diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index 46b184f53c..8133e963d7 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -474,52 +474,54 @@ func TestInstanceInfo(t *testing.T) {
 		// 	`func(float64)`,
 		// },
 
-		{`package s1; func f[T any, P interface{~*T}](x T) {}; func _(x string) { f(x) }`,
+		{`package s1; func f[T any, P interface{*T}](x T) {}; func _(x string) { f(x) }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func(x string)`,
 		},
-		{`package s2; func f[T any, P interface{~*T}](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s2; func f[T any, P interface{*T}](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `*int`},
 			`func(x []int)`,
 		},
-		{`package s3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s3; type C[T any] interface{chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`},
 			`func(x []int)`,
 		},
-		{`package s4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func(x []int)`,
 		},
 
-		{`package t1; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = f[string] }`,
+		{`package t1; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = f[string] }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func() string`,
 		},
-		{`package t2; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
+		{`package t2; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func() string`,
 		},
-		{`package t3; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
+		{`package t3; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func() []int`,
 		},
-		{`package t4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
+		{`package t4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = (f[int]) }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func() []int`,
 		},
-		{`package i0; import lib "generic_lib"; func _() { lib.F(42) }`,
+
+		{`package i0; import "lib"; func _() { lib.F(42) }`,
 			`F`,
 			[]string{`int`},
 			`func(int)`,
 		},
+
 		{`package type0; type T[P interface{~int}] struct{ x P }; var _ T[int]`,
 			`T`,
 			[]string{`int`},
@@ -540,7 +542,7 @@ func TestInstanceInfo(t *testing.T) {
 			[]string{`[]int`, `int`},
 			`struct{x []int; y int}`,
 		},
-		{`package type4; import lib "generic_lib"; var _ lib.T[int]`,
+		{`package type4; import "lib"; var _ lib.T[int]`,
 			`T`,
 			[]string{`int`},
 			`[]int`,
@@ -548,7 +550,7 @@ func TestInstanceInfo(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		const lib = `package generic_lib
+		const lib = `package lib
 
 func F[P any](P) {}
 
diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index 617f3edad7..29633028f3 100644
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -488,21 +488,88 @@ func (check *Checker) inferB(pos syntax.Pos, tparams []*TypeParam, targs []Type)
 		}
 	}
 
-	// If a constraint has a core type, unify the corresponding type parameter with it.
-	for _, tpar := range tparams {
-		if ctype := adjCoreType(tpar); ctype != nil {
-			if !u.unify(tpar, ctype) {
-				// TODO(gri) improve error message by providing the type arguments
-				//           which we know already
-				check.errorf(pos, "%s does not match %s", tpar, ctype)
-				return nil, 0
+	// Repeatedly apply constraint type inference as long as
+	// there are still unknown type arguments and progress is
+	// being made.
+	//
+	// This is an O(n^2) algorithm where n is the number of
+	// type parameters: if there is progress (and iteration
+	// continues), at least one type argument is inferred
+	// per iteration and we have a doubly nested loop.
+	// In practice this is not a problem because the number
+	// of type parameters tends to be very small (< 5 or so).
+	// (It should be possible for unification to efficiently
+	// signal newly inferred type arguments; then the loops
+	// here could handle the respective type parameters only,
+	// but that will come at a cost of extra complexity which
+	// may not be worth it.)
+	for n := u.x.unknowns(); n > 0; {
+		nn := n
+
+		for i, tpar := range tparams {
+			// If there is a core term (i.e., a core type with tilde information)
+			// unify the type parameter with the core type.
+			if core, single := coreTerm(tpar); core != nil {
+				// A type parameter can be unified with its core type in two cases.
+				tx := u.x.at(i)
+				switch {
+				case tx != nil:
+					// The corresponding type argument tx is known.
+					// In this case, if the core type has a tilde, the type argument's underlying
+					// type must match the core type, otherwise the type argument and the core type
+					// must match.
+					// If tx is an external type parameter, don't consider its underlying type
+					// (which is an interface). Core type unification will attempt to unify against
+					// core.typ.
+					// Note also that even with inexact unification we cannot leave away the under
+					// call here because it's possible that both tx and core.typ are named types,
+					// with under(tx) being a (named) basic type matching core.typ. Such cases do
+					// not match with inexact unification.
+					if core.tilde && !isTypeParam(tx) {
+						tx = under(tx)
+					}
+					if !u.unify(tx, core.typ) {
+						// TODO(gri) improve error message by providing the type arguments
+						//           which we know already
+						// Don't use term.String() as it always qualifies types, even if they
+						// are in the current package.
+						tilde := ""
+						if core.tilde {
+							tilde = "~"
+						}
+						check.errorf(pos, "%s does not match %s%s", tpar, tilde, core.typ)
+						return nil, 0
+					}
+
+				case single && !core.tilde:
+					// The corresponding type argument tx is unknown and there's a single
+					// specific type and no tilde.
+					// In this case the type argument must be that single type; set it.
+					u.x.set(i, core.typ)
+
+				default:
+					// Unification is not possible and no progress was made.
+					continue
+				}
+
+				// The number of known type arguments may have changed.
+				nn = u.x.unknowns()
+				if nn == 0 {
+					break // all type arguments are known
+				}
 			}
 		}
+
+		assert(nn <= n)
+		if nn == n {
+			break // no progress
+		}
+		n = nn
 	}
 
 	// u.x.types() now contains the incoming type arguments plus any additional type
-	// arguments which were inferred from core types. The newly inferred non-
-	// nil entries may still contain references to other type parameters.
+	// arguments which were inferred from core terms. The newly inferred non-nil
+	// entries may still contain references to other type parameters.
 	// For instance, for [A any, B interface{ []C }, C interface{ *A }], if A == int
 	// was given, unification produced the type list [int, []C, *A]. We eliminate the
 	// remaining type parameters by substituting the type parameters in this type list
@@ -591,26 +658,40 @@ func (check *Checker) inferB(pos syntax.Pos, tparams []*TypeParam, targs []Type)
 	return
 }
 
