Keep go generated code from causing a collision

Example:

```
   interface Persistent {
   }

   annotation persistent(interface, field) :Void;
```

The annotation `persistent` generates the following go code
(before this change):