Merge branch 'unusued-variables' into fix-constant-bug

3 files changed, 148 insertions, 68 deletions

diff --git a/src/compiler.rs b/src/compiler.rs
index c70640d..7b9fd9a 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!("Usage of undefined 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()
     }
@@ -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));
@@ -931,7 +978,8 @@ impl Compiler {
             }
         }
 
-        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 {
@@ -1208,6 +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 {
@@ -1382,23 +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);
         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);
@@ -1416,6 +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 42a74a0..40bae2b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -871,7 +871,7 @@ 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]
@@ -889,10 +889,25 @@ c := 5
 f :: fn {
     c <=> 5
 }
+a
         ";
         assert_errs!(run_string(prog, true, Vec::new()), [ErrorKind::InvalidProgram, ErrorKind::RuntimeTypeError(_, _)]);
     }
 
+    #[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 ),+ $( , )? ) => {
@@ -1066,7 +1081,8 @@ 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()
@@ -1088,6 +1104,7 @@ a() <=> 4
         blob_infer: "
 blob A { }
 a : A = A()
+a
 ",
     );
 
@@ -1095,8 +1112,8 @@ 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");
@@ -1201,6 +1218,7 @@ a <=> 1
 b := 2
 {
     a <=> 1
+    b <=> 2
 }",
     );
 
@@ -1211,6 +1229,7 @@ a := 0
 b := 99999
 a += 1
 a <=> 1
+b <=> 99999
 ",
 
         simple_sub: "
@@ -1218,6 +1237,7 @@ a := 0
 b := 99999
 a -= 1
 a <=> -1
+b <=> 99999
 ",
 
         strange: "
@@ -1237,6 +1257,7 @@ a <=> -1
         declaration_order,
         blob_simple: "
 a := A()
+a
 
 blob A {
     a: int
@@ -1249,6 +1270,11 @@ b := B()
 c := C()
 b2 := B()
 
+a
+b
+c
+b2
+
 blob A {
     c: C
 }
@@ -1260,6 +1286,7 @@ blob B { }
 blob A { }
 
 a : A = A()
+a
 ",
 
 
@@ -1322,4 +1349,5 @@ q <=> 3
 ",
 
     );
+
 }
diff --git a/src/vm.rs b/src/vm.rs
index 5e7810d..8d8ec23 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -838,15 +838,18 @@ mod tests {
         test_string!(uncallable_type, "
                  f := fn i: int {
                      i()
-                 }",
+                 }
+                 f",
                  [ErrorKind::InvalidProgram]);
 
         test_string!(wrong_params, "
-                 f : fn -> int = fn a: int -> int {}",
+                 f : fn -> int = fn a: int -> int {}
+                 f",
                  [ErrorKind::TypeError(_, _), ErrorKind::TypeError(_, _)]);
 
         test_string!(wrong_ret, "
-                 f : fn -> int = fn {}",
+                 f : fn -> int = fn {}
+                 f",
                  [ErrorKind::TypeError(_, _)]);
     }
 }