cgen/parser: fix unions

vlib/strconv/atof_test.v

@@ -74,5 +74,5 @@ fn test_atof() {
 	// DOUBLE_MINUS_ZERO
 	f1=-0.0
 	assert *ptr == u64(0x8000000000000000)
-	//println("DONE!")
+	println("DONE!")
 }

vlib/v/ast/ast.v

@@ -150,6 +150,7 @@ pub:
 	pub_pos       int // pub:
 	pub_mut_pos   int // pub mut:
 	is_c          bool
+	is_union bool
 }
 
 pub struct InterfaceDecl {

vlib/v/gen/cgen.v

@@ -86,7 +86,7 @@ pub fn cgen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 		indent: -1
 	}
 	g.init()
-	//
+	// 
 	mut autofree_used := false
 	for file in files {
 		g.file = file
@@ -115,7 +115,7 @@ pub fn cgen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 	if g.is_test {
 		g.write_tests_main()
 	}
-	//
+	// 
 	g.finish()
 	return g.hashes() + g.includes.str() + g.typedefs.str() + g.typedefs2.str() + g.definitions.str() +
 		g.gowrappers.str() + g.stringliterals.str() + g.out.str()
@@ -141,7 +141,7 @@ pub fn (g mut Gen) init() {
 	g.write_sorted_types()
 	g.write_multi_return_types()
 	g.definitions.writeln('// end of definitions #endif')
-	//
+	// 
 	g.stringliterals.writeln('')
 	g.stringliterals.writeln('// >> string literal consts')
 	g.stringliterals.writeln('void vinit_string_literals(){')
@@ -205,7 +205,7 @@ pub fn (g mut Gen) typ(t table.Type) string {
 	return styp
 }
 
-//
+// 
 pub fn (g mut Gen) write_typedef_types() {
 	for typ in g.table.types {
 		match typ.kind {
@@ -460,7 +460,12 @@ fn (g mut Gen) stmt(node ast.Stmt) {
 			// g.writeln('\t$field_type_sym.name $field.name;')
 			// }
 			// g.writeln('} $name;')
-			if !it.is_c {
+			if it.is_c {
+				return
+			}
+			if it.is_union {
+				g.typedefs.writeln('typedef union $name $name;')
+			} else {
 				g.typedefs.writeln('typedef struct $name $name;')
 			}
 		}
@@ -817,7 +822,7 @@ fn (g mut Gen) gen_fn_decl(it ast.FnDecl) {
 		}
 	}
 */
-	//
+	// 
 	g.fn_args(it.args, it.is_variadic)
 	if it.no_body {
 		// Just a function header.
@@ -1452,7 +1457,7 @@ fn (g mut Gen) match_expr(node ast.MatchExpr) {
 					// sum_type_str
 				} else if type_sym.kind == .string {
 					g.write('string_eq(')
-					//
+					// 
 					g.expr(node.cond)
 					g.write(', ')
 					// g.write('string_eq($tmp, ')
@@ -2121,7 +2126,11 @@ fn (g mut Gen) write_types(types []table.TypeSymbol) {
 			table.Struct {
 				info := typ.info as table.Struct
 				// g.definitions.writeln('typedef struct {')
-				g.definitions.writeln('struct $name {')
+				if info.is_union {
+					g.definitions.writeln('union $name {')
+				} else {
+					g.definitions.writeln('struct $name {')
+				}
 				if info.fields.len > 0 {
 					for field in info.fields {
 						type_name := g.typ(field.typ)
@@ -2132,7 +2141,7 @@ fn (g mut Gen) write_types(types []table.TypeSymbol) {
 					g.definitions.writeln('EMPTY_STRUCT_DECLARATION;')
 				}
 				// g.definitions.writeln('} $name;\n')
-				//
+				// 
 				g.definitions.writeln('};\n')
 			}
 			table.Alias {

vlib/v/parser/parser.v

@@ -661,8 +661,8 @@ pub fn (p mut Parser) name_expr() ast.Expr {
 			x := p.call_expr(is_c, mod)			// TODO `node,typ :=` should work
 			node = x
 		}
-	} else if p.peek_tok.kind == .lcbr && !p.inside_match_case && (is_c || p.tok.lit[0].is_capital() || 
+	} else if p.peek_tok.kind == .lcbr && !p.inside_match_case && (is_c || p.tok.lit[0].is_capital() ||
-		(p.builtin_mod && p.tok.lit in table.builtin_type_names)) && (p.tok.lit.len in [1, 2, 3] || 
+		(p.builtin_mod && p.tok.lit in table.builtin_type_names)) && (p.tok.lit.len in [1, 2, 3] ||
 		!p.tok.lit[p.tok.lit.len - 1].is_capital() || p.table.known_type(p.tok.lit)) {
 		// short_syntax: false
 		return p.struct_init(false)
@@ -1447,6 +1447,7 @@ fn (p mut Parser) struct_decl() ast.StructDecl {
 	if is_pub {
 		p.next()
 	}
+	is_union := p.tok.kind == .key_union
 	if p.tok.kind == .key_struct {
 		p.check(.key_struct)
 	} else {
@@ -1535,6 +1536,7 @@ fn (p mut Parser) struct_decl() ast.StructDecl {
 		info: table.Struct{
 			fields: fields
 			is_typedef: is_typedef
+			is_union: is_union
 		}
 	}
 	mut ret := 0
@@ -1558,6 +1560,7 @@ fn (p mut Parser) struct_decl() ast.StructDecl {
 		pub_pos: pub_pos
 		pub_mut_pos: pub_mut_pos
 		is_c: is_c
+		is_union: is_union
 	}
 }
 

vlib/v/table/atypes.v

@@ -540,6 +540,7 @@ pub struct Struct {
 pub mut:
 	fields []Field
 	is_typedef bool // C. [typedef]
+	is_union bool
 }
 
 pub struct Enum {