diff --git a/src/cmd/compile/internal/importer/iimport.go b/src/cmd/compile/internal/importer/iimport.go
index a827987a48..bed4fbb016 100644
--- a/src/cmd/compile/internal/importer/iimport.go
+++ b/src/cmd/compile/internal/importer/iimport.go
@@ -180,6 +180,14 @@ func ImportData(imports map[string]*types2.Package, data, path string) (pkg *typ
 		p.doDecl(localpkg, name)
 	}
 
+	// SetConstraint can't be called if the constraint type is not yet complete.
+	// When type params are created in the 'P' case of (*importReader).obj(),
+	// the associated constraint type may not be complete due to recursion.
+	// Therefore, we defer calling SetConstraint there, and call it here instead
+	// after all types are complete.
+	for _, d := range p.later {
+		d.t.SetConstraint(d.constraint)
+	}
 	// record all referenced packages as imports
 	list := append(([]*types2.Package)(nil), pkgList[1:]...)
 	sort.Sort(byPath(list))
@@ -191,6 +199,11 @@ func ImportData(imports map[string]*types2.Package, data, path string) (pkg *typ
 	return localpkg, nil
 }
 
+type setConstraintArgs struct {
+	t          *types2.TypeParam
+	constraint types2.Type
+}
+
 type iimporter struct {
 	exportVersion int64
 	ipath         string
@@ -206,6 +219,9 @@ type iimporter struct {
 	tparamIndex map[ident]*types2.TypeParam
 
 	interfaceList []*types2.Interface
+
+	// Arguments for calls to SetConstraint that are deferred due to recursive types
+	later []setConstraintArgs
 }
 
 func (p *iimporter) doDecl(pkg *types2.Package, name string) {
@@ -401,7 +417,11 @@ func (r *importReader) obj(name string) {
 			}
 			iface.MarkImplicit()
 		}
-		t.SetConstraint(constraint)
+		// The constraint type may not be complete, if we
+		// are in the middle of a type recursion involving type
+		// constraints. So, we defer SetConstraint until we have
+		// completely set up all types in ImportData.
+		r.p.later = append(r.p.later, setConstraintArgs{t: t, constraint: constraint})
 
 	case 'V':
 		typ := r.typ()
diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index bc34d3933a..ef91f550a5 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -354,15 +354,18 @@ func (r *importReader) doDecl(sym *types.Sym) *ir.Name {
 		// declaration before recursing.
 		n := importtype(pos, sym)
 		t := n.Type()
+
+		// Because of recursion, we need to defer width calculations and
+		// instantiations on intermediate types until the top-level type is
+		// fully constructed. Note that we can have recursion via type
+		// constraints.
+		types.DeferCheckSize()
+		deferDoInst()
 		if tag == 'U' {
 			rparams := r.typeList()
 			t.SetRParams(rparams)
 		}
 
-		// We also need to defer width calculations until
-		// after the underlying type has been assigned.
-		types.DeferCheckSize()
-		deferDoInst()
 		underlying := r.typ()
 		t.SetUnderlying(underlying)
 
diff --git a/src/go/internal/gcimporter/iimport.go b/src/go/internal/gcimporter/iimport.go
index 8ec4c5413b..bff1c09cc9 100644
--- a/src/go/internal/gcimporter/iimport.go
+++ b/src/go/internal/gcimporter/iimport.go
@@ -181,6 +181,15 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataRea
 		p.doDecl(localpkg, name)
 	}
 
+	// SetConstraint can't be called if the constraint type is not yet complete.
+	// When type params are created in the 'P' case of (*importReader).obj(),
+	// the associated constraint type may not be complete due to recursion.
+	// Therefore, we defer calling SetConstraint there, and call it here instead
+	// after all types are complete.
+	for _, d := range p.later {
+		d.t.SetConstraint(d.constraint)
+	}
+
 	for _, typ := range p.interfaceList {
 		typ.Complete()
 	}
@@ -195,6 +204,11 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataRea
 	return localpkg, nil
 }
 
