Merge pull request #67 from FredTheDino/unusued-variables

unusued variables

3 files changed, 218 insertions, 89 deletions

diff --git a/src/compiler.rs b/src/compiler.rs
index 94ae2aa..cd4ffda 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -113,12 +113,13 @@ nextable_enum!(Prec {
     Factor,
 });
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 struct Variable {
     name: String,
     typ: Type,
     scope: usize,
     slot: usize,
+    line: usize,
 
     outer_slot: usize,
     outer_upvalue: bool,
@@ -127,6 +128,28 @@ struct Variable {
     upvalue: bool,
     captured: bool,
     mutable: bool,
+    read: bool,
+}
+
+impl Variable {
+    fn new(name: &str, mutable: bool, typ: Type) -> Self {
+        Self {
+            name: String::from(name),
+            typ,
+            scope: 0,
+            slot: 0,
+            line: 0,
+
+            outer_slot: 0,
+            outer_upvalue: false,
+
+            active: false,
+            upvalue: false,
+            captured: false,
+            mutable,
+            read: false,
+        }
+    }
 }
 
 enum LoopOp {
@@ -242,10 +265,27 @@ macro_rules! push_frame {
             $compiler.frames.push(Frame::new());
 
             // Return value stored as a variable
-            $compiler.define_variable("", Type::Unknown, &mut $block).unwrap();
+            let var = Variable::new("", true, Type::Unknown);
+            $compiler.define(var).unwrap();
+
             $code
 
-            $compiler.frames.pop().unwrap();
+            let frame = $compiler.frames.pop().unwrap();
+            // 0-th slot is the function itself.
+            for var in frame.stack.iter().skip(1) {
+                if !(var.read || var.upvalue) {
+                    let e = ErrorKind::SyntaxError(
+                        var.line,
+                        Token::Identifier(var.name.clone()
+                    ));
+                    $compiler.error_on_line(
+                        e,
+                        var.line,
+                        Some(format!("Unused value '{}'.", var.name))
+                    );
+                }
+                $compiler.panic = false;
+            }
             // The 0th slot is the return value, which is passed out
             // from functions, and should not be popped.
             0
@@ -262,13 +302,30 @@ macro_rules! push_scope {
 
         $compiler.frame_mut().scope -= 1;
 
-        for var in $compiler.frame().stack[ss..$compiler.stack().len()].iter().rev() {
+        let mut errors = Vec::new();
+        for var in $compiler.frame().stack.iter().skip(ss).rev() {
+            if !(var.read || var.upvalue) {
+                let e = ErrorKind::SyntaxError(
+                    var.line,
+                    Token::Identifier(var.name.clone()
+                ));
+                errors.push((
+                    e,
+                    var.line,
+                    format!("Usage of undefined value: '{}'.", var.name),)
+                );
+            }
             if var.captured {
                 add_op($compiler, $block, Op::PopUpvalue);
             } else {
                 add_op($compiler, $block, Op::Pop);
             }
         }
+
+        for (e, l, m) in errors.iter() {
+            $compiler.error_on_line(e.clone(), *l, Some(m.clone()));
+            $compiler.panic = false;
+        }
         $compiler.stack_mut().truncate(ss);
     };
 }
@@ -337,6 +394,26 @@ impl Compiler {
         &mut self.frames[last]
     }
 
+    /// Marks a variable as read. Also marks upvalues.
+    fn mark_read(&mut self, frame_id: usize, var: &Variable) {
+        // Early out
+        if var.read {
+            return;
+        }
+
+
+        if if let Some(up) = self.frames[frame_id].upvalues.get(var.slot) {
+            up.name == var.name
+        } else { false } {
+            let mut inner_var = self.frames[frame_id].upvalues[var.slot].clone();
+            inner_var.slot = inner_var.outer_slot;
+            self.mark_read(frame_id - 1, &inner_var);
+            self.frames[frame_id].upvalues[var.slot].read = true;
+        } else {
+            self.frames[frame_id].stack[var.slot].read = true;
+        }
+    }
+
     fn stack(&self) -> &[Variable] {
         &self.frame().stack.as_ref()
     }
@@ -719,10 +796,10 @@ impl Compiler {
 
