diff options
| -rw-r--r-- | tvix/eval/src/compiler.rs | 69 | ||||
| -rw-r--r-- | tvix/eval/src/warnings.rs | 1 |
2 files changed, 50 insertions, 20 deletions
diff --git a/tvix/eval/src/compiler.rs b/tvix/eval/src/compiler.rs index 577578a936e6..cc1d3dac8c6c 100644 --- a/tvix/eval/src/compiler.rs +++ b/tvix/eval/src/compiler.rs @@ -40,12 +40,18 @@ struct Local { // of `let`-expressions. name: String, + // Syntax node at which this local was declared. + node: Option<rnix::SyntaxNode>, + // Scope depth of this local. depth: usize, // Phantom locals are not actually accessible by users (e.g. // intermediate values used for `with`). phantom: bool, + + // Is this local known to have been used at all? + used: bool, } /// Represents a stack offset containing keys which are currently @@ -599,7 +605,10 @@ impl Compiler { self.compile(from.expr().unwrap()); self.emit_literal_ident(&ident); self.chunk.push_op(OpCode::OpAttrsSelect); - self.declare_local(ident.ident_token().unwrap().text()); + self.declare_local( + ident.syntax().clone(), + ident.ident_token().unwrap().text(), + ); } } } @@ -619,7 +628,10 @@ impl Compiler { } self.compile(entry.value().unwrap()); - self.declare_local(path.pop().unwrap()); + self.declare_local( + entry.attrpath().unwrap().syntax().clone(), + path.pop().unwrap(), + ); } // Deal with the body, then clean up the locals afterwards. @@ -719,22 +731,21 @@ impl Compiler { } fn end_scope(&mut self) { - let mut scope = &mut self.scope; - debug_assert!(scope.scope_depth != 0, "can not end top scope"); + debug_assert!(self.scope.scope_depth != 0, "can not end top scope"); // If this scope poisoned any builtins or special identifiers, // they need to be reset. - if scope.poisoned_true == scope.scope_depth { - scope.poisoned_true = 0; + if self.scope.poisoned_true == self.scope.scope_depth { + self.scope.poisoned_true = 0; } - if scope.poisoned_false == scope.scope_depth { - scope.poisoned_false = 0; + if self.scope.poisoned_false == self.scope.scope_depth { + self.scope.poisoned_false = 0; } - if scope.poisoned_null == scope.scope_depth { - scope.poisoned_null = 0; + if self.scope.poisoned_null == self.scope.scope_depth { + self.scope.poisoned_null = 0; } - scope.scope_depth -= 1; + self.scope.scope_depth -= 1; // When ending a scope, all corresponding locals need to be // removed, but the value of the body needs to remain on the @@ -743,29 +754,42 @@ impl Compiler { // TL;DR - iterate from the back while things belonging to the // ended scope still exist. - while !scope.locals.is_empty() - && scope.locals[scope.locals.len() - 1].depth > scope.scope_depth + while !self.scope.locals.is_empty() + && self.scope.locals[self.scope.locals.len() - 1].depth > self.scope.scope_depth { pops += 1; - scope.locals.pop(); + + // While removing the local, analyse whether it has been + // accessed while it existed and emit a warning to the + // user otherwise. + if let Some(Local { + node: Some(node), + used, + .. + }) = self.scope.locals.pop() + { + if !used { + self.emit_warning(node, WarningKind::UnusedBinding); + } + } } if pops > 0 { self.chunk.push_op(OpCode::OpCloseScope(pops)); } - while !scope.with_stack.is_empty() - && scope.with_stack[scope.with_stack.len() - 1].depth > scope.scope_depth + while !self.scope.with_stack.is_empty() + && self.scope.with_stack[self.scope.with_stack.len() - 1].depth > self.scope.scope_depth { self.chunk.push_op(OpCode::OpPopWith); - scope.with_stack.pop(); + self.scope.with_stack.pop(); } } /// Declare a local variable known in the scope that is being /// compiled by pushing it to the locals. This is used to /// determine the stack offset of variables. - fn declare_local<S: Into<String>>(&mut self, name: S) { + fn declare_local<S: Into<String>>(&mut self, node: rnix::SyntaxNode, name: S) { // Set up scope poisoning if required. let name = name.into(); match name.as_str() { @@ -786,24 +810,29 @@ impl Compiler { self.scope.locals.push(Local { name: name.into(), + node: Some(node), depth: self.scope.scope_depth, phantom: false, + used: false, }); } fn declare_phantom(&mut self) { self.scope.locals.push(Local { name: "".into(), + node: None, depth: self.scope.scope_depth, phantom: true, + used: true, }); } fn resolve_local(&mut self, name: &str) -> Option<usize> { - let scope = &self.scope; + let scope = &mut self.scope; - for (idx, local) in scope.locals.iter().enumerate().rev() { + for (idx, local) in scope.locals.iter_mut().enumerate().rev() { if !local.phantom && local.name == name { + local.used = true; return Some(idx); } } diff --git a/tvix/eval/src/warnings.rs b/tvix/eval/src/warnings.rs index 558a833662e9..20aa9677466e 100644 --- a/tvix/eval/src/warnings.rs +++ b/tvix/eval/src/warnings.rs @@ -5,6 +5,7 @@ pub enum WarningKind { DeprecatedLiteralURL, UselessInherit, + UnusedBinding, } #[derive(Debug)] |