-// adjCoreType returns the core type of tpar unless the
-// type parameter embeds a single, possibly named type,
-// in which case it returns that single type instead.
-// (The core type is always the underlying type of that
-// single type.)
-func adjCoreType(tpar *TypeParam) Type {
-	var single *term
-	if tpar.is(func(t *term) bool {
-		if single == nil && t != nil {
-			single = t
-			return true
+// If the type parameter has a single specific type S, coreTerm returns (S, true).
+// Otherwise, if tpar has a core type T, it returns a term corresponding to that
+// core type and false. In that case, if any term of tpar has a tilde, the core
+// term has a tilde. In all other cases coreTerm returns (nil, false).
+func coreTerm(tpar *TypeParam) (*term, bool) {
+	n := 0
+	var single *term // valid if n == 1
+	var tilde bool
+	tpar.is(func(t *term) bool {
+		if t == nil {
+			assert(n == 0)
+			return false // no terms
 		}
-		return false // zero or more than one terms
-	}) {
+		n++
+		single = t
+		if t.tilde {
+			tilde = true
+		}
+		return true
+	})
+	if n == 1 {
 		if debug {
-			assert(under(single.typ) == coreType(tpar))
+			assert(debug && under(single.typ) == coreType(tpar))
 		}
-		return single.typ
+		return single, true
 	}
-	return coreType(tpar)
+	if typ := coreType(tpar); typ != nil {
+		// A core type is always an underlying type.
+		// If any term of tpar has a tilde, we don't
+		// have a precise core type and we must return
+		// a tilde as well.
+		return &term{tilde, typ}, false
+	}
+	return nil, false
 }
 
 type cycleFinder struct {
diff --git a/src/cmd/compile/internal/types2/testdata/check/funcinference.go2 b/src/cmd/compile/internal/types2/testdata/check/funcinference.go2
index 7160e18b19..45d0781cd7 100644
--- a/src/cmd/compile/internal/types2/testdata/check/funcinference.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/funcinference.go2
@@ -8,21 +8,21 @@ import "strconv"
 
 type any interface{}
 
-func f0[A any, B interface{~*C}, C interface{~*D}, D interface{~*A}](A, B, C, D) {}
+func f0[A any, B interface{*C}, C interface{*D}, D interface{*A}](A, B, C, D) {}
 func _() {
 	f := f0[string]
 	f("a", nil, nil, nil)
 	f0("a", nil, nil, nil)
 }
 
-func f1[A any, B interface{~*A}](A, B) {}
+func f1[A any, B interface{*A}](A, B) {}
 func _() {
 	f := f1[int]
 	f(int(0), new(int))
 	f1(int(0), new(int))
 }
 
-func f2[A any, B interface{~[]A}](A, B) {}
+func f2[A any, B interface{[]A}](A, B) {}
 func _() {
 	f := f2[byte]
 	f(byte(0), []byte{})
@@ -38,7 +38,7 @@ func _() {
 // 	f3(x, &x, &x)
 // }
 
-func f4[A any, B interface{~[]C}, C interface{~*A}](A, B, C) {}
+func f4[A any, B interface{[]C}, C interface{*A}](A, B, C) {}
 func _() {
 	f := f4[int]
 	var x int
@@ -46,7 +46,7 @@ func _() {
 	f4(x, []*int{}, &x)
 }
 
-func f5[A interface{~struct{b B; c C}}, B any, C interface{~*B}](x B) A { panic(0) }
+func f5[A interface{struct{b B; c C}}, B any, C interface{*B}](x B) A { panic(0) }
 func _() {
 	x := f5(1.2)
 	var _ float64 = x.b
@@ -79,14 +79,14 @@ var _ = Double(MySlice{1})
 
 type Setter[B any] interface {
 	Set(string)
-	~*B
+	*B
 }
 
 func FromStrings[T interface{}, PT Setter[T]](s []string) []T {
 	result := make([]T, len(s))
 	for i, v := range s {
 		// The type of &result[i] is *T which is in the type list
-		// of Setter2, so we can convert it to PT.
+		// of Setter, so we can convert it to PT.
 		p := PT(&result[i])
 		// PT has a Set method.
 		p.Set(v)
diff --git a/src/cmd/compile/internal/types2/testdata/check/typeinference.go2 b/src/cmd/compile/internal/types2/testdata/check/typeinference.go2
index 8876ccaa4e..3d3380da9c 100644
--- a/src/cmd/compile/internal/types2/testdata/check/typeinference.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/typeinference.go2
@@ -14,7 +14,7 @@ func _() {
 }
 
 // recursive inference
-type Tr[A any, B ~*C, C ~*D, D ~*A] int
+type Tr[A any, B *C, C *D, D *A] int
 func _() {
 	var x Tr[string]
 	var y Tr[string, ***string, **string, *string]
@@ -25,11 +25,11 @@ func _() {
 }
 
 // other patterns of inference
-type To0[A any, B ~[]A] int
-type To1[A any, B ~struct{a A}] int
-type To2[A any, B ~[][]A] int
-type To3[A any, B ~[3]*A] int
-type To4[A any, B any, C ~struct{a A; b B}] int
+type To0[A any, B []A] int
+type To1[A any, B struct{a A}] int
+type To2[A any, B [][]A] int
+type To3[A any, B [3]*A] int
+type To4[A any, B any, C struct{a A; b B}] int
 func _() {
 	var _ To0[int]
 	var _ To1[int]
diff --git a/src/cmd/compile/internal/types2/testdata/examples/inference.go2 b/src/cmd/compile/internal/types2/testdata/examples/inference.go2
index e762f33605..e3d6bfb212 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/inference.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/inference.go2
@@ -78,7 +78,7 @@ func _() {
 	related1(si, "foo" /* ERROR cannot use "foo" */ )
 }
 
-func related2[Elem any, Slice interface{~[]Elem}](e Elem, s Slice) {}
+func related2[Elem any, Slice interface{[]Elem}](e Elem, s Slice) {}
 
 func _() {
 	// related2 can be called with explicit instantiation.
@@ -109,16 +109,8 @@ func _() {
 	related3[int, []int]()
 	related3[byte, List[byte]]()
 
