4 files changed, 112 insertions, 1 deletions
diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go
index 32c342e545..3df84c5c94 100644
--- a/src/cmd/link/internal/loader/loader.go
+++ b/src/cmd/link/internal/loader/loader.go
@@ -434,7 +434,17 @@ func (l *Loader) AddSym(name string, ver int, r *oReader, li int, kind int, dupo
 		if l.flags&FlagStrictDups != 0 {
 			l.checkdup(name, r, li, oldi)
 		}
-		return oldi, false
+		// Fix for issue #46656 -- given two dupok symbols with
+		// different sizes, favor symbol with larger size.
+		szdup := l.SymSize(oldi)
+		sz := int64(r.Sym(li).Siz())
+		if szdup >= sz {
+			return oldi, false
+		} else {
+			// new symbol overwrites old symbol.
+			l.objSyms[oldi] = objSym{r, li}
+			return oldi, true
+		}
 	}
 	oldr, oldli := l.toLocal(oldi)
 	oldsym := oldr.Sym(oldli)
diff --git a/test/fixedbugs/issue46653.dir/bad/bad.go b/test/fixedbugs/issue46653.dir/bad/bad.go
new file mode 100644
index 0000000000..c1611b8347
--- /dev/null
+++ b/test/fixedbugs/issue46653.dir/bad/bad.go
@@ -0,0 +1,64 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func Bad() {
+	m := make(map[int64]A)
+	a := m[0]
+	if len(a.B.C1.D2.E2.F1) != 0 ||
+		len(a.B.C1.D2.E2.F2) != 0 ||
+		len(a.B.C1.D2.E2.F3) != 0 ||
+		len(a.B.C1.D2.E2.F4) != 0 ||
+		len(a.B.C1.D2.E2.F5) != 0 ||
+		len(a.B.C1.D2.E2.F6) != 0 ||
+		len(a.B.C1.D2.E2.F7) != 0 ||
+		len(a.B.C1.D2.E2.F8) != 0 ||
+		len(a.B.C1.D2.E2.F9) != 0 ||
+		len(a.B.C1.D2.E2.F10) != 0 ||
+		len(a.B.C1.D2.E2.F11) != 0 ||
+		len(a.B.C1.D2.E2.F16) != 0 {
+		panic("bad")
+	}
+}
+
+type A struct {
+	B
+}
+
+type B struct {
+	C1 C
+	C2 C
+}
+
+type C struct {
+	D1 D
+	D2 D
+}
+
+type D struct {
+	E1 E
+	E2 E
+	E3 E
+	E4 E
+}
+
+type E struct {
+	F1  string
+	F2  string
+	F3  string
+	F4  string
+	F5  string
+	F6  string
+	F7  string
+	F8  string
+	F9  string
+	F10 string
+	F11 string
+	F12 string
+	F13 string
+	F14 string
+	F15 string
+	F16 string
+}
diff --git a/test/fixedbugs/issue46653.dir/main.go b/test/fixedbugs/issue46653.dir/main.go
new file mode 100644
index 0000000000..e2a96e54ec
--- /dev/null
+++ b/test/fixedbugs/issue46653.dir/main.go
@@ -0,0 +1,27 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	bad "issue46653.dir/bad"
+)
+
+func main() {
+	bad.Bad()
+}
+
+func neverCalled() L {
+	m := make(map[string]L)
+	return m[""]
+}
+
+type L struct {
+	A Data
+	B Data
+}
+
+type Data struct {
+	F1 [22][]string
+}
diff --git a/test/fixedbugs/issue46653.go b/test/fixedbugs/issue46653.go
new file mode 100644
index 0000000000..e6283b1de5
--- /dev/null
+++ b/test/fixedbugs/issue46653.go
@@ -0,0 +1,10 @@
+// runindir
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test to verify compiler and linker handling of multiple
+// competing map.zero symbol definitions.
+
+package ignored