cmd/compile: fix case where func-valued field of a generic type is called

Added test example orderedmap.go (binary search tree) that requires this
fix (calling function compare in _Map).

Also added new tests slices.go and metrics.go that just work.

Change-Id: Ifa5f42ab6eee9aa54c40f0eca19e00a87f8f608a
Reviewed-on: https://go-review.googlesource.com/c/go/+/301829
Trust: Dan Scales <danscales@google.com>
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

1 files changed, 318 insertions, 0 deletions

diff --git a/test/typeparam/slices.go b/test/typeparam/slices.go
new file mode 100644
index 0000000000..149199eb64
--- /dev/null
+++ b/test/typeparam/slices.go
@@ -0,0 +1,318 @@
+// run -gcflags=-G=3
+
+// 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 slices provides functions for basic operations on
+// slices of any element type.
+package main
+
+import (
+	"fmt"
+	"math"
+	"strings"
+)
+
+type Ordered interface {
+        type int, int8, int16, int32, int64,
+                uint, uint8, uint16, uint32, uint64, uintptr,
+                float32, float64,
+                string
+}
+
+type Integer interface {
+        type int, int8, int16, int32, int64,
+                uint, uint8, uint16, uint32, uint64, uintptr
+}
+
+// Max returns the maximum of two values of some ordered type.
+func _Max[T Ordered](a, b T) T {
+        if a > b {
+                return a
+        }
+        return b
+}
+
+// Min returns the minimum of two values of some ordered type.
+func _Min[T Ordered](a, b T) T {
+        if a < b {
+                return a
+        }
+        return b
+}
+
+// _Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func _Equal[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// _EqualFn reports whether two slices are equal using a comparision
+// function on each element.
+func _EqualFn[Elem any](s1, s2 []Elem, eq func(Elem, Elem) bool) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if !eq(v1, v2) {
+			return false
+		}
+	}
+	return true
+}
+
+// _Map turns a []Elem1 to a []Elem2 using a mapping function.
+func _Map[Elem1, Elem2 any](s []Elem1, f func(Elem1) Elem2) []Elem2 {
+	r := make([]Elem2, len(s))
+	for i, v := range s {
+		r[i] = f(v)
+	}
+	return r
+}
+
+// _Reduce reduces a []Elem1 to a single value of type Elem2 using
+// a reduction function.
+func _Reduce[Elem1, Elem2 any](s []Elem1, initializer Elem2, f func(Elem2, Elem1) Elem2) Elem2 {
+	r := initializer
+	for _, v := range s {
+		r = f(r, v)
+	}
+	return r
+}
+
+// _Filter filters values from a slice using a filter function.
+func _Filter[Elem any](s []Elem, f func(Elem) bool) []Elem {
+	var r []Elem
+	for _, v := range s {
+		if f(v) {
+			r = append(r, v)
+		}
+	}
+	return r
+}
+
+// _Max returns the maximum element in a slice of some ordered type.
+// If the slice is empty it returns the zero value of the element type.
+func _SliceMax[Elem Ordered](s []Elem) Elem {
+	if len(s) == 0 {
+		var zero Elem
+		return zero
+	}
+	return _Reduce(s[1:], s[0], _Max[Elem])
+}
+
+// _Min returns the minimum element in a slice of some ordered type.
+// If the slice is empty it returns the zero value of the element type.
+func _SliceMin[Elem Ordered](s []Elem) Elem {
+	if len(s) == 0 {
+		var zero Elem
+		return zero
+	}
+	return _Reduce(s[1:], s[0], _Min[Elem])
+}
+
+// _Append adds values to the end of a slice, returning a new slice.
+// This is like the predeclared append function; it's an example
+// of how to write it using generics. We used to write code like
+// this before append was added to the language, but we had to write
+// a separate copy for each type.
+func _Append[T any](s []T, t ...T) []T {
+	lens := len(s)
+	tot := lens + len(t)
+	if tot <= cap(s) {
+		s = s[:tot]
+	} else {
+		news := make([]T, tot, tot + tot/2)
+		_Copy(news, s)
+		s = news
+	}
+	_Copy(s[lens:tot], t)
+	return s
+}
+
+// _Copy copies values from t to s, stopping when either slice is full,
+// returning the number of values copied. This is like the predeclared
+// copy function; it's an example of how to write it using generics.
+func _Copy[T any](s, t []T) int {
+	i := 0
+	for ; i < len(s) && i < len(t); i++ {
+		s[i] = t[i]
+	}
+	return i
+}
+
+func TestEqual() {
+        s1 := []int{1, 2, 3}
+        if !_Equal(s1, s1) {
+                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s1))
+        }
+        s2 := []int{1, 2, 3}
+        if !_Equal(s1, s2) {