+type setConstraintArgs struct {
+	t          *types.TypeParam
+	constraint types.Type
+}
+
 type iimporter struct {
 	exportVersion int64
 	ipath         string
@@ -211,6 +225,9 @@ type iimporter struct {
 
 	fake          fakeFileSet
 	interfaceList []*types.Interface
+
+	// Arguments for calls to SetConstraint that are deferred due to recursive types
+	later []setConstraintArgs
 }
 
 func (p *iimporter) doDecl(pkg *types.Package, name string) {
@@ -391,7 +408,11 @@ func (r *importReader) obj(name string) {
 			}
 			iface.MarkImplicit()
 		}
-		t.SetConstraint(constraint)
+		// The constraint type may not be complete, if we
+		// are in the middle of a type recursion involving type
+		// constraints. So, we defer SetConstraint until we have
+		// completely set up all types in ImportData.
+		r.p.later = append(r.p.later, setConstraintArgs{t: t, constraint: constraint})
 
 	case 'V':
 		typ := r.typ()
diff --git a/test/typeparam/issue51219.dir/a.go b/test/typeparam/issue51219.dir/a.go
new file mode 100644
index 0000000000..3ed4322dbf
--- /dev/null
+++ b/test/typeparam/issue51219.dir/a.go
@@ -0,0 +1,59 @@
+// Copyright 2022 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
+
+// Type I is the first basic test for the issue, which relates to a type that is recursive
+// via a type constraint.  (In this test, I -> IConstraint -> MyStruct -> I.)
+type JsonRaw []byte
+
+type MyStruct struct {
+	x *I[JsonRaw]
+}
+
+type IConstraint interface {
+	JsonRaw | MyStruct
+}
+
+type I[T IConstraint] struct {
+}
+
+// The following types form an even more complex recursion (through two type
+// constraints), and model the actual types in the issue (#51219) more closely.
+// However, they don't reveal any new issue. But it seems useful to leave this
+// complex set of types in a test in case it might be broken by future changes.
+
+type Message struct {
+	Interaction *Interaction[JsonRaw] `json:"interaction,omitempty"`
+}
+
+type ResolvedDataConstraint interface {
+	User | Message
+}
+
+type Snowflake uint64
+
+type ResolvedData[T ResolvedDataConstraint] map[Snowflake]T
+
+type User struct {
+}
+
+type Resolved struct {
+	Users ResolvedData[User] `json:"users,omitempty"`
+}
+
+type resolvedInteractionWithOptions struct {
+	Resolved Resolved `json:"resolved,omitempty"`
+}
+
+type UserCommandInteractionData struct {
+	resolvedInteractionWithOptions
+}
+
+type InteractionDataConstraint interface {
+	JsonRaw | UserCommandInteractionData
+}
+
+type Interaction[DataT InteractionDataConstraint] struct {
+}
diff --git a/test/typeparam/issue51219.dir/b.go b/test/typeparam/issue51219.dir/b.go
new file mode 100644
index 0000000000..c1590725b0
--- /dev/null
+++ b/test/typeparam/issue51219.dir/b.go
@@ -0,0 +1,11 @@
+// Copyright 2022 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 b
+
+import "a"
+
+type InteractionRequest[T a.InteractionDataConstraint] struct {
+	a.Interaction[T]
+}
diff --git a/test/typeparam/issue51219.dir/main.go b/test/typeparam/issue51219.dir/main.go
new file mode 100644
index 0000000000..c5cffd111c
--- /dev/null
+++ b/test/typeparam/issue51219.dir/main.go
@@ -0,0 +1,18 @@
+// Copyright 2022 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 (
+	"a"
+	"b"
+	"fmt"
+)
+
+func main() {
+	var x a.I[a.JsonRaw]
+	var y b.InteractionRequest[a.JsonRaw]
+
+	fmt.Printf("%v %v\n", x, y)
+}
diff --git a/test/typeparam/issue51219.go b/test/typeparam/issue51219.go
new file mode 100644
index 0000000000..642f4bf49f
--- /dev/null
+++ b/test/typeparam/issue51219.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2022 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 ignored
diff --git a/test/typeparam/issue51219.out b/test/typeparam/issue51219.out
new file mode 100644
index 0000000000..99c5b9aa9b
--- /dev/null
+++ b/test/typeparam/issue51219.out
@@ -0,0 +1 @@
+{} {{}}