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Merged
merged 1 commit into from
Oct 6, 2025
Merged

Improve computed property lookup error messages #1179

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62 changes: 45 additions & 17 deletions quickjs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -530,6 +530,12 @@ typedef struct JSMapState {
resize is needed */
} JSMapState;

enum
{
JS_TO_STRING_IS_PROPERTY_KEY = 1 << 0,
JS_TO_STRING_NO_SIDE_EFFECTS = 1 << 1,
};

enum {
JS_ATOM_TYPE_STRING = 1,
JS_ATOM_TYPE_GLOBAL_SYMBOL,
Expand Down Expand Up @@ -1199,6 +1205,8 @@ static int JS_ToBoolFree(JSContext *ctx, JSValue val);
static int JS_ToInt32Free(JSContext *ctx, int32_t *pres, JSValue val);
static int JS_ToFloat64Free(JSContext *ctx, double *pres, JSValue val);
static int JS_ToUint8ClampFree(JSContext *ctx, int32_t *pres, JSValue val);
static JSValue JS_ToPropertyKeyInternal(JSContext *ctx, JSValueConst val,
int flags);
static JSValue js_new_string8_len(JSContext *ctx, const char *buf, int len);
static JSValue js_compile_regexp(JSContext *ctx, JSValueConst pattern,
JSValueConst flags);
Expand Down Expand Up @@ -8364,7 +8372,8 @@ static JSAtom js_symbol_to_atom(JSContext *ctx, JSValueConst val)
}

/* return JS_ATOM_NULL in case of exception */
JSAtom JS_ValueToAtom(JSContext *ctx, JSValueConst val)
static JSAtom JS_ValueToAtomInternal(JSContext *ctx, JSValueConst val,
int flags)
{
JSAtom atom;
uint32_t tag;
Expand All @@ -8378,7 +8387,7 @@ JSAtom JS_ValueToAtom(JSContext *ctx, JSValueConst val)
atom = JS_DupAtom(ctx, js_get_atom_index(ctx->rt, p));
} else {
JSValue str;
str = JS_ToPropertyKey(ctx, val);
str = JS_ToPropertyKeyInternal(ctx, val, flags);
if (JS_IsException(str))
return JS_ATOM_NULL;
if (JS_VALUE_GET_TAG(str) == JS_TAG_SYMBOL) {
Expand All @@ -8390,6 +8399,11 @@ JSAtom JS_ValueToAtom(JSContext *ctx, JSValueConst val)
return atom;
}

JSAtom JS_ValueToAtom(JSContext *ctx, JSValueConst val)
{
return JS_ValueToAtomInternal(ctx, val, /*flags*/0);
}

static bool js_get_fast_array_element(JSContext *ctx, JSObject *p,
uint32_t idx, JSValue *pval)
{
Expand Down Expand Up @@ -8466,15 +8480,21 @@ static JSValue JS_GetPropertyValue(JSContext *ctx, JSValueConst this_obj,
if (js_get_fast_array_element(ctx, p, idx, &val))
return val;
}
} else {
switch(tag) {
case JS_TAG_NULL:
JS_FreeValue(ctx, prop);
return JS_ThrowTypeError(ctx, "cannot read property of null");
case JS_TAG_UNDEFINED:
JS_FreeValue(ctx, prop);
return JS_ThrowTypeError(ctx, "cannot read property of undefined");
} else if (unlikely(tag == JS_TAG_NULL || tag == JS_TAG_UNDEFINED)) {
// per spec: not allowed to call ToPropertyKey before ToObject
// so we must ensure to not invoke JS anything that's observable
// from JS code
atom = JS_ValueToAtomInternal(ctx, prop, JS_TO_STRING_NO_SIDE_EFFECTS);
JS_FreeValue(ctx, prop);
if (unlikely(atom == JS_ATOM_NULL))
return JS_EXCEPTION;
if (tag == JS_TAG_NULL) {
JS_ThrowTypeErrorAtom(ctx, "cannot read property '%s' of null", atom);
} else {
JS_ThrowTypeErrorAtom(ctx, "cannot read property '%s' of undefined", atom);
}
JS_FreeAtom(ctx, atom);
return JS_EXCEPTION;
}
atom = JS_ValueToAtom(ctx, prop);
JS_FreeValue(ctx, prop);
Expand Down Expand Up @@ -12887,8 +12907,8 @@ static JSValue js_dtoa2(JSContext *ctx,
return res;
}

