Add stringintconv and ifaceassert to govet (#1360)

test/testdata/govet.go

@@ -8,7 +8,7 @@ import (
 	"os"
 )
 
-func Govet() error {
+func GovetComposites() error {
 	return &os.PathError{"first", "path", os.ErrNotExist} // ERROR "composites: \\`(os|io/fs)\\.PathError\\` composite literal uses unkeyed fields"
 }
 
@@ -36,3 +36,8 @@ func GovetPrintf() {
 	x := "dummy"
 	fmt.Printf("%d", x) // ERROR "printf: Printf format %d has arg x of wrong type string"
 }
+
+func GovetStringIntConv() {
+	i := 42
+	fmt.Println("i = " + string(i)) // ERROR "stringintconv: conversion from int to string yields a string of one rune, not a string of digits \\(did you mean fmt.Sprint\\(x\\)\\?\\)"
+}

test/testdata/govet_ifaceassert.go

@@ -0,0 +1,14 @@
+//args: -Egovet
+//config: linters-settings.govet.enable=ifaceassert
+package testdata
+
+import (
+	"io"
+)
+
+func GovetIfaceAssert() {
+	var v interface {
+		Read()
+	}
+	_ = v.(io.Reader) // ERROR "impossible type assertion: no type can implement both interface\\{Read\\(\\)\\} and io\\.Reader \\(conflicting types for Read method\\)"
+}