-	// Alternatively, the 2nd type argument can be inferred
-	// from the first one through constraint type inference.
-	related3[int]()
-
-	// The inferred type is the core type of the Slice
-	// type parameter.
-	var _ []int = related3[int]()
-
-	// It is not the defined parameterized type List.
-	type anotherList []float32
-	var _ anotherList = related3[float32]() // valid
-	var _ anotherList = related3 /* ERROR cannot use .* \(value of type List\[float32\]\) as anotherList */ [float32, List[float32]]()
+	// The 2nd type argument cannot be inferred from the first
+	// one because there's two possible choices: []Elem and
+	// List[Elem].
+	related3[int]( /* ERROR cannot infer Slice */ )
 }
diff --git a/src/cmd/compile/internal/types2/testdata/examples/typesets.go2 b/src/cmd/compile/internal/types2/testdata/examples/typesets.go2
index e19dcf8da3..55ef02284b 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/typesets.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/typesets.go2
@@ -35,7 +35,7 @@ func _() int {
 	return deref(p)
 }
 
-func addrOfCopy[V any, P ~*V](v V) P {
+func addrOfCopy[V any, P *V](v V) P {
 	return &v
 }
 
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
index b8ba0ad4a7..01c9672745 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
@@ -4,7 +4,7 @@
 
 package p
 
-func f[F interface{~*Q}, G interface{~*R}, Q, R any](q Q, r R) {}
+func f[F interface{*Q}, G interface{*R}, Q, R any](q Q, r R) {}
 
 func _() {
 	f[*float64, *int](1, 2)
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51229.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51229.go2
new file mode 100644
index 0000000000..ef873e6ea8
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51229.go2
@@ -0,0 +1,164 @@
+// 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 p
+
+// Constraint type inference should be independent of the
+// ordering of the type parameter declarations. Try all
+// permutations in the test case below.
+// Permutations produced by https://go.dev/play/p/PHcZNGJTEBZ.
+
+func f00[S1 ~[]E1, S2 ~[]E2, E1 ~byte, E2 ~byte](S1, S2) {}
+func f01[S2 ~[]E2, S1 ~[]E1, E1 ~byte, E2 ~byte](S1, S2) {}
+func f02[E1 ~byte, S1 ~[]E1, S2 ~[]E2, E2 ~byte](S1, S2) {}
+func f03[S1 ~[]E1, E1 ~byte, S2 ~[]E2, E2 ~byte](S1, S2) {}
+func f04[S2 ~[]E2, E1 ~byte, S1 ~[]E1, E2 ~byte](S1, S2) {}
+func f05[E1 ~byte, S2 ~[]E2, S1 ~[]E1, E2 ~byte](S1, S2) {}
+func f06[E2 ~byte, S2 ~[]E2, S1 ~[]E1, E1 ~byte](S1, S2) {}
+func f07[S2 ~[]E2, E2 ~byte, S1 ~[]E1, E1 ~byte](S1, S2) {}
+func f08[S1 ~[]E1, E2 ~byte, S2 ~[]E2, E1 ~byte](S1, S2) {}
+func f09[E2 ~byte, S1 ~[]E1, S2 ~[]E2, E1 ~byte](S1, S2) {}
+func f10[S2 ~[]E2, S1 ~[]E1, E2 ~byte, E1 ~byte](S1, S2) {}
+func f11[S1 ~[]E1, S2 ~[]E2, E2 ~byte, E1 ~byte](S1, S2) {}
+func f12[S1 ~[]E1, E1 ~byte, E2 ~byte, S2 ~[]E2](S1, S2) {}
+func f13[E1 ~byte, S1 ~[]E1, E2 ~byte, S2 ~[]E2](S1, S2) {}
+func f14[E2 ~byte, S1 ~[]E1, E1 ~byte, S2 ~[]E2](S1, S2) {}
+func f15[S1 ~[]E1, E2 ~byte, E1 ~byte, S2 ~[]E2](S1, S2) {}
+func f16[E1 ~byte, E2 ~byte, S1 ~[]E1, S2 ~[]E2](S1, S2) {}
+func f17[E2 ~byte, E1 ~byte, S1 ~[]E1, S2 ~[]E2](S1, S2) {}
+func f18[E2 ~byte, E1 ~byte, S2 ~[]E2, S1 ~[]E1](S1, S2) {}
+func f19[E1 ~byte, E2 ~byte, S2 ~[]E2, S1 ~[]E1](S1, S2) {}
+func f20[S2 ~[]E2, E2 ~byte, E1 ~byte, S1 ~[]E1](S1, S2) {}
+func f21[E2 ~byte, S2 ~[]E2, E1 ~byte, S1 ~[]E1](S1, S2) {}
+func f22[E1 ~byte, S2 ~[]E2, E2 ~byte, S1 ~[]E1](S1, S2) {}
+func f23[S2 ~[]E2, E1 ~byte, E2 ~byte, S1 ~[]E1](S1, S2) {}
+
+type myByte byte
+
+func _(a []byte, b []myByte) {
+	f00(a, b)
+	f01(a, b)
+	f02(a, b)
+	f03(a, b)
+	f04(a, b)
+	f05(a, b)
+	f06(a, b)
+	f07(a, b)
+	f08(a, b)
+	f09(a, b)
+	f10(a, b)
+	f11(a, b)
+	f12(a, b)
+	f13(a, b)
+	f14(a, b)
+	f15(a, b)
+	f16(a, b)
+	f17(a, b)
+	f18(a, b)
+	f19(a, b)
+	f20(a, b)
+	f21(a, b)
+	f22(a, b)
+	f23(a, b)
+}
+
+// Constraint type inference may have to iterate.
+// Again, the order of the type parameters shouldn't matter.
+
+func g0[S ~[]E, M ~map[string]S, E any](m M) {}
+func g1[M ~map[string]S, S ~[]E, E any](m M) {}
+func g2[E any, S ~[]E, M ~map[string]S](m M) {}
+func g3[S ~[]E, E any, M ~map[string]S](m M) {}
+func g4[M ~map[string]S, E any, S ~[]E](m M) {}
+func g5[E any, M ~map[string]S, S ~[]E](m M) {}
+
+func _(m map[string][]byte) {
+	g0(m)
+	g1(m)
+	g2(m)
+	g3(m)
+	g4(m)
+	g5(m)
+}
+
+// Worst-case scenario.
+// There are 10 unknown type parameters. In each iteration of
+// constraint type inference we infer one more, from right to left.
+// Each iteration looks repeatedly at all 11 type parameters,
+// requiring a total of 10*11 = 110 iterations with the current
+// implementation. Pathological case.
+
+func h[K any, J ~*K, I ~*J, H ~*I, G ~*H, F ~*G, E ~*F, D ~*E, C ~*D, B ~*C, A ~*B](x A) {}
+
+func _(x **********int) {
+	h(x)
+}
+
+// Examples with channel constraints and tilde.
+
+func ch1[P chan<- int]() (_ P)           { return } // core(P) == chan<- int   (single type, no tilde)
+func ch2[P ~chan int]()                  { return } // core(P) == ~chan<- int  (tilde)
+func ch3[P chan E, E any](E)             { return } // core(P) == chan<- E     (single type, no tilde)
+func ch4[P chan E | ~chan<- E, E any](E) { return } // core(P) == ~chan<- E    (tilde)
+func ch5[P chan int | chan<- int]()      { return } // core(P) == chan<- int   (not a single type)
+
+func _() {
+	// P can be inferred as there's a single specific type and no tilde.
+	var _ chan int = ch1 /* ERROR cannot use ch1.*value of type chan<- int */ ()
+	var _ chan<- int = ch1()
+
+	// P cannot be inferred as there's a tilde.
+	ch2( /* ERROR cannot infer P */ )
+	type myChan chan int
+	ch2[myChan]()
+
+	// P can be inferred as there's a single specific type and no tilde.
+	var e int
+	ch3(e)
+
+	// P cannot be inferred as there's more than one specific type and a tilde.
+	ch4( /* ERROR cannot infer P */ e)
+	_ = ch4[chan int]
+
+	// P cannot be inferred as there's more than one specific type.
+	ch5( /* ERROR cannot infer P */ )
+	ch5[chan<- int]()
+}
+
+// test case from issue
+
+func equal[M1 ~map[K1]V1, M2 ~map[K2]V2, K1, K2 ~uint32, V1, V2 ~string](m1 M1, m2 M2) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[K2(k)]; !ok || V2(v1) != v2 {
+			return false
+		}
+	}
+	return true
+}
+
+func equalFixed[K1, K2 ~uint32, V1, V2 ~string](m1 map[K1]V1, m2 map[K2]V2) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[K2(k)]; !ok || v1 != V1(v2) {
+			return false
+		}
+	}
+	return true
+}
+
+type (
+	someNumericID uint32
+	someStringID  string
+)
+
+func _() {
+	foo := map[uint32]string{10: "bar"}
+	bar := map[someNumericID]someStringID{10: "bar"}
+	equal(foo, bar)
+}
diff --git a/src/cmd/compile/internal/types2/unify.go b/src/cmd/compile/internal/types2/unify.go
index 50edce9881..03a9534c94 100644
--- a/src/cmd/compile/internal/types2/unify.go
+++ b/src/cmd/compile/internal/types2/unify.go
@@ -247,6 +247,17 @@ func (d *tparamsList) set(i int, typ Type) {
 	}
 }
 
