compile: fix kwonlyargs and raise SyntaxError on duplicated keywords

Author: ncw

compile/compile.go

@@ -528,8 +528,8 @@ func (c *compiler) compileFunc(compilerScope compilerScopeType, Ast ast.Ast, Arg
 	c.Exprs(Args.Defaults)
 
 	// KwDefaults
-	if len(Args.Kwonlyargs) != len(Args.KwDefaults) {
-		panic("differing number of Kwonlyargs to KwDefaults")
+	if len(Args.KwDefaults) > len(Args.Kwonlyargs) {
+		panic("compile: more KwDefaults than Kwonlyargs")
 	}
 	for i := range Args.KwDefaults {
 		c.LoadConst(py.String(Args.Kwonlyargs[i].Arg))
@@ -1322,11 +1322,16 @@ func (c *compiler) callHelper(n int, Args []ast.Expr, Keywords []*ast.Keyword, S
 		c.Expr(Args[i])
 	}
 	kwargs := len(Keywords)
+	duplicateDetector := make(map[ast.Identifier]struct{}, len(Keywords))
 	for i := range Keywords {
 		kw := Keywords[i]
+		duplicateDetector[kw.Arg] = struct{}{}
 		c.LoadConst(py.String(kw.Arg))
 		c.Expr(kw.Value)
 	}
+	if len(duplicateDetector) != len(Keywords) {
+		panic(py.ExceptionNewf(py.SyntaxError, "keyword argument repeated"))
+	}
 	op := vm.CALL_FUNCTION
 	if Starargs != nil {
 		c.Expr(Starargs)

compile/compile_data_test.go

@@ -2254,6 +2254,7 @@ var compileTestData = []struct {
 		Firstlineno:    1,
 		Lnotab:         "",
 	}, nil, ""},
+	{"f(a=1,a=2)", "eval", nil, py.SyntaxError, "keyword argument repeated"},
 	{"return", "exec", nil, py.SyntaxError, "'return' outside function"},
 	{"def fn(): pass", "exec", &py.Code{
 		Argcount:       0,
@@ -2552,6 +2553,39 @@ var compileTestData = []struct {
 		Firstlineno: 1,
 		Lnotab:      "",
 	}, nil, ""},
+	{"def fn(x,*,a,b): x+a+b", "exec", &py.Code{
+		Argcount:       0,
+		Kwonlyargcount: 0,
+		Nlocals:        0,
+		Stacksize:      2,
+		Flags:          64,
+		Code:           "\x64\x00\x00\x64\x01\x00\x84\x00\x00\x5a\x00\x00\x64\x02\x00\x53",
+		Consts: []py.Object{&py.Code{
+			Argcount:       1,
+			Kwonlyargcount: 2,
+			Nlocals:        3,
+			Stacksize:      2,
+			Flags:          67,
+			Code:           "\x7c\x00\x00\x7c\x01\x00\x17\x7c\x02\x00\x17\x01\x64\x00\x00\x53",
+			Consts:         []py.Object{py.None},
+			Names:          []string{},
+			Varnames:       []string{"x", "a", "b"},
+			Freevars:       []string{},
+			Cellvars:       []string{},
+			Filename:       "<string>",
+			Name:           "fn",
+			Firstlineno:    1,
+			Lnotab:         "",
+		}, py.String("fn"), py.None},
+		Names:       []string{"fn"},
+		Varnames:    []string{},
+		Freevars:    []string{},
+		Cellvars:    []string{},
+		Filename:    "<string>",
+		Name:        "<module>",
+		Firstlineno: 1,
+		Lnotab:      "",
+	}, nil, ""},
 	{"def fn(a):\n    global b\n    b = a", "exec", &py.Code{
 		Argcount:       0,
 		Kwonlyargcount: 0,

compile/make_compile_test.py

@@ -176,6 +176,7 @@ def nested(d):
     ('''f(a, b, *args)''', "eval"),
     ('''f(a, b, *args, d=e, **kwargs)''', "eval"),
     ('''f(a, d=e, **kwargs)''', "eval"),
+    ('''f(a=1,a=2)''', "eval", SyntaxError),
     # return
     ('''return''', "exec", SyntaxError),
     # def
@@ -188,6 +189,7 @@ def nested(d):
     ('''def fn(a:"a",*arg:"arg",b:"b"=1,c:"c"=2,**kwargs:"kw") -> "ret": pass''', "exec"),
     ('''def fn(): a+b''', "exec"),
     ('''def fn(a,b): a+b+c+d''', "exec"),
+    ('''def fn(x,*,a,b): x+a+b''', "exec"),
     ('''\
 def fn(a):
     global b