From 80f4ce2d036f0f973b55a7e227a986498d1e6160 Mon Sep 17 00:00:00 2001
From: sen2y <pse6704@sookmyung.ac.kr>
Date: Wed, 1 Oct 2025 21:29:20 +0900
Subject: [PATCH 1/3] fix(isMatch): handle primitive targets with object source
 patterns correctly

---
 src/compat/predicate/isMatch.spec.ts | 18 ++++++++++++++++++
 src/compat/predicate/isMatchWith.ts  |  7 +++++++
 2 files changed, 25 insertions(+)

diff --git a/src/compat/predicate/isMatch.spec.ts b/src/compat/predicate/isMatch.spec.ts
index 073ca4d79..58213df20 100644
--- a/src/compat/predicate/isMatch.spec.ts
+++ b/src/compat/predicate/isMatch.spec.ts
@@ -316,6 +316,24 @@ describe('isMatch', () => {
     delete numberProto.b;
   });
 
+  it('should return `false` when target is primitive and source is object with undefined values (Issue #1399)', () => {
+    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+    // @ts-expect-error
+    expect(isMatch('bar', { anyKey: undefined })).toBe(false);
+    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+    // @ts-expect-error
+    expect(isMatch(123, { anyKey: undefined })).toBe(false);
+    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+    // @ts-expect-error
+    expect(isMatch(true, { anyKey: undefined })).toBe(false);
+  });
+
+  it('should return `false` when target is primitive and source is empty object nested (Issue #1399)', () => {
+    expect(isMatch({ value: 'bar' }, { value: {} })).toBe(false);
+    expect(isMatch({ value: 123 }, { value: {} })).toBe(false);
+    expect(isMatch({ value: true }, { value: {} })).toBe(false);
+  });
+
   it(`should return \`false\` when \`object\` is nullish`, () => {
     // eslint-disable-next-line no-sparse-arrays
     const values = [, null, undefined];
diff --git a/src/compat/predicate/isMatchWith.ts b/src/compat/predicate/isMatchWith.ts
index 6c2a7f192..990da6228 100644
--- a/src/compat/predicate/isMatchWith.ts
+++ b/src/compat/predicate/isMatchWith.ts
@@ -211,9 +211,16 @@ function isObjectMatch(
   }
 
   if (keys.length === 0) {
+    if (stack && stack.size > 0 && !isObject(target)) {
+      return false;
+    }
     return true;
   }
 
+  if (!isObject(target)) {
+    return false;
+  }
+
   if (stack && stack.has(source)) {
     return stack.get(source) === target;
   }

From 2346eeae030f1c9343969b661dc22f8075fbb0f4 Mon Sep 17 00:00:00 2001
From: Sojin Park <raon0211@gmail.com>
Date: Fri, 24 Oct 2025 12:32:08 +0900
Subject: [PATCH 2/3] Update src/compat/predicate/isMatchWith.ts

---
 src/compat/predicate/isMatchWith.ts | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/compat/predicate/isMatchWith.ts b/src/compat/predicate/isMatchWith.ts
index 990da6228..1fa02672c 100644
--- a/src/compat/predicate/isMatchWith.ts
+++ b/src/compat/predicate/isMatchWith.ts
@@ -210,17 +210,14 @@ function isObjectMatch(
     return keys.length === 0;
   }
 
-  if (keys.length === 0) {
-    if (stack && stack.size > 0 && !isObject(target)) {
-      return false;
-    }
-    return true;
-  }
-
   if (!isObject(target)) {
     return false;
   }
 
+  if (keys.length === 0) {
+    return true;
+  }
+
   if (stack && stack.has(source)) {
     return stack.get(source) === target;
   }

From df2b90783bb9905f8b22539f7f7fc5362526a713 Mon Sep 17 00:00:00 2001
From: Sojin Park <raon0211@gmail.com>
Date: Fri, 24 Oct 2025 12:35:31 +0900
Subject: [PATCH 3/3] Update src/compat/predicate/isMatchWith.ts

---
 src/compat/predicate/isMatchWith.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/compat/predicate/isMatchWith.ts b/src/compat/predicate/isMatchWith.ts
index 1fa02672c..4287a9554 100644
--- a/src/compat/predicate/isMatchWith.ts
+++ b/src/compat/predicate/isMatchWith.ts
@@ -207,7 +207,10 @@ function isObjectMatch(
   const keys = Object.keys(source as any);
 
   if (target == null) {
-    return keys.length === 0;
+    if (stack && stack.size > 0 && !isObject(target)) {
+      return false;
+    }
+    return true;
   }
 
   if (!isObject(target)) {