+// unknowns returns the number of type parameters for which no type has been set yet.
+func (d *tparamsList) unknowns() int {
+	n := 0
+	for _, ti := range d.indices {
+		if ti <= 0 {
+			n++
+		}
+	}
+	return n
+}
+
 // types returns the list of inferred types (via unification) for the type parameters
 // described by d, and an index. If all types were inferred, the returned index is < 0.
 // Otherwise, it is the index of the first type parameter which couldn't be inferred;
@@ -348,8 +359,12 @@ func (u *unifier) nify(x, y Type, p *ifacePair) (result bool) {
 	// (see issue #50755 for a test case).
 	if enableCoreTypeUnification && !u.exact {
 		if isTypeParam(x) && !hasName(y) {
+			// Caution: This may not be correct in light of ~ constraints.
+			//          See issue #51376.
+			// TODO(gri) investigate!
+			//
 			// When considering the type parameter for unification
-			// we look at the adjusted core type (adjCoreType).
+			// we look at the adjusted core type (coreTerm).
 			// If the adjusted core type is a named type N; the
 			// corresponding core type is under(N). Since !u.exact
 			// and y doesn't have a name, unification will end up
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index 85452dffe6..58b59900f9 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -466,52 +466,54 @@ func TestInstanceInfo(t *testing.T) {
 			`func(float64, *byte, ...[]byte)`,
 		},
 
-		{`package s1; func f[T any, P interface{~*T}](x T) {}; func _(x string) { f(x) }`,
+		{`package s1; func f[T any, P interface{*T}](x T) {}; func _(x string) { f(x) }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func(x string)`,
 		},
-		{`package s2; func f[T any, P interface{~*T}](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s2; func f[T any, P interface{*T}](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `*int`},
 			`func(x []int)`,
 		},
-		{`package s3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s3; type C[T any] interface{chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`},
 			`func(x []int)`,
 		},
-		{`package s4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func(x []int)`,
 		},
 
