internal/shader: add type checks for the builtin function mix

Updates #2184

internal/shader/expr.go

@@ -450,7 +450,7 @@ func (cs *compileState) parseExpr(block *block, fname string, expr ast.Expr, mar
 				})
 				return nil, nil, stmts, true
 
-			case shaderir.Clamp:
+			case shaderir.Clamp, shaderir.Mix:
 				// 3 arguments
 				if len(args) != 3 {
 					cs.addError(e.Pos(), fmt.Sprintf("number of %s's arguments must be 3 but %d", callee.BuiltinFunc, len(args)))
@@ -468,10 +468,22 @@ func (cs *compileState) parseExpr(block *block, fname string, expr ast.Expr, mar
 						return nil, nil, nil, false
 					}
 				}
+				switch callee.BuiltinFunc {
+				case shaderir.Clamp:
 					if (!argts[0].Equal(&argts[1]) || !argts[0].Equal(&argts[2])) && (argts[1].Main != shaderir.Float || argts[2].Main != shaderir.Float) {
 						cs.addError(e.Pos(), fmt.Sprintf("the second and the third arguments for %s must equal to the first argument %s or float but %s and %s", callee.BuiltinFunc, argts[0].String(), argts[1].String(), argts[2].String()))
 						return nil, nil, nil, false
 					}
+				case shaderir.Mix:
+					if !argts[0].Equal(&argts[1]) {
+						cs.addError(e.Pos(), fmt.Sprintf("%s and %s don't match in argument to %s", argts[0].String(), argts[1].String(), callee.BuiltinFunc))
+						return nil, nil, nil, false
+					}
+					if !argts[0].Equal(&argts[2]) && argts[2].Main != shaderir.Float {
+						cs.addError(e.Pos(), fmt.Sprintf("the third arguments for %s must equal to the first/second argument %s or float but %s", callee.BuiltinFunc, argts[0].String(), argts[2].String()))
+						return nil, nil, nil, false
+					}
+				}
 
 				t = argts[0]
 

internal/shader/syntax_test.go

@@ -1873,6 +1873,58 @@ func TestSyntaxBuiltinFuncClampType(t *testing.T) {
 		{stmt: "a := clamp(vec4(1), 1, vec4(1)); _ = a", err: true},
 		{stmt: "a := clamp(vec4(1), vec4(1), 1); _ = a", err: true},
 		{stmt: "a := clamp(vec4(1), vec4(1), vec4(1)); _ = a", err: false},
+		{stmt: "a := clamp(1, 1, 1, 1); _ = a", err: true},
+	}
+
+	for _, c := range cases {
+		stmt := c.stmt
+		src := fmt.Sprintf(`package main
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	%s
+	return position
+}`, stmt)
+		_, err := compileToIR([]byte(src))
+		if err == nil && c.err {
+			t.Errorf("%s must return an error but does not", stmt)
+		} else if err != nil && !c.err {
+			t.Errorf("%s must not return nil but returned %v", stmt, err)
+		}
+	}
+}
+
+// Issue #2184
+func TestSyntaxBuiltinFuncMixType(t *testing.T) {
+	cases := []struct {
+		stmt string
+		err  bool
+	}{
+		{stmt: "a := mix(); _ = a", err: true},
+		{stmt: "a := mix(1); _ = a", err: true},
+		{stmt: "a := mix(false, false); _ = a", err: true},
+		{stmt: "a := mix(1, 1); _ = a", err: true},
+		{stmt: "a := mix(false, false, false); _ = a", err: true},
+		{stmt: "a := mix(1, 1, 1); _ = a", err: false},
+		{stmt: "a := mix(1.0, 1, 1); _ = a", err: false},
+		{stmt: "a := mix(1, 1.0, 1); _ = a", err: false},
+		{stmt: "a := mix(1, 1, 1.0); _ = a", err: false},
+		{stmt: "a := mix(1, vec2(1), 1); _ = a", err: true},
+		{stmt: "a := mix(1, 1, vec2(1)); _ = a", err: true},
+		{stmt: "a := mix(1, vec2(1), vec2(1)); _ = a", err: true},
+		{stmt: "a := mix(vec2(1), 1, 1); _ = a", err: true},
+		{stmt: "a := mix(vec2(1), 1, vec2(1)); _ = a", err: true},
+		{stmt: "a := mix(vec2(1), vec2(1), 1); _ = a", err: false}, // The thrid argument can be a float.
+		{stmt: "a := mix(vec2(1), vec2(1), vec2(1)); _ = a", err: false},
+		{stmt: "a := mix(vec2(1), vec2(1), vec3(1)); _ = a", err: true},
+		{stmt: "a := mix(vec3(1), 1, 1); _ = a", err: true},
+		{stmt: "a := mix(vec3(1), 1, vec3(1)); _ = a", err: true},
+		{stmt: "a := mix(vec3(1), vec3(1), 1); _ = a", err: false}, // The thrid argument can be a float.
+		{stmt: "a := mix(vec3(1), vec3(1), vec3(1)); _ = a", err: false},
+		{stmt: "a := mix(vec4(1), 1, 1); _ = a", err: true},
+		{stmt: "a := mix(vec4(1), 1, vec4(1)); _ = a", err: true},
+		{stmt: "a := mix(vec4(1), vec4(1), 1); _ = a", err: false}, // The thrid argument can be a float.
+		{stmt: "a := mix(vec4(1), vec4(1), vec4(1)); _ = a", err: false},
+		{stmt: "a := mix(1, 1, 1, 1); _ = a", err: true},
 	}
 
 	for _, c := range cases {