         let mut args = Vec::new();
         let mut return_type = Type::Void;
-        let mut function_block = Block::new(&name, &self.current_file, self.line());
+        let mut function_block = Block::new(&name, &self.current_file);
 
         let block_id = self.blocks.len();
-        let temp_block = Block::new(&name, &self.current_file, self.line());
+        let temp_block = Block::new(&name, &self.current_file);
         self.blocks.push(Rc::new(RefCell::new(temp_block)));
 
         let _ret = push_frame!(self, function_block, {
@@ -733,7 +810,8 @@ impl Compiler {
                         expect!(self, Token::Colon, "Expected ':' after parameter name.");
                         if let Ok(typ) = self.parse_type() {
                             args.push(typ.clone());
-                            if let Ok(slot) = self.define_variable(&name, typ, &mut function_block) {
+                            let var = Variable::new(&name, true, typ);
+                            if let Ok(slot) = self.define(var) {
                                 self.stack_mut()[slot].active = true;
                             }
                         } else {
@@ -814,6 +892,7 @@ impl Compiler {
 
         // Variables
         if let Some(var) = self.find_variable(&name) {
+            self.mark_read(self.frames.len() - 1, &var);
             if var.upvalue {
                 add_op(self, block, Op::ReadUpvalue(var.slot));
             } else {
@@ -846,58 +925,26 @@ impl Compiler {
         parse_branch!(self, block, self.call(block));
     }
 
-    fn define_variable(&mut self, name: &str, typ: Type, _block: &mut Block) -> Result<usize, ()> {
-        if let Some(var) = self.find_variable(&name) {
-            if var.scope == self.frame().scope {
-                error!(self, format!("Multiple definitions of {} in this block.", name));
-                return Err(());
-            }
-        }
-
-        let slot = self.stack().len();
-        let scope = self.frame().scope;
-        self.stack_mut().push(Variable {
-            name: String::from(name),
-            captured: false,
-            outer_upvalue: false,
-            outer_slot: 0,
-            slot,
-            typ,
-            scope,
-            active: false,
-            upvalue: false,
-            mutable: true,
-        });
-        Ok(slot)
-    }
-
-    fn define_constant(&mut self, name: &str, typ: Type, _block: &mut Block) -> Result<usize, ()> {
-        if let Some(var) = self.find_variable(&name) {
+    fn define(&mut self, mut var: Variable) -> Result<usize, ()> {
+        if let Some(var) = self.find_variable(&var.name) {
             if var.scope == self.frame().scope {
-                error!(self, format!("Multiple definitions of {} in this block.", name));
+                error!(self, format!("Multiple definitions of '{}' in this block.",
+                                     var.name));
                 return Err(());
             }
         }
 
         let slot = self.stack().len();
-        let scope = self.frame().scope;
-        self.stack_mut().push(Variable {
-            name: String::from(name),
-            captured: false,
-            outer_upvalue: false,
-            outer_slot: 0,
-            slot,
-            typ,
-            scope,
-            active: false,
-            upvalue: false,
-            mutable: false,
-        });
+        var.slot = slot;
+        var.scope = self.frame().scope;
+        var.line = self.line();
+        self.stack_mut().push(var);
         Ok(slot)
     }
 
     fn definition_statement(&mut self, name: &str, typ: Type, block: &mut Block) {
-        let slot = self.define_variable(name, typ.clone(), block);
+        let var = Variable::new(name, true, typ.clone());
+        let slot = self.define(var);
         self.expression(block);
         let constant = self.add_constant(Value::Ty(typ));
         add_op(self, block, Op::Define(constant));
@@ -914,18 +961,25 @@ impl Compiler {
                 // Remove the function, since it's a constant and we already
                 // added it.
                 block.ops.pop().unwrap();
-                if let Entry::Occupied(entry) = self.unknown.entry(String::from(name)) {
+                let slot = if let Entry::Occupied(entry) = self.unknown.entry(String::from(name)) {
                     let (_, (slot, _)) = entry.remove_entry();
                     self.constants[slot] = self.constants.pop().unwrap();
-                    add_op(self, block, Op::Link(slot));
+                    slot
                 } else {
-                    add_op(self, block, Op::Link(self.constants.len() - 1));
+                    self.constants.len() - 1
+                };
+                add_op(self, block, Op::Link(slot));
+                if let Value::Function(_, block) = &self.constants[slot] {
+                    block.borrow_mut().mark_constant();
+                } else {
+                    unreachable!();
                 }
                 return;
             }
         }
 