-		{`package t1; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = f[string] }`,
+		{`package t1; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = f[string] }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func() string`,
 		},
-		{`package t2; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
+		{`package t2; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func() string`,
 		},
-		{`package t3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]]() []T { return nil }; func _() { _ = f[int] }`,
-			`f`,
-			[]string{`int`, `chan<- int`},
-			`func() []int`,
-		},
-		{`package t4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
+		{`package t3; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func() []int`,
 		},
+		{`package t4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = (f[int]) }`,
+			`f`,
+			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+			`func() []int`,
+		},
+
 		{`package i0; import "lib"; func _() { lib.F(42) }`,
 			`F`,
 			[]string{`int`},
 			`func(int)`,
 		},
+
 		{`package type0; type T[P interface{~int}] struct{ x P }; var _ T[int]`,
 			`T`,
 			[]string{`int`},
diff --git a/src/go/types/infer.go b/src/go/types/infer.go
index d481aaa877..429510291e 100644
--- a/src/go/types/infer.go
+++ b/src/go/types/infer.go
@@ -487,21 +487,88 @@ func (check *Checker) inferB(posn positioner, tparams []*TypeParam, targs []Type
 		}
 	}
 
-	// If a constraint has a core type, unify the corresponding type parameter with it.
-	for _, tpar := range tparams {
-		if ctype := adjCoreType(tpar); ctype != nil {
-			if !u.unify(tpar, ctype) {
-				// TODO(gri) improve error message by providing the type arguments
-				//           which we know already
-				check.errorf(posn, _InvalidTypeArg, "%s does not match %s", tpar, ctype)
-				return nil, 0
+	// Repeatedly apply constraint type inference as long as
+	// there are still unknown type arguments and progress is
+	// being made.
+	//
+	// This is an O(n^2) algorithm where n is the number of
+	// type parameters: if there is progress (and iteration
+	// continues), at least one type argument is inferred
+	// per iteration and we have a doubly nested loop.
+	// In practice this is not a problem because the number
+	// of type parameters tends to be very small (< 5 or so).
+	// (It should be possible for unification to efficiently
+	// signal newly inferred type arguments; then the loops
+	// here could handle the respective type parameters only,
+	// but that will come at a cost of extra complexity which
+	// may not be worth it.)
+	for n := u.x.unknowns(); n > 0; {
+		nn := n
+
+		for i, tpar := range tparams {
+			// If there is a core term (i.e., a core type with tilde information)
+			// unify the type parameter with the core type.
+			if core, single := coreTerm(tpar); core != nil {
+				// A type parameter can be unified with its core type in two cases.
+				tx := u.x.at(i)
+				switch {
+				case tx != nil:
+					// The corresponding type argument tx is known.
+					// In this case, if the core type has a tilde, the type argument's underlying
+					// type must match the core type, otherwise the type argument and the core type
+					// must match.
+					// If tx is an external type parameter, don't consider its underlying type
+					// (which is an interface). Core type unification will attempt to unify against
+					// core.typ.
+					// Note also that even with inexact unification we cannot leave away the under
+					// call here because it's possible that both tx and core.typ are named types,
+					// with under(tx) being a (named) basic type matching core.typ. Such cases do
+					// not match with inexact unification.
+					if core.tilde && !isTypeParam(tx) {
+						tx = under(tx)
+					}
+					if !u.unify(tx, core.typ) {
+						// TODO(gri) improve error message by providing the type arguments
+						//           which we know already
+						// Don't use term.String() as it always qualifies types, even if they
+						// are in the current package.
+						tilde := ""
+						if core.tilde {
+							tilde = "~"
+						}
+						check.errorf(posn, _InvalidTypeArg, "%s does not match %s%s", tpar, tilde, core.typ)
+						return nil, 0
+					}
+
+				case single && !core.tilde:
+					// The corresponding type argument tx is unknown and there's a single
+					// specific type and no tilde.
+					// In this case the type argument must be that single type; set it.
+					u.x.set(i, core.typ)
+
+				default:
+					// Unification is not possible and no progress was made.
+					continue
+				}
+
+				// The number of known type arguments may have changed.
+				nn = u.x.unknowns()
+				if nn == 0 {
+					break // all type arguments are known
+				}
 			}
 		}
+
+		assert(nn <= n)
+		if nn == n {
+			break // no progress
+		}
+		n = nn
 	}
 
 	// u.x.types() now contains the incoming type arguments plus any additional type
-	// arguments which were inferred from core types. The newly inferred non-
-	// nil entries may still contain references to other type parameters.
+	// arguments which were inferred from core terms. The newly inferred non-nil
+	// entries may still contain references to other type parameters.
 	// For instance, for [A any, B interface{ []C }, C interface{ *A }], if A == int
 	// was given, unification produced the type list [int, []C, *A]. We eliminate the
 	// remaining type parameters by substituting the type parameters in this type list
@@ -590,26 +657,40 @@ func (check *Checker) inferB(posn positioner, tparams []*TypeParam, targs []Type
 	return
 }
 
-// adjCoreType returns the core type of tpar unless the
-// type parameter embeds a single, possibly named type,
-// in which case it returns that single type instead.
-// (The core type is always the underlying type of that
-// single type.)
-func adjCoreType(tpar *TypeParam) Type {
-	var single *term
-	if tpar.is(func(t *term) bool {
-		if single == nil && t != nil {
-			single = t
-			return true
+// If the type parameter has a single specific type S, coreTerm returns (S, true).
+// Otherwise, if tpar has a core type T, it returns a term corresponding to that
+// core type and false. In that case, if any term of tpar has a tilde, the core
+// term has a tilde. In all other cases coreTerm returns (nil, false).
+func coreTerm(tpar *TypeParam) (*term, bool) {
+	n := 0
+	var single *term // valid if n == 1
+	var tilde bool
+	tpar.is(func(t *term) bool {
+		if t == nil {
+			assert(n == 0)
+			return false // no terms
 		}
-		return false // zero or more than one terms
-	}) {
+		n++
+		single = t
+		if t.tilde {
+			tilde = true
+		}
+		return true
+	})
+	if n == 1 {
 		if debug {
-			assert(under(single.typ) == coreType(tpar))
+			assert(debug && under(single.typ) == coreType(tpar))
 		}
-		return single.typ
+		return single, true
 	}
-	return coreType(tpar)
+	if typ := coreType(tpar); typ != nil {
+		// A core type is always an underlying type.
+		// If any term of tpar has a tilde, we don't
+		// have a precise core type and we must return
+		// a tilde as well.
+		return &term{tilde, typ}, false
+	}
+	return nil, false
 }
 
