cmd/compile: don't inline fn with shape params, but passed no shape arg

This is the same fix as CL 36126, but for the reverse case, function
with shape params but passed no shape arg. The same conversion problem
may occur in this case, see details explanation there.

Fixes #51909
Fixes #51925

Change-Id: Ib0c1973c7511d85b4918a252c80060f1864180cf
Reviewed-on: https://go-review.googlesource.com/c/go/+/395854
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/compile/internal/inline/inl.go

@@ -701,7 +701,7 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 	// apparent when we first created the instantiation of the generic function.
 	// We can't handle this if we actually do the inlining, since we want to know
 	// all interface conversions immediately after stenciling. So, we avoid
-	// inlining in this case. See #49309.
+	// inlining in this case. See #49309. (1)
 	if !fn.Type().HasShape() {
 		for _, arg := range n.Args {
 			if arg.Type().HasShape() {
@@ -712,6 +712,23 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 				return n
 			}
 		}
+	} else {
+		// Don't inline a function fn that has shape parameters, but is passed no shape arg.
+		// See comments (1) above, and issue #51909
+		inlineable := false
+		for _, arg := range n.Args {
+			if arg.Type().HasShape() {
+				inlineable = true
+				break
+			}
+		}
+		if !inlineable {
+			if logopt.Enabled() {
+				logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(ir.CurFunc),
+					fmt.Sprintf("inlining shape function %v with no shape args", ir.FuncName(fn)))
+			}
+			return n
+		}
 	}
 
 	if base.Flag.Cfg.Instrumenting && types.IsRuntimePkg(fn.Sym().Pkg) {

test/typeparam/issue51909.go

@@ -0,0 +1,30 @@
+// compile
+
+// 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
+
+type None struct{}
+
+type Response interface {
+	send(ctx *struct{})
+}
+
+type HandlerFunc[Input any] func(Input) Response
+
+func Operation[Input any](method, path string, h HandlerFunc[Input]) {
+	var input Input
+	h(input)
+}
+
+func Get[Body any](path string, h HandlerFunc[struct{ Body Body }]) {
+	Operation("GET", path, h)
+}
+
+func main() {
+	Get("/", func(req struct{ Body None }) Response {
+		return nil
+	})
+}

test/typeparam/issue51925.go

@@ -0,0 +1,52 @@
+// compile
+
+// 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 "fmt"
+
+type IntLike interface {
+	~int | ~int64 | ~int32 | ~int16 | ~int8
+}
+
+func Reduce[T any, U any, Uslice ~[]U](function func(T, U) T, sequence Uslice, initial T) T {
+	result := initial
+	for _, x := range sequence {
+		result = function(result, x)
+	}
+	return result
+}
+
+func min[T IntLike](x, y T) T {
+	if x < y {
+		return x
+	}
+	return y
+
+}
+
+// Min returns the minimum element of `nums`.
+func Min[T IntLike, NumSlice ~[]T](nums NumSlice) T {
+	if len(nums) == 0 {
+		return T(0)
+	}
+	return Reduce(min[T], nums, nums[0])
+}
+
+// VarMin is the variadic version of Min.
+func VarMin[T IntLike](nums ...T) T {
+	return Min(nums)
+}
+
+type myInt int
+
+func main() {
+	fmt.Println(VarMin(myInt(1), myInt(2)))
+
+	seq := []myInt{1, 2}
+	fmt.Println(Min(seq))
+	fmt.Println(VarMin(seq...))
+}