-        let slot = self.define_constant(name, typ.clone(), block);
+        let var = Variable::new(name, false, typ);
+        let slot = self.define(var);
         self.expression(block);
 
         if let Ok(slot) = slot {
@@ -1202,6 +1256,7 @@ impl Compiler {
             _ => unreachable!(),
         };
         if let Some(var) = self.find_variable(&name) {
+            self.mark_read(self.frames.len() - 1, &var);
             if var.upvalue {
                 add_op(self, block, Op::ReadUpvalue(var.slot));
             } else {
@@ -1376,23 +1431,14 @@ impl Compiler {
             .enumerate()
             .map(|(i, (s, f))| (s, (i, f)))
             .collect();
-        self.stack_mut().push(Variable {
-            name: String::from("/main/"),
-            typ: Type::Void,
-            outer_upvalue: false,
-            outer_slot: 0,
-            slot: 0,
-            scope: 0,
-            active: false,
-            captured: false,
-            upvalue: false,
-            mutable: true,
-        });
+        let main = Variable::new("/main/", false, Type::Void);
+        let _ = self.define(main);
 
-        let mut block = Block::new(name, file, 0);
+        let mut block = Block::new(name, file);
         while self.peek() != Token::EOF {
             self.statement(&mut block);
-            expect!(self, Token::Newline | Token::EOF, "Expect newline or EOF after expression.");
+            expect!(self, Token::Newline | Token::EOF,
+                    "Expect newline or EOF after expression.");
         }
         add_op(self, &mut block, Op::Constant(self.nil_value()));
         add_op(self, &mut block, Op::Return);
@@ -1410,6 +1456,15 @@ impl Compiler {
             }
         }
 
+        for var in self.frames.pop().unwrap().stack.iter().skip(1) {
+            if !(var.read || var.upvalue) {
+                let e = ErrorKind::SyntaxError(var.line, Token::Identifier(var.name.clone()));
+                let m = format!("Unused value '{}'.", var.name);
+                self.error_on_line(e, var.line, Some(m));
+            }
+            self.panic = false;
+        }
+
         self.blocks.insert(0, Rc::new(RefCell::new(block)));
 
         if self.errors.is_empty() {
diff --git a/src/lib.rs b/src/lib.rs
index 7f79a66..91938f1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -151,7 +151,7 @@ impl From<&Type> for Value {
             Type::String => Value::String(Rc::new("".to_string())),
             Type::Function(_, _) => Value::Function(
                 Vec::new(),
-                Rc::new(RefCell::new(Block::empty_with_type(ty)))),
+                Rc::new(RefCell::new(Block::stubbed_block(ty)))),
         }
     }
 }
@@ -626,35 +626,58 @@ mod op {
 }
 
 #[derive(Debug)]
+enum BlockLinkState {
+    Linked,
+    Unlinked,
+    Nothing,
+}
+
+#[derive(Debug)]
 pub struct Block {
     pub ty: Type,
     upvalues: Vec<(usize, bool, Type)>,
+    linking: BlockLinkState,
 
     pub name: String,
     pub file: PathBuf,
     ops: Vec<Op>,
     last_line_offset: usize,
     line_offsets: HashMap<usize, usize>,
-    line: usize,
 }
 
 impl Block {
-    fn new(name: &str, file: &Path, line: usize) -> Self {
+    fn new(name: &str, file: &Path) -> Self {
         Self {
             ty: Type::Void,
             upvalues: Vec::new(),
+            linking: BlockLinkState::Nothing,
+
             name: String::from(name),
             file: file.to_owned(),
             ops: Vec::new(),
             last_line_offset: 0,
             line_offsets: HashMap::new(),
-            line,
         }
     }
 