 type cycleFinder struct {
diff --git a/src/go/types/testdata/check/funcinference.go2 b/src/go/types/testdata/check/funcinference.go2
index f04b76ca1a..45d0781cd7 100644
--- a/src/go/types/testdata/check/funcinference.go2
+++ b/src/go/types/testdata/check/funcinference.go2
@@ -8,21 +8,21 @@ import "strconv"
 
 type any interface{}
 
-func f0[A any, B interface{~*C}, C interface{~*D}, D interface{~*A}](A, B, C, D) {}
+func f0[A any, B interface{*C}, C interface{*D}, D interface{*A}](A, B, C, D) {}
 func _() {
 	f := f0[string]
 	f("a", nil, nil, nil)
 	f0("a", nil, nil, nil)
 }
 
-func f1[A any, B interface{~*A}](A, B) {}
+func f1[A any, B interface{*A}](A, B) {}
 func _() {
 	f := f1[int]
 	f(int(0), new(int))
 	f1(int(0), new(int))
 }
 
-func f2[A any, B interface{~[]A}](A, B) {}
+func f2[A any, B interface{[]A}](A, B) {}
 func _() {
 	f := f2[byte]
 	f(byte(0), []byte{})
@@ -38,7 +38,7 @@ func _() {
 // 	f3(x, &x, &x)
 // }
 
-func f4[A any, B interface{~[]C}, C interface{~*A}](A, B, C) {}
+func f4[A any, B interface{[]C}, C interface{*A}](A, B, C) {}
 func _() {
 	f := f4[int]
 	var x int
@@ -46,7 +46,7 @@ func _() {
 	f4(x, []*int{}, &x)
 }
 
-func f5[A interface{~struct{b B; c C}}, B any, C interface{~*B}](x B) A { panic(0) }
+func f5[A interface{struct{b B; c C}}, B any, C interface{*B}](x B) A { panic(0) }
 func _() {
 	x := f5(1.2)
 	var _ float64 = x.b
@@ -79,7 +79,7 @@ var _ = Double(MySlice{1})
 
 type Setter[B any] interface {
 	Set(string)
-	~*B
+	*B
 }
 
 func FromStrings[T interface{}, PT Setter[T]](s []string) []T {
diff --git a/src/go/types/testdata/check/typeinference.go2 b/src/go/types/testdata/check/typeinference.go2
index 8876ccaa4e..3d3380da9c 100644
--- a/src/go/types/testdata/check/typeinference.go2
+++ b/src/go/types/testdata/check/typeinference.go2
@@ -14,7 +14,7 @@ func _() {
 }
 
 // recursive inference
-type Tr[A any, B ~*C, C ~*D, D ~*A] int
+type Tr[A any, B *C, C *D, D *A] int
 func _() {
 	var x Tr[string]
 	var y Tr[string, ***string, **string, *string]
@@ -25,11 +25,11 @@ func _() {
 }
 
 // other patterns of inference
-type To0[A any, B ~[]A] int
-type To1[A any, B ~struct{a A}] int
-type To2[A any, B ~[][]A] int
-type To3[A any, B ~[3]*A] int
-type To4[A any, B any, C ~struct{a A; b B}] int
+type To0[A any, B []A] int
+type To1[A any, B struct{a A}] int
+type To2[A any, B [][]A] int
+type To3[A any, B [3]*A] int
+type To4[A any, B any, C struct{a A; b B}] int
 func _() {
 	var _ To0[int]
 	var _ To1[int]
diff --git a/src/go/types/testdata/examples/inference.go2 b/src/go/types/testdata/examples/inference.go2
index 70d393b455..e59a544660 100644
--- a/src/go/types/testdata/examples/inference.go2
+++ b/src/go/types/testdata/examples/inference.go2
@@ -78,7 +78,7 @@ func _() {
 	related1(si, "foo" /* ERROR cannot use "foo" */ )
 }
 
-func related2[Elem any, Slice interface{~[]Elem}](e Elem, s Slice) {}
+func related2[Elem any, Slice interface{[]Elem}](e Elem, s Slice) {}
 
 func _() {
 	// related2 can be called with explicit instantiation.
@@ -109,16 +109,8 @@ func _() {
 	related3[int, []int]()
 	related3[byte, List[byte]]()
 
-	// Alternatively, the 2nd type argument can be inferred
-	// from the first one through constraint type inference.
-	related3[int]()
-
-	// The inferred type is the core type of the Slice
-	// type parameter.
-	var _ []int = related3[int]()
-
-	// It is not the defined parameterized type List.
-	type anotherList []float32
-	var _ anotherList = related3[float32]() // valid
-	var _ anotherList = related3 /* ERROR cannot use .* \(value of type List\[float32\]\) as anotherList */ [float32, List[float32]]()
+	// The 2nd type argument cannot be inferred from the first
+	// one because there's two possible choices: []Elem and
+	// List[Elem].
+	related3 /* ERROR cannot infer Slice */ [int]()
 }
diff --git a/src/go/types/testdata/examples/typesets.go2 b/src/go/types/testdata/examples/typesets.go2
index cf01072d8c..fcddf1f1a5 100644
--- a/src/go/types/testdata/examples/typesets.go2
+++ b/src/go/types/testdata/examples/typesets.go2
@@ -35,7 +35,7 @@ func _() int {
 	return deref(p)
 }
 