JSValue JS_ToStringInternal(JSContext *ctx, JSValueConst val,
bool is_ToPropertyKey)
static JSValue JS_ToStringInternal(JSContext *ctx, JSValueConst val,
int flags)
{
uint32_t tag;
char buf[32];
Expand All @@ -12911,20 +12931,22 @@ JSValue JS_ToStringInternal(JSContext *ctx, JSValueConst val,
case JS_TAG_EXCEPTION:
return JS_EXCEPTION;
case JS_TAG_OBJECT:
{
if (flags & JS_TO_STRING_NO_SIDE_EFFECTS) {
return js_new_string8(ctx, "{}");
} else {
JSValue val1, ret;
val1 = JS_ToPrimitive(ctx, val, HINT_STRING);
if (JS_IsException(val1))
return val1;
ret = JS_ToStringInternal(ctx, val1, is_ToPropertyKey);
ret = JS_ToStringInternal(ctx, val1, flags);
JS_FreeValue(ctx, val1);
return ret;
}
break;
case JS_TAG_FUNCTION_BYTECODE:
return js_new_string8(ctx, "[function bytecode]");
case JS_TAG_SYMBOL:
if (is_ToPropertyKey) {
if (flags & JS_TO_STRING_IS_PROPERTY_KEY) {
return js_dup(val);
} else {
return JS_ThrowTypeError(ctx, "cannot convert symbol to string");
Expand All @@ -12944,7 +12966,7 @@ JSValue JS_ToStringInternal(JSContext *ctx, JSValueConst val,

JSValue JS_ToString(JSContext *ctx, JSValueConst val)
{
return JS_ToStringInternal(ctx, val, false);
return JS_ToStringInternal(ctx, val, /*flags*/0);
}

static JSValue JS_ToStringFree(JSContext *ctx, JSValue val)
Expand All @@ -12962,9 +12984,15 @@ static JSValue JS_ToLocaleStringFree(JSContext *ctx, JSValue val)
return JS_InvokeFree(ctx, val, JS_ATOM_toLocaleString, 0, NULL);
}

static JSValue JS_ToPropertyKeyInternal(JSContext *ctx, JSValueConst val,
int flags)
{
return JS_ToStringInternal(ctx, val, flags | JS_TO_STRING_IS_PROPERTY_KEY);
}

JSValue JS_ToPropertyKey(JSContext *ctx, JSValueConst val)
{
return JS_ToStringInternal(ctx, val, true);
return JS_ToPropertyKeyInternal(ctx, val, /*flags*/0);
}

static JSValue JS_ToStringCheckObject(JSContext *ctx, JSValueConst val)
Expand Down
38 changes: 38 additions & 0 deletions tests/null_or_undefined.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,38 @@
import {assert} from "./assert.js"

let ex
try {
null.x
} catch (e) {
ex = e
}
assert(ex instanceof TypeError)
assert(ex.message, "cannot read property 'x' of null")
ex = undefined

try {
null["x"]
} catch (e) {
ex = e
}
assert(ex instanceof TypeError)
assert(ex.message, "cannot read property 'x' of null")
ex = undefined

try {
undefined.x
} catch (e) {
ex = e
}
assert(ex instanceof TypeError)
assert(ex.message, "cannot read property 'x' of undefined")
ex = undefined

try {
undefined["x"]
} catch (e) {
ex = e
}
assert(ex instanceof TypeError)
assert(ex.message, "cannot read property 'x' of undefined")
ex = undefined