ast: improve support for type aliases, in TypeSymbol.xyz_info methods

vlib/v/ast/types.v

@@ -564,76 +564,135 @@ pub fn (t TypeSymbol) str() string {
 	return t.name
 }
 
+[noreturn]
+fn (t &TypeSymbol) no_info_panic(fname string) {
+	panic('$fname: no info for type: $t.name')
+}
+
 [inline]
 pub fn (t &TypeSymbol) enum_info() Enum {
-	match mut t.info {
-		Enum { return t.info }
-		else { panic('TypeSymbol.enum_info(): no enum info for type: $t.name') }
+	if t.info is Enum {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is Enum {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) mr_info() MultiReturn {
-	match mut t.info {
-		MultiReturn { return t.info }
-		else { panic('TypeSymbol.mr_info(): no multi return info for type: $t.name') }
+	if t.info is MultiReturn {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is MultiReturn {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) array_info() Array {
-	match mut t.info {
-		Array { return t.info }
-		else { panic('TypeSymbol.array_info(): no array info for type: $t.name') }
+	if t.info is Array {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is Array {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) array_fixed_info() ArrayFixed {
-	match mut t.info {
-		ArrayFixed { return t.info }
-		else { panic('TypeSymbol.array_fixed(): no array fixed info for type: $t.name') }
+	if t.info is ArrayFixed {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is ArrayFixed {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) chan_info() Chan {
-	match mut t.info {
-		Chan { return t.info }
-		else { panic('TypeSymbol.chan_info(): no chan info for type: $t.name') }
+	if t.info is Chan {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is Chan {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) thread_info() Thread {
-	match mut t.info {
-		Thread { return t.info }
-		else { panic('TypeSymbol.thread_info(): no thread info for type: $t.name') }
+	if t.info is Thread {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is Thread {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) map_info() Map {
-	match mut t.info {
-		Map { return t.info }
-		else { panic('TypeSymbol.map_info(): no map info for type: $t.name') }
+	if t.info is Map {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is Map {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) struct_info() Struct {
-	match mut t.info {
-		Struct { return t.info }
-		else { panic('TypeSymbol.struct_info(): no struct info for type: $t.name') }
+	if t.info is Struct {
+		return t.info
 	}
+	if t.info is Alias {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is Struct {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 [inline]
 pub fn (t &TypeSymbol) sumtype_info() SumType {
-	match mut t.info {
-		SumType { return t.info }
-		else { panic('TypeSymbol.sumtype_info(): no sumtype info for type: $t.name') }
+	if t.info is SumType {
+		return t.info
 	}
+	if t.info is SumType {
+		fsym := global_table.final_sym(t.info.parent_type)
+		if fsym.info is SumType {
+			return fsym.info
+		}
+	}
+	t.no_info_panic(@METHOD)
 }
 
 pub fn (t &TypeSymbol) is_heap() bool {