checker: check that type exists in TypeDecl

vlib/v/checker/checker.v

@@ -155,6 +155,40 @@ fn (mut c Checker) check_file_in_main(file ast.File) bool {
 	return has_main_fn
 }
 
+pub fn (mut c Checker) type_decl(node ast.TypeDecl) {
+	match node {
+		ast.AliasTypeDecl {
+			typ_sym := c.table.get_type_symbol(it.parent_type)
+			if typ_sym.kind == .placeholder {
+				c.error("type `$typ_sym.name` doesn't exist", it.pos)
+			}
+		}
+		ast.FnTypeDecl {
+			typ_sym := c.table.get_type_symbol(it.typ)
+			fn_typ_info := typ_sym.info as table.FnType
+			fn_info := fn_typ_info.func
+			ret_sym := c.table.get_type_symbol(fn_info.return_type)
+			if ret_sym.kind == .placeholder {
+				c.error("type `$ret_sym.name` doesn't exist", it.pos)
+			}
+			for arg in fn_info.args {
+				arg_sym := c.table.get_type_symbol(arg.typ)
+				if arg_sym.kind == .placeholder {
+					c.error("type `$arg_sym.name` doesn't exist", it.pos)
+				}
+			}
+		}
+		ast.SumTypeDecl {
+			for typ in it.sub_types {
+				typ_sym := c.table.get_type_symbol(typ)
+				if typ_sym.kind == .placeholder {
+					c.error("type `$typ_sym.name` doesn't exist", it.pos)
+				}
+			}
+		}
+	}
+}
+
 pub fn (mut c Checker) struct_decl(decl ast.StructDecl) {
 	splitted_full_name := decl.name.split('.')
 	is_builtin := splitted_full_name[0] == 'builtin'
@@ -1088,6 +1122,7 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 					it.pos)
 			}
 		}
+		// ast.Attr {}
 		ast.AssignStmt {
 			c.assign_stmt(mut it)
 		}
@@ -1099,7 +1134,6 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 				c.error('$it.tok.lit statement not within a loop', it.tok.position())
 			}
 		}
-		// ast.Attr {}
 		ast.CompIf {
 			// c.expr(it.cond)
 			c.stmts(it.stmts)
@@ -1170,17 +1204,6 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 			}
 			c.returns = false
 		}
-		ast.ForStmt {
-			c.in_for_count++
-			typ := c.expr(it.cond)
-			if !it.is_inf && typ.idx() != table.bool_type_idx {
-				c.error('non-bool used as for condition', it.pos)
-			}
-			// TODO: update loop var type
-			// how does this work currenly?
-			c.stmts(it.stmts)
-			c.in_for_count--
-		}
 		ast.ForCStmt {
 			c.in_for_count++
 			c.stmt(it.init)
@@ -1230,8 +1253,20 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 			c.stmts(it.stmts)
 			c.in_for_count--
 		}
+		ast.ForStmt {
+			c.in_for_count++
+			typ := c.expr(it.cond)
+			if !it.is_inf && typ.idx() != table.bool_type_idx {
+				c.error('non-bool used as for condition', it.pos)
+			}
+			// TODO: update loop var type
+			// how does this work currenly?
+			c.stmts(it.stmts)
+			c.in_for_count--
+		}
+		// ast.GlobalDecl {}
 		ast.GoStmt {
-			if !is_call_expr(it.call_expr) {
+			if !(it.call_expr is ast.CallExpr) {
 				c.error('expression in `go` must be a function call', it.call_expr.position())
 			}
 			c.expr(it.call_expr)
@@ -1242,7 +1277,6 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 			c.mod = it.name
 			c.is_builtin_mod = it.name == 'builtin'
 		}
-		// ast.GlobalDecl {}
 		ast.Return {
 			c.returns = true
 			c.return_stmt(mut it)
@@ -1250,6 +1284,9 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 		ast.StructDecl {
 			c.struct_decl(it)
 		}
+		ast.TypeDecl {
+			c.type_decl(it)
+		}
 		ast.UnsafeStmt {
 			c.stmts(it.stmts)
 		}
@@ -1260,13 +1297,6 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 	}
 }
 
-fn is_call_expr(expr ast.Expr) bool {
-	return match expr {
-		ast.CallExpr { true }
-		else { false }
-	}
-}
-
 fn (mut c Checker) stmts(stmts []ast.Stmt) {
 	c.expected_type = table.void_type
 	for stmt in stmts {

vlib/v/checker/tests/inout/alias_type_exists.out

@@ -0,0 +1,5 @@
+vlib/v/checker/tests/inout/alias_type_exists.v:1:1: error: type `Bird` doesn't exist
+    1| type Pigeon = Bird
+       ~~~~~~~~~~~
+    2|
+    3| fn main() {

vlib/v/checker/tests/inout/alias_type_exists.vv

@@ -0,0 +1,5 @@
+type Pigeon = Bird
+
+fn main() {
+
+}

vlib/v/checker/tests/inout/fn_type_exists.out

@@ -0,0 +1,12 @@
+vlib/v/checker/tests/inout/fn_type_exists.v:1:1: error: type `Pants` doesn't exist
+    1| type PantsCreator = fn (a Shirt) Pants
+       ~~~~~~~~~~~~~~~~~
+    2|
+    3| type PantsConsumer = fn (p Pants)
+vlib/v/checker/tests/inout/fn_type_exists.v:3:1: error: type `Pants` doesn't exist
+    1| type PantsCreator = fn (a Shirt) Pants
+    2|
+    3| type PantsConsumer = fn (p Pants)
+       ~~~~~~~~~~~~~~~~~~
+    4|
+    5| fn main() {

vlib/v/checker/tests/inout/fn_type_exists.vv

@@ -0,0 +1,7 @@
+type PantsCreator = fn (a Shirt) Pants
+
+type PantsConsumer = fn (p Pants)
+
+fn main() {
+
+}

vlib/v/checker/tests/inout/sum_type_exists.out

@@ -0,0 +1,5 @@
+vlib/v/checker/tests/inout/sum_type_exists.v:1:1: error: type `Nope` doesn't exist
+    1| type Miscellaneous = Nope | Inexistant | int
+       ~~~~~~~~~~~~~~~~~~
+    2|
+    3| fn main() {

vlib/v/checker/tests/inout/sum_type_exists.vv

@@ -0,0 +1,5 @@
+type Miscellaneous = Nope | Inexistant | int
+
+fn main() {
+
+}