-func addrOfCopy[V any, P ~*V](v V) P {
+func addrOfCopy[V any, P *V](v V) P {
 	return &v
 }
 
diff --git a/src/go/types/testdata/fixedbugs/issue45548.go2 b/src/go/types/testdata/fixedbugs/issue45548.go2
index b8ba0ad4a7..01c9672745 100644
--- a/src/go/types/testdata/fixedbugs/issue45548.go2
+++ b/src/go/types/testdata/fixedbugs/issue45548.go2
@@ -4,7 +4,7 @@
 
 package p
 
-func f[F interface{~*Q}, G interface{~*R}, Q, R any](q Q, r R) {}
+func f[F interface{*Q}, G interface{*R}, Q, R any](q Q, r R) {}
 
 func _() {
 	f[*float64, *int](1, 2)
diff --git a/src/go/types/testdata/fixedbugs/issue51229.go2 b/src/go/types/testdata/fixedbugs/issue51229.go2
new file mode 100644
index 0000000000..808b6471f6
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue51229.go2
@@ -0,0 +1,164 @@
+// 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 p
+
+// Constraint type inference should be independent of the
+// ordering of the type parameter declarations. Try all
+// permutations in the test case below.
+// Permutations produced by https://go.dev/play/p/PHcZNGJTEBZ.
+
+func f00[S1 ~[]E1, S2 ~[]E2, E1 ~byte, E2 ~byte](S1, S2) {}
+func f01[S2 ~[]E2, S1 ~[]E1, E1 ~byte, E2 ~byte](S1, S2) {}
+func f02[E1 ~byte, S1 ~[]E1, S2 ~[]E2, E2 ~byte](S1, S2) {}
+func f03[S1 ~[]E1, E1 ~byte, S2 ~[]E2, E2 ~byte](S1, S2) {}
+func f04[S2 ~[]E2, E1 ~byte, S1 ~[]E1, E2 ~byte](S1, S2) {}
+func f05[E1 ~byte, S2 ~[]E2, S1 ~[]E1, E2 ~byte](S1, S2) {}
+func f06[E2 ~byte, S2 ~[]E2, S1 ~[]E1, E1 ~byte](S1, S2) {}
+func f07[S2 ~[]E2, E2 ~byte, S1 ~[]E1, E1 ~byte](S1, S2) {}
+func f08[S1 ~[]E1, E2 ~byte, S2 ~[]E2, E1 ~byte](S1, S2) {}
+func f09[E2 ~byte, S1 ~[]E1, S2 ~[]E2, E1 ~byte](S1, S2) {}
+func f10[S2 ~[]E2, S1 ~[]E1, E2 ~byte, E1 ~byte](S1, S2) {}
+func f11[S1 ~[]E1, S2 ~[]E2, E2 ~byte, E1 ~byte](S1, S2) {}
+func f12[S1 ~[]E1, E1 ~byte, E2 ~byte, S2 ~[]E2](S1, S2) {}
+func f13[E1 ~byte, S1 ~[]E1, E2 ~byte, S2 ~[]E2](S1, S2) {}
+func f14[E2 ~byte, S1 ~[]E1, E1 ~byte, S2 ~[]E2](S1, S2) {}
+func f15[S1 ~[]E1, E2 ~byte, E1 ~byte, S2 ~[]E2](S1, S2) {}
+func f16[E1 ~byte, E2 ~byte, S1 ~[]E1, S2 ~[]E2](S1, S2) {}
+func f17[E2 ~byte, E1 ~byte, S1 ~[]E1, S2 ~[]E2](S1, S2) {}
+func f18[E2 ~byte, E1 ~byte, S2 ~[]E2, S1 ~[]E1](S1, S2) {}
+func f19[E1 ~byte, E2 ~byte, S2 ~[]E2, S1 ~[]E1](S1, S2) {}
+func f20[S2 ~[]E2, E2 ~byte, E1 ~byte, S1 ~[]E1](S1, S2) {}
+func f21[E2 ~byte, S2 ~[]E2, E1 ~byte, S1 ~[]E1](S1, S2) {}
+func f22[E1 ~byte, S2 ~[]E2, E2 ~byte, S1 ~[]E1](S1, S2) {}
+func f23[S2 ~[]E2, E1 ~byte, E2 ~byte, S1 ~[]E1](S1, S2) {}
+
+type myByte byte
+
+func _(a []byte, b []myByte) {
+	f00(a, b)
+	f01(a, b)
+	f02(a, b)
+	f03(a, b)
+	f04(a, b)
+	f05(a, b)
+	f06(a, b)
+	f07(a, b)
+	f08(a, b)
+	f09(a, b)
+	f10(a, b)
+	f11(a, b)
+	f12(a, b)
+	f13(a, b)
+	f14(a, b)
+	f15(a, b)
+	f16(a, b)
+	f17(a, b)
+	f18(a, b)
+	f19(a, b)
+	f20(a, b)
+	f21(a, b)
+	f22(a, b)
+	f23(a, b)
+}
+
+// Constraint type inference may have to iterate.
+// Again, the order of the type parameters shouldn't matter.
+
+func g0[S ~[]E, M ~map[string]S, E any](m M) {}
+func g1[M ~map[string]S, S ~[]E, E any](m M) {}
+func g2[E any, S ~[]E, M ~map[string]S](m M) {}
+func g3[S ~[]E, E any, M ~map[string]S](m M) {}
+func g4[M ~map[string]S, E any, S ~[]E](m M) {}
+func g5[E any, M ~map[string]S, S ~[]E](m M) {}
+
+func _(m map[string][]byte) {
+	g0(m)
+	g1(m)
+	g2(m)
+	g3(m)
+	g4(m)
+	g5(m)
+}
+
+// Worst-case scenario.
+// There are 10 unknown type parameters. In each iteration of
+// constraint type inference we infer one more, from right to left.
+// Each iteration looks repeatedly at all 11 type parameters,
+// requiring a total of 10*11 = 110 iterations with the current
+// implementation. Pathological case.
+
+func h[K any, J ~*K, I ~*J, H ~*I, G ~*H, F ~*G, E ~*F, D ~*E, C ~*D, B ~*C, A ~*B](x A) {}
+
+func _(x **********int) {
+	h(x)
+}
+
+// Examples with channel constraints and tilde.
+
+func ch1[P chan<- int]() (_ P)           { return } // core(P) == chan<- int   (single type, no tilde)
+func ch2[P ~chan int]()                  { return } // core(P) == ~chan<- int  (tilde)
+func ch3[P chan E, E any](E)             { return } // core(P) == chan<- E     (single type, no tilde)
+func ch4[P chan E | ~chan<- E, E any](E) { return } // core(P) == ~chan<- E    (tilde)
+func ch5[P chan int | chan<- int]()      { return } // core(P) == chan<- int   (not a single type)
+
+func _() {
+	// P can be inferred as there's a single specific type and no tilde.
+	var _ chan int = ch1 /* ERROR cannot use ch1.*value of type chan<- int */ ()
+	var _ chan<- int = ch1()
+
+	// P cannot be inferred as there's a tilde.
+	ch2 /* ERROR cannot infer P */ ()
+	type myChan chan int
+	ch2[myChan]()
+
+	// P can be inferred as there's a single specific type and no tilde.
+	var e int
+	ch3(e)
+
+	// P cannot be inferred as there's more than one specific type and a tilde.
+	ch4 /* ERROR cannot infer P */ (e)
+	_ = ch4[chan int]
+
+	// P cannot be inferred as there's more than one specific type.
+	ch5 /* ERROR cannot infer P */ ()
+	ch5[chan<- int]()
+}
+
+// test case from issue
+
+func equal[M1 ~map[K1]V1, M2 ~map[K2]V2, K1, K2 ~uint32, V1, V2 ~string](m1 M1, m2 M2) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[K2(k)]; !ok || V2(v1) != v2 {
+			return false
+		}
+	}
+	return true
+}
+
+func equalFixed[K1, K2 ~uint32, V1, V2 ~string](m1 map[K1]V1, m2 map[K2]V2) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[K2(k)]; !ok || v1 != V1(v2) {
+			return false
+		}
+	}
+	return true
+}
+
+type (
+	someNumericID uint32
+	someStringID  string
+)
+
+func _() {
+	foo := map[uint32]string{10: "bar"}
+	bar := map[someNumericID]someStringID{10: "bar"}
+	equal(foo, bar)
+}
diff --git a/src/go/types/unify.go b/src/go/types/unify.go
index ac904d6d6b..e8d355ed31 100644
--- a/src/go/types/unify.go
+++ b/src/go/types/unify.go
@@ -247,6 +247,17 @@ func (d *tparamsList) set(i int, typ Type) {
 	}
 }
 
