_id());
-        e.emit(label.clone(), &mut self.writer);
+        e.emit(label, &mut self.writer);
         label
     }