+                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
+        }
+        s2 = append(s2, 4)
+        if _Equal(s1, s2) {
+                panic(fmt.Sprintf("_Equal(%v, %v) = true, want false", s1, s2))
+        }
+
+        s3 := []float64{1, 2, math.NaN()}
+        if !_Equal(s3, s3) {
+                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s3, s3))
+        }
+
+        if _Equal(s1, nil) {
+                panic(fmt.Sprintf("_Equal(%v, nil) = true, want false", s1))
+        }
+        if _Equal(nil, s1) {
+                panic(fmt.Sprintf("_Equal(nil, %v) = true, want false", s1))
+        }
+        if !_Equal(s1[:0], nil) {
+                panic(fmt.Sprintf("_Equal(%v, nil = false, want true", s1[:0]))
+        }
+}
+
+func offByOne[Elem Integer](a, b Elem) bool {
+	return a == b + 1 || a == b - 1
+}
+
+func TestEqualFn() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{2, 3, 4}
+	if _EqualFn(s1, s1, offByOne[int]) {
+		panic(fmt.Sprintf("_EqualFn(%v, %v, offByOne) = true, want false", s1, s1))
+	}
+	if !_EqualFn(s1, s2, offByOne[int]) {
+		panic(fmt.Sprintf("_EqualFn(%v, %v, offByOne) = false, want true", s1, s2))
+	}
+
+	if !_EqualFn(s1[:0], nil, offByOne[int]) {
+		panic(fmt.Sprintf("_EqualFn(%v, nil, offByOne) = false, want true", s1[:0]))
+	}
+
+	s3 := []string{"a", "b", "c"}
+	s4 := []string{"A", "B", "C"}
+	if !_EqualFn(s3, s4, strings.EqualFold) {
+		panic(fmt.Sprintf("_EqualFn(%v, %v, strings.EqualFold) = false, want true", s3, s4))
+	}
+}
+
+func TestMap() {
+	s1 := []int{1, 2, 3}
+	s2 := _Map(s1, func(i int) float64 { return float64(i) * 2.5 })
+	if want := []float64{2.5, 5, 7.5}; !_Equal(s2, want) {
+		panic(fmt.Sprintf("_Map(%v, ...) = %v, want %v", s1, s2, want))
+	}
+
+	s3 := []string{"Hello", "World"}
+	s4 := _Map(s3, strings.ToLower)
+	if want := []string{"hello", "world"}; !_Equal(s4, want) {
+		panic(fmt.Sprintf("_Map(%v, strings.ToLower) = %v, want %v", s3, s4, want))
+	}
+
+	s5 := _Map(nil, func(i int) int { return i })
+	if len(s5) != 0 {
+		panic(fmt.Sprintf("_Map(nil, identity) = %v, want empty slice", s5))
+	}
+}
+
+func TestReduce() {
+	s1 := []int{1, 2, 3}
+	r := _Reduce(s1, 0, func(f float64, i int) float64 { return float64(i) * 2.5 + f })
+	if want := 15.0; r != want {
+		panic(fmt.Sprintf("_Reduce(%v, 0, ...) = %v, want %v", s1, r, want))
+	}
+
+	if got := _Reduce(nil, 0, func(i, j int) int { return i + j}); got != 0 {
+		panic(fmt.Sprintf("_Reduce(nil, 0, add) = %v, want 0", got))
+	}
+}
+
+func TestFilter() {
+	s1 := []int{1, 2, 3}
+	s2 := _Filter(s1, func(i int) bool { return i%2 == 0 })
+	if want := []int{2}; !_Equal(s2, want) {
+		panic(fmt.Sprintf("_Filter(%v, even) = %v, want %v", s1, s2, want))
+	}
+
+	if s3 := _Filter(s1[:0], func(i int) bool { return true }); len(s3) > 0 {
+		panic(fmt.Sprintf("_Filter(%v, identity) = %v, want empty slice", s1[:0], s3))
+	}
+}
+
+func TestMax() {
+	s1 := []int{1, 2, 3, -5}
+	if got, want := _SliceMax(s1), 3; got != want {
+		panic(fmt.Sprintf("_Max(%v) = %d, want %d", s1, got, want))
+	}
+
+	s2 := []string{"aaa", "a", "aa", "aaaa"}
+	if got, want := _SliceMax(s2), "aaaa"; got != want {
+		panic(fmt.Sprintf("_Max(%v) = %q, want %q", s2, got, want))
+	}
+
+	if got, want := _SliceMax(s2[:0]), ""; got != want {
+		panic(fmt.Sprintf("_Max(%v) = %q, want %q", s2[:0], got, want))
+	}
+}
+
+func TestMin() {
+	s1 := []int{1, 2, 3, -5}
+	if got, want := _SliceMin(s1), -5; got != want {
+		panic(fmt.Sprintf("_Min(%v) = %d, want %d", s1, got, want))
+	}
+
+	s2 := []string{"aaa", "a", "aa", "aaaa"}
+	if got, want := _SliceMin(s2), "a"; got != want {
+		panic(fmt.Sprintf("_Min(%v) = %q, want %q", s2, got, want))
+	}
+
+	if got, want := _SliceMin(s2[:0]), ""; got != want {
+		panic(fmt.Sprintf("_Min(%v) = %q, want %q", s2[:0], got, want))
+	}
+}
+
+func TestAppend() {
+	s := []int{1, 2, 3}
+	s = _Append(s, 4, 5, 6)
+	want := []int{1, 2, 3, 4, 5, 6}
+	if !_Equal(s, want) {
+		panic(fmt.Sprintf("after _Append got %v, want %v", s, want))
+	}
+}
+
+func TestCopy() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{4, 5}
+	if got := _Copy(s1, s2); got != 2 {
+		panic(fmt.Sprintf("_Copy returned %d, want 2", got))
+	}
+	want := []int{4, 5, 3}
+	if !_Equal(s1, want) {
+		panic(fmt.Sprintf("after _Copy got %v, want %v", s1, want))
+	}
+}
+func main() {
+	TestEqual()
+	TestEqualFn()
+	TestMap()
+	TestReduce()
+	TestFilter()
+	TestMax()
+	TestMin()
+	TestAppend()
+	TestCopy()
+}