[dev.typeparams] cmd/compile/internal/types2: parameterized functions must have a body

Add the respective check and add missing bodies to tests.
Use {} as body for functions that don't return a result.
Use { panic(0) } as body for functions that return a result.

For #47069.

Change-Id: Ia5d7525c9c036baf8a955d13bff448401e08235e
Reviewed-on: https://go-review.googlesource.com/c/go/+/340911
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

3 files changed, 14 insertions, 14 deletions

diff --git a/test/typeparam/smoketest.go b/test/typeparam/smoketest.go
index eeda25964f..5243dc5c3c 100644
--- a/test/typeparam/smoketest.go
+++ b/test/typeparam/smoketest.go
@@ -9,9 +9,9 @@
 package smoketest
 
 // type parameters for functions
-func f1[P any]()
-func f2[P1, P2 any, P3 any]()
-func f3[P interface{}](x P, y T1[int])
+func f1[P any]() {}
+func f2[P1, P2 any, P3 any]() {}
+func f3[P interface{}](x P, y T1[int]) {}
 
 // function instantiations
 var _ = f1[int]
diff --git a/test/typeparam/tparam1.go b/test/typeparam/tparam1.go
index a196caf976..698877a6f0 100644
--- a/test/typeparam/tparam1.go
+++ b/test/typeparam/tparam1.go
@@ -24,17 +24,17 @@ type (
 	_[T1, T2 any, T3 any] struct{}
 )
 
-func _[T any]()
-func _[T, T any]() // ERROR "T redeclared"
-func _[T1, T2 any](x T1) T2
+func _[T any]() {}
+func _[T, T any]() {} // ERROR "T redeclared"
+func _[T1, T2 any](x T1) T2 { panic(0) }
 
 // Type parameters are visible from opening [ to end of function.
 type C interface{}
 
-func _[T interface{}]()
-func _[T C]()
-func _[T struct{}]() // ERROR "not an interface"
-func _[T interface{ m() T }]()
+func _[T interface{}]() {}
+func _[T C]() {}
+func _[T struct{}]() {}// ERROR "not an interface"
+func _[T interface{ m() T }]() {}
 func _[T1 interface{ m() T2 }, T2 interface{ m() T1 }]() {
 	var _ T1
 }
diff --git a/test/typeparam/typelist.go b/test/typeparam/typelist.go
index a68ae1b5cd..5ba14261ab 100644
--- a/test/typeparam/typelist.go
+++ b/test/typeparam/typelist.go
@@ -85,7 +85,7 @@ func f1x() {
 }
 */
 
-func f2[A any, B interface{ type []A }](_ A, _ B)
+func f2[A any, B interface{ type []A }](_ A, _ B) {}
 func f2x() {
 	f := f2[byte]
 	f(byte(0), []byte{})
@@ -105,7 +105,7 @@ func f3x() {
 }
 */
 
-func f4[A any, B interface{ type []C }, C interface{ type *A }](_ A, _ B, c C)
+func f4[A any, B interface{ type []C }, C interface{ type *A }](_ A, _ B, c C) {}
 func f4x() {
 	f := f4[int]
 	var x int
@@ -118,14 +118,14 @@ func f5[A interface {
 		b B
 		c C
 	}
-}, B any, C interface{ type *B }](x B) A
+}, B any, C interface{ type *B }](x B) A { panic(0) }
 func f5x() {
 	x := f5(1.2)
 	var _ float64 = x.b
 	var _ float64 = *x.c
 }
 
-func f6[A any, B interface{ type struct{ f []A } }](B) A
+func f6[A any, B interface{ type struct{ f []A } }](B) A { panic(0) }
 func f6x() {
 	x := f6(struct{ f []string }{})
 	var _ string = x