fix: check if number of types in declaration exceeds number of variables

Fixes #868.
teal-language · Dec 31, 2024 · 43def7f · 43def7f
1 parent 44ced6a
commit 43def7f
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Showing 3 changed files with 34 additions and 4 deletions.
diff --git a/spec/lang/declaration/local_spec.lua b/spec/lang/declaration/local_spec.lua
@@ -385,4 +385,18 @@ describe("local", function()
       { y = 9, msg = "_bar1: got number, expected Bar" },
       { y = 10, msg = "_bar2: Foo is not a Bar" },
    }))
+
+   it("catches excessive types in declaration (regression test for #868)", util.check_type_error([[
+      local function f(): string, string
+         return "hello", "world"
+      end
+
+      local x, y: integer, string, string = 1, ""
+
+      local z, w = 0, f()
+
+      z, w = 0, f()
+   ]], {
+      { y = 5, x = 36, msg = "number of types exceeds number of variables" },
+   }))
 end)
diff --git a/tl.lua b/tl.lua
@@ -10908,7 +10908,7 @@ a.types[i], b.types[i]), }
       end
    end
 
-   local function set_expected_types_to_decltuple(_, node, children)
+   local function set_expected_types_to_decltuple(self, node, children)
       local decltuple = node.kind == "assignment" and children[1] or node.decltuple
       assert(decltuple.typename == "tuple")
       local decls = decltuple.tuple
@@ -10919,7 +10919,7 @@ a.types[i], b.types[i]), }
             local typ
             typ = decls[i]
             if typ then
-               if i == nexps and ndecl > nexps then
+               if node.kind == "assignment" and i == nexps and ndecl > nexps then
                   typ = a_type(node, "tuple", { tuple = {} })
                   for a = i, ndecl do
                      table.insert(typ.tuple, decls[a])
@@ -10930,6 +10930,14 @@ a.types[i], b.types[i]), }
             end
          end
       end
+
+      if node.decltuple then
+         local ndecltuple = #node.decltuple.tuple
+         local nvars = #node.vars
+         if ndecltuple > nvars then
+            self.errs:add(node.decltuple.tuple[nvars + 1], "number of types exceeds number of variables")
+         end
+      end
    end
 
    local function is_positive_int(n)

diff --git a/tl.tl b/tl.tl
@@ -10908,7 +10908,7 @@ do
       end
    end
 
-   local function set_expected_types_to_decltuple(_: TypeChecker, node: Node, children: {Type})
+   local function set_expected_types_to_decltuple(self: TypeChecker, node: Node, children: {Type})
       local decltuple = node.kind == "assignment" and children[1] or node.decltuple
       assert(decltuple is TupleType)
       local decls = decltuple.tuple
@@ -10919,7 +10919,7 @@ do
             local typ: Type
             typ = decls[i]
             if typ then
-               if i == nexps and ndecl > nexps then
+               if node.kind == "assignment" and i == nexps and ndecl > nexps then
                   typ = a_tuple(node, {})
                   for a = i, ndecl do
                      table.insert(typ.tuple, decls[a])
@@ -10930,6 +10930,14 @@ do
             end
          end
       end
+
+      if node.decltuple then
+         local ndecltuple = #node.decltuple.tuple
+         local nvars = #node.vars
+         if ndecltuple > nvars then
+            self.errs:add(node.decltuple.tuple[nvars + 1], "number of types exceeds number of variables")
+         end
+      end
    end
 
    local function is_positive_int(n: number): boolean