+    fn mark_constant(&mut self) {
+        if self.upvalues.is_empty() {
+            return;
+        }
+        self.linking = BlockLinkState::Unlinked;
+    }
+
+    fn link(&mut self) {
+        self.linking = BlockLinkState::Linked;
+    }
+
+    fn needs_linking(&self) -> bool {
+        matches!(self.linking, BlockLinkState::Unlinked)
+    }
+
     // Used to create empty functions.
-    fn empty_with_type(ty: &Type) -> Self {
-        let mut block = Block::new("/empty/", Path::new(""), 0);
+    fn stubbed_block(ty: &Type) -> Self {
+        let mut block = Block::new("/empty/", Path::new(""));
         block.ty = ty.clone();
         block
     }
@@ -865,7 +888,7 @@ mod tests {
 
     #[test]
     fn assign_to_constant_upvalue() {
-        assert_errs!(run_string("a :: 2\nq :: fn { a = 2 }\n", true, Vec::new()), [ErrorKind::SyntaxError(_, _)]);
+        assert_errs!(run_string("a :: 2\nq :: fn { a = 2 }\nq()\na", true, Vec::new()), [ErrorKind::SyntaxError(_, _)]);
     }
 
     #[test]
@@ -873,6 +896,35 @@ mod tests {
         assert_errs!(run_string("a :: B()\n", true, Vec::new()), [ErrorKind::SyntaxError(_, _)]);
     }
 
+    #[test]
+    fn call_before_link() {
+        let prog = "
+a := 1
+f()
+c := 5
+
+f :: fn {
+    c <=> 5
+}
+a
+        ";
+        assert_errs!(run_string(prog, true, Vec::new()), [ErrorKind::InvalidProgram, ErrorKind::TypeError(_, _)]);
+    }
+
+    #[test]
+    fn unused_variable() {
+        assert_errs!(run_string("a := 1", true, Vec::new()), [ErrorKind::SyntaxError(1, _)]);
+    }
+
+    #[test]
+    fn unused_upvalue() {
+        assert_errs!(run_string("a := 1\nf :: fn { a = 2 }\nf()", true, Vec::new()), [ErrorKind::SyntaxError(1, _)]);
+    }
+
+    #[test]
+    fn unused_function() {
+        assert_errs!(run_string("a := 1\nf := fn { a }\n", true, Vec::new()), [ErrorKind::SyntaxError(2, _)]);
+    }
 
     macro_rules! test_multiple {
         ($mod:ident, $( $fn:ident : $prog:literal ),+ $( , )? ) => {
@@ -1046,7 +1098,8 @@ a() <=> 4
         blob,
         simple: "blob A {}",
         instantiate: "blob A {}
-                      a := A()",
+                      a := A()
+                      a",
         field: "blob A { a: int }",
         field_assign: "blob A { a: int }
                        a := A()
@@ -1068,6 +1121,7 @@ a() <=> 4
         blob_infer: "
 blob A { }
 a : A = A()
+a
 ",
     );
 
@@ -1075,8 +1129,8 @@ a : A = A()
         add: "(1, 2, 3, 4) + (4, 3, 2, 1) <=> (5, 5, 5, 5)",
         sub: "(1, -2, 3, -4) - (4, 3, -2, -1) <=> (-3, 1, 1, -5)",
         mul: "(0, 1, 2) * (2, 3, 4) <=> (0, 3, 8)",
-        types: "a: (int, float, int) = (1, 1., 1)",
-        more_types: "a: (str, bool, int) = (\"abc\", true, 1)",
+        types: "a: (int, float, int) = (1, 1., 1)\na",
+        more_types: "a: (str, bool, int) = (\"abc\", true, 1)\na",
     );
 
     test_file!(scoping, "progs/tests/scoping.sy");
@@ -1181,6 +1235,7 @@ a <=> 1
 b := 2
 {
     a <=> 1
+    b <=> 2
 }",
     );
 