+// unknowns returns the number of type parameters for which no type has been set yet.
+func (d *tparamsList) unknowns() int {
+	n := 0
+	for _, ti := range d.indices {
+		if ti <= 0 {
+			n++
+		}
+	}
+	return n
+}
+
 // types returns the list of inferred types (via unification) for the type parameters
 // described by d, and an index. If all types were inferred, the returned index is < 0.
 // Otherwise, it is the index of the first type parameter which couldn't be inferred;
@@ -348,8 +359,12 @@ func (u *unifier) nify(x, y Type, p *ifacePair) (result bool) {
 	// (see issue #50755 for a test case).
 	if enableCoreTypeUnification && !u.exact {
 		if isTypeParam(x) && !hasName(y) {
+			// Caution: This may not be correct in light of ~ constraints.
+			//          See issue #51376.
+			// TODO(gri) investigate!
+			//
 			// When considering the type parameter for unification
-			// we look at the adjusted core type (adjCoreType).
+			// we look at the adjusted core type (coreTerm).
 			// If the adjusted core type is a named type N; the
 			// corresponding core type is under(N). Since !u.exact
 			// and y doesn't have a name, unification will end up
diff --git a/test/typeparam/issue48424.go b/test/typeparam/issue48424.go
index b1238df697..c5e5d4b105 100644
--- a/test/typeparam/issue48424.go
+++ b/test/typeparam/issue48424.go
@@ -13,14 +13,14 @@ func identity[T int](x T) T {
 	return x
 }
 
-func min[T int|string](x, y T) T {
+func min[T int | string](x, y T) T {
 	if x < y {
 		return x
 	}
 	return y
 }
 
-func max[T ~float64](x, y T) T {
+func max[T ~int | ~float64](x, y T) T {
 	if x > y {
 		return x
 	}
@@ -48,7 +48,7 @@ func main() {
 // Some random type parameter lists with elided interfaces.
 
 type (
-	_ [T struct{}] struct{}
-	_ [M map[K]V, K comparable, V any] struct{}
-	_ [_ interface{}|int] struct{}
+	_[T struct{}]                     struct{}
+	_[M map[K]V, K comparable, V any] struct{}
+	_[_ interface{} | int]            struct{}
 )
diff --git a/test/typeparam/settable.go b/test/typeparam/settable.go
index 1f7eba3558..56cf36745b 100644
--- a/test/typeparam/settable.go
+++ b/test/typeparam/settable.go
@@ -15,7 +15,7 @@ import (
 
 type Setter[B any] interface {
 	Set(string)
-	~*B
+	*B
 }
 
 // Takes two type parameters where PT = *T
diff --git a/test/typeparam/typelist.go b/test/typeparam/typelist.go
index 27e1b60ab0..7c713212b0 100644
--- a/test/typeparam/typelist.go
+++ b/test/typeparam/typelist.go
@@ -89,7 +89,7 @@ func f1x() {
 }
 */
 
-func f2[A any, B interface{ ~[]A }](_ A, _ B) {}
+func f2[A any, B interface{ []A }](_ A, _ B) {}
 func f2x() {
 	f := f2[byte]
 	f(byte(0), []byte{})
@@ -109,7 +109,7 @@ func f3x() {
 }
 */
 
-func f4[A any, B interface{ ~[]C }, C interface{ ~*A }](_ A, _ B, c C) {}
+func f4[A any, B interface{ []C }, C interface{ *A }](_ A, _ B, c C) {}
 func f4x() {
 	f := f4[int]
 	var x int
@@ -118,11 +118,11 @@ func f4x() {
 }
 
 func f5[A interface {
-	~struct {
+	struct {
 		b B
 		c C
 	}
-}, B any, C interface{ ~*B }](x B) A {
+}, B any, C interface{ *B }](x B) A {
 	panic(0)
 }
 func f5x() {