1 files changed, 75 insertions, 10 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 967f8c4..e8b6c54 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::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 ),+ $( , )? ) => {
@@ -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
 ",
 
     );
+
 }