@@ -1191,6 +1246,7 @@ a := 0
 b := 99999
 a += 1
 a <=> 1
+b <=> 99999
 ",
 
         simple_sub: "
@@ -1198,6 +1254,7 @@ a := 0
 b := 99999
 a -= 1
 a <=> -1
+b <=> 99999
 ",
 
         strange: "
@@ -1217,6 +1274,7 @@ a <=> -1
         declaration_order,
         blob_simple: "
 a := A()
+a
 
 blob A {
     a: int
@@ -1229,6 +1287,11 @@ b := B()
 c := C()
 b2 := B()
 
+a
+b
+c
+b2
+
 blob A {
     c: C
 }
@@ -1240,6 +1303,7 @@ blob B { }
 blob A { }
 
 a : A = A()
+a
 ",
 
 
@@ -1302,4 +1366,5 @@ q <=> 3
 ",
 
     );
+
 }
diff --git a/src/vm.rs b/src/vm.rs
index 020e90c..f5e5c58 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -554,6 +554,13 @@ impl VM {
                     Value::Function(_, block) => {
                         self.push(Value::Function(Vec::new(), block.clone()));
 
+                        if block.borrow().needs_linking() {
+                            error!(self,
+                                ErrorKind::InvalidProgram,
+                                format!("Calling function '{}' before all captured variables are declared.",
+                                    block.borrow().name));
+                        }
+
                         let mut types = Vec::new();
                         for (slot, is_up, ty) in block.borrow().upvalues.iter() {
                             if *is_up {
@@ -669,10 +676,10 @@ impl VM {
             }
 
             Op::Link(slot) => {
-                println!("{:?}", self.constants);
-                println!("{:?} - {}", self.constant(slot), slot);
                 match self.constant(slot).clone() {
-                    Value::Function(_, _) => {}
+                    Value::Function(_, block) => {
+                        block.borrow_mut().link();
+                    }
                     value => {
                         error!(self,
                             ErrorKind::TypeError(op, vec![Type::from(&value)]),
@@ -728,8 +735,9 @@ impl VM {
                         self.push(res);
                     }
                     _ => {
-                        error!(self, ErrorKind::ValueError(op, vec![self.stack[new_base].clone()]),
-                               "Tried to call non-function.");
+                        error!(self,
+                            ErrorKind::InvalidProgram,
+                            format!("Tried to call non-function {:?}", self.stack[new_base]));
                     }
                 }
             }
@@ -768,7 +776,7 @@ impl VM {
         });
 
         if self.print_blocks {
-            println!("\n    [[{}]]\n", "TYPECHECK".purple());
+            println!("\n    [[{} - {}]]\n", "TYPECHECKING".purple(), self.frame().block.borrow().name);
             self.frame().block.borrow().debug_print();
         }
 
@@ -821,23 +829,24 @@ impl VM {
 mod tests {
     mod typing {
         use crate::error::ErrorKind;
-        use crate::{test_string, Op, Type};
+        use crate::{test_string, Type};
 
         test_string!(uncallable_type, "
                  f := fn i: int {
                      i()
-                 }",
-                 [ErrorKind::ValueError(Op::Call(0), _)]);
+                 }
+                 f",
+                 [ErrorKind::InvalidProgram]);
 
-        test_string!(invalid_assign, "a := 1\na = 0.1\n",
+        test_string!(invalid_assign, "a := 1\na = 0.1\na",
                  [ErrorKind::TypeMismatch(Type::Int, Type::Float)]);
 
         test_string!(wrong_params, "
-                 f : fn -> int = fn a: int -> int {}",
+                 f : fn -> int = fn a: int -> int {}\nf",
                  [ErrorKind::TypeMismatch(_, _), ErrorKind::TypeMismatch(Type::Void, Type::Int)]);
 
         test_string!(wrong_ret, "
-                 f : fn -> int = fn {}",
+                 f : fn -> int = fn {}\nf",
                  [ErrorKind::TypeMismatch(_, _)]);
     }
 }