From d8ad096698cd9fc2fc285fbd6b51b24cc482c7f2 Mon Sep 17 00:00:00 2001
From: fabriziopapi <fabrizio.papi@pagopa.it>
Date: Thu, 20 May 2021 12:17:29 +0200
Subject: [PATCH 1/2] Fixed issue about decoding an Intersection composed by a
 type and a type composed by an empty interface and another type

---
 docs/modules/index.ts.md |  2 +-
 src/index.ts             | 21 ++++++++-------------
 2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/docs/modules/index.ts.md b/docs/modules/index.ts.md
index 6d42e2077..d4ede0f94 100644
--- a/docs/modules/index.ts.md
+++ b/docs/modules/index.ts.md
@@ -1827,7 +1827,7 @@ export const array = <C extends Mixed>(codec: C, name: string = `Array<${codec.n
     name,
     (u): u is Array<TypeOf<C>> => UnknownArray.is(u) && u.every(codec.is),
     (u, c) =>
-      chain(UnknownArray.validate(u, c), us => ...
+      UnknownArray.validate(u, c).chain(us => ...
 ```
 
 Added in v1.0.0
diff --git a/src/index.ts b/src/index.ts
index a20ac9cf6..cc588e2c4 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1168,19 +1168,14 @@ export interface IntersectionC<CS extends [Mixed, Mixed, ...Array<Mixed>]>
   > {}
 
 const mergeAll = (base: any, us: Array<any>): any => {
-  let r: any = base
-  for (let i = 0; i < us.length; i++) {
-    const u = us[i]
-    if (u !== base) {
-      // `u` contains a prismatic value or is the result of a stripping combinator
-      if (r === base) {
-        r = Object.assign({}, u)
-        continue
-      }
-      for (const k in u) {
-        if (u[k] !== base[k] || !r.hasOwnProperty(k)) {
-          r[k] = u[k]
-        }
+  if (!us.some(u => u !== base)) {
+    return base
+  }
+  const r: any = {}
+  for (const u of us) {
+    for (const k in u) {
+      if (!r.hasOwnProperty(k) || u[k] !== base[k]) {
+        r[k] = u[k]
       }
     }
   }

From b10c1ad5bc60b646660e48e5e678305bea7f7668 Mon Sep 17 00:00:00 2001
From: fabriziopapi <fabrizio.papi@pagopa.it>
Date: Thu, 20 May 2021 15:25:51 +0200
Subject: [PATCH 2/2] test for intersection with inner exact of a empty
 interface

---
 test/exact.ts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/test/exact.ts b/test/exact.ts
index b0b6bed03..78871482e 100644
--- a/test/exact.ts
+++ b/test/exact.ts
@@ -51,6 +51,16 @@ describe('exact', () => {
       assertSuccess(T.decode({ foo: 'foo' }))
     })
 
+    it('should succeed validating a valid value (intersection with inner exact of a empty interface)', () => {
+      const T = t.intersection([
+        t.type({ foo: t.string }),
+        t.exact(t.intersection([t.interface({}), t.partial({ bar: t.number })]))
+      ])
+      assertSuccess(T.decode({ foo: 'foo', bar: 1 }))
+      assertSuccess(T.decode({ foo: 'foo', bar: undefined }))
+      assertSuccess(T.decode({ foo: 'foo' }), { foo: 'foo' })
+    })
+
     it('should succeed validating a valid value (refinement)', () => {
       // tslint:disable-next-line: deprecation
       const T = t.exact(t.refinement(t.type({ foo: t.string }), p => p.foo.length > 2))