[rust][sema] Bubble unresolved references (for hoisting)
This is a precursor to adding support for hoisting in semantic analysis. Previously when we encountered an unknown reference we immediately reported an error. But hoisted variables may be referenced before they're defined, so we don't know for sure when we see an unknown variable if its actually unbound or not. This PR adds the first part of hoistingn support: rather than immediately report an error when encountering an unbound variable we store it in a list of unresolved references on the current scope. As we close each scope we recheck and see if the variable can now be resolved. If yes we record that, otherwise we bubble up the unresolved reference to the parent scope (and try again there). The next PR(s) will handle hoisting of `var` and other syntax to the apropriate nearest scope boundary (function/module).
Joe Savona committed
Aug 14, 2023 at 10:08 UTC
011570a0785d4d2f0fd23dd5eae37ac797ce882b
4 files changed
+221
-12
compiler/forget/crates/forget_semantic_analysis/src/analyzer.rs
+48
-11
@@ -86,10 +86,9 @@ impl Analyzer {
86
where
87
F: FnMut(&mut Self) -> (),
88
{
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- let scope = self.manager.add_scope(self.current, kind);
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- let previous = std::mem::replace(&mut self.current, scope);
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+ let scope = self.enter_scope(kind);
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f(self);
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- let scope = std::mem::replace(&mut self.current, previous);
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+ self.close_scope(scope);
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scope
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}
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@@ -101,8 +100,26 @@ impl Analyzer {
100
101
fn close_scope(&mut self, id: ScopeId) {
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assert_eq!(self.current, id, "Mismatched enter_scope/close_scope");
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- let scope = self.manager.scope(self.current);
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- self.current = scope.parent.unwrap();
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+ let scope = self.manager.mut_scope(self.current);
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+ let parent = scope.parent.unwrap();
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+ let unresolved = std::mem::take(&mut scope.unresolved);
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+ drop(scope);
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+ self.current = parent;
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+
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+ // Lookup unresolved nodes from the child scope in the (now-current) parent scope
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+ for reference in unresolved {
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+ if let Some(declaration) = self
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+ .manager
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+ .lookup_declaration(reference.scope, &reference.name)
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+ {
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+ let id =
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+ self.manager
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+ .add_reference(reference.scope, reference.kind, declaration.id);
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+ self.manager.node_references.insert(reference.ast, id);
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+ } else {
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+ self.manager.push_unresolved_reference(parent, reference);
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+ }
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+ }
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}
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fn visit_function<T: IntoFunction>(&mut self, node: &T) {
@@ -157,10 +174,8 @@ impl Analyzer {
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.add_reference(self.current, kind, declaration.id);
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self.manager.node_references.insert(ast, id);
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} else {
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- // Oops, undefined variable
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self.manager
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- .diagnostics
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- .push(Diagnostic::invalid_syntax("Undefined variable", range));
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+ .add_unresolved_reference(self.current, ast, name.to_string(), kind, range);
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}
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}
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@@ -201,9 +216,13 @@ impl Analyzer {
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.node_references
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.insert(AstNode::from(ast), reference);
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} else {
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- self.manager
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- .diagnostics
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- .push(Diagnostic::invalid_syntax("Undefined variable", ast.range));
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+ self.manager.add_unresolved_reference(
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+ self.current,
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+ AstNode::from(ast),
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+ ast.name.clone(),
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+ ReferenceKind::ReadWrite,
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+ ast.range,
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+ );
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}
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}
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}
@@ -616,6 +635,24 @@ impl Visitor for Analyzer {
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self.visit_module_item(item);
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}
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}
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+ let scope = self.manager.mut_scope(self.current);
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+ let unresolved = std::mem::take(&mut scope.unresolved);
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+ for reference in unresolved {
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+ if let Some(declaration) = self
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+ .manager
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+ .lookup_declaration(reference.scope, &reference.name)
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+ {
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+ let id =
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+ self.manager
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+ .add_reference(reference.scope, reference.kind, declaration.id);
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+ self.manager.node_references.insert(reference.ast, id);
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+ } else {
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+ self.manager.diagnostics.push(Diagnostic::invalid_syntax(
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+ "Undefined variable",
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+ reference.range,
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+ ));
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+ }
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+ }
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}
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fn visit_property(&mut self, ast: &forget_estree::Property) {
compiler/forget/crates/forget_semantic_analysis/src/scope_manager.rs
+43
-1
@@ -1,6 +1,7 @@
1
use forget_diagnostics::Diagnostic;
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use forget_estree::{
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- BreakStatement, ContinueStatement, ESTreeNode, LabeledStatement, VariableDeclarationKind,
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+ BreakStatement, ContinueStatement, ESTreeNode, LabeledStatement, SourceRange,
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+ VariableDeclarationKind,
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};
6
use forget_utils::PointerAddress;
7
use indexmap::IndexMap;
@@ -43,6 +44,7 @@ impl ScopeManager {
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declarations: Default::default(),
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references: Default::default(),
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children: Default::default(),
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+ unresolved: Default::default(),
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}],
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labels: Default::default(),
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declarations: Default::default(),
@@ -75,6 +77,10 @@ impl ScopeManager {
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&self.scopes[id.0]
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}
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+ pub fn mut_scope(&mut self, id: ScopeId) -> &mut Scope {
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+ &mut self.scopes[id.0]
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+ }
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+
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pub fn is_descendant_of(&self, maybe_descendant: ScopeId, maybe_ancestor: ScopeId) -> bool {
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let mut current = maybe_descendant;
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loop {
@@ -192,6 +198,7 @@ impl ScopeManager {
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declarations: Default::default(),
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references: Default::default(),
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children: Default::default(),
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+ unresolved: Default::default(),
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});
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self.scopes[parent.0].children.push(id);
204
id
@@ -252,6 +259,31 @@ impl ScopeManager {
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self.scopes[scope.0].references.push(id);
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id
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}
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+
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+ pub(crate) fn push_unresolved_reference(
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+ &mut self,
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+ scope: ScopeId,
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+ reference: UnresolvedReference,
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+ ) {
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+ self.scopes[scope.0].unresolved.push(reference);
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+ }
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+
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+ pub(crate) fn add_unresolved_reference(
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+ &mut self,
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+ scope: ScopeId,
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+ ast: AstNode,
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+ name: String,
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+ kind: ReferenceKind,
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+ range: Option<SourceRange>,
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+ ) {
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+ self.scopes[scope.0].unresolved.push(UnresolvedReference {
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+ ast,
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+ scope,
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+ name,
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+ kind,
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+ range,
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+ });
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+ }
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}
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#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Copy, Clone)]
@@ -286,6 +318,16 @@ pub struct Scope {
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pub declarations: IndexMap<String, DeclarationId>,
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pub references: Vec<ReferenceId>,
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pub children: Vec<ScopeId>,
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+ pub unresolved: Vec<UnresolvedReference>,
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+}
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+
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+#[derive(Debug, Clone)]
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+pub struct UnresolvedReference {
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+ pub scope: ScopeId,
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+ pub ast: AstNode,
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+ pub name: String,
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+ pub kind: ReferenceKind,
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+ pub range: Option<SourceRange>,
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}
332
333
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Copy, Clone)]
compiler/forget/crates/forget_semantic_analysis/tests/fixtures/let-const-hoisting.js
new
+8
@@ -0,0 +1,8 @@
1
+function Component() {
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+ function foo() {
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+ a;
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+ b;
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+ }
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+ let a;
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+ const b = true;
8
+}
compiler/forget/crates/forget_semantic_analysis/tests/snapshots/analysis_test__fixtures@let-const-hoisting.js.snap
new
+122
@@ -0,0 +1,122 @@
1
+---
2
+source: crates/forget_semantic_analysis/tests/analysis_test.rs
3
+expression: "format!(\"Input:\\n{input}\\n\\nAnalysis:\\n{output}\")"
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+input_file: crates/forget_semantic_analysis/tests/fixtures/let-const-hoisting.js
5
+---
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+Input:
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+function Component() {
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+ function foo() {
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+ a;
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+ b;
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+ }
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+ let a;
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+ const b = true;
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+}
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+
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+
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+Analysis:
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+Scope {
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+ id: ScopeId(
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+ 0,
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+ ),
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+ kind: Global,
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+ declarations: {},
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+ references: [],
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+ children: [
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+ Scope {
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+ id: ScopeId(
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+ 1,
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+ ),
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+ kind: Module,
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+ declarations: {
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+ "Component": Declaration {
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+ id: DeclarationId(
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+ 0,
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+ ),
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+ kind: FunctionDeclaration,
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+ scope: ScopeId(
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+ 1,
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+ ),
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+ },
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+ },
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+ references: [],
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+ children: [
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+ Scope {
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+ id: ScopeId(
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+ 2,
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+ ),
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+ kind: Function,
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+ declarations: {
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+ "foo": Declaration {
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+ id: DeclarationId(
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+ 1,
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+ ),
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+ kind: FunctionDeclaration,
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+ scope: ScopeId(
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+ 2,
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+ ),
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+ },
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+ "a": Declaration {
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+ id: DeclarationId(
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+ 2,
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+ ),
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+ kind: Let,
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+ scope: ScopeId(
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+ 2,
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+ ),
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+ },
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+ "b": Declaration {
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+ id: DeclarationId(
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+ 3,
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+ ),
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+ kind: Const,
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+ scope: ScopeId(
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+ 2,
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+ ),
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+ },
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+ },
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+ references: [],
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+ children: [
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+ Scope {
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+ id: ScopeId(
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+ 3,
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+ ),
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+ kind: Function,
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+ declarations: {},
86
+ references: [
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+ Reference {
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+ id: ReferenceId(
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+ 0,
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+ ),
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+ kind: Read,
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+ declaration: DeclarationId(
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+ 2,
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+ ),
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+ declaration (name): "a",
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+ scope: ScopeId(
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+ 3,
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+ ),
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+ },
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+ Reference {
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+ id: ReferenceId(
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+ 1,
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+ ),
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+ kind: Read,
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+ declaration: DeclarationId(
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+ 3,
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+ ),
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+ declaration (name): "b",
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+ scope: ScopeId(
110
+ 3,
111
+ ),
112
+ },
113
+ ],
114
+ children: [],
115
+ },
116
+ ],
117
+ },
118
+ ],
119
+ },
120
+ ],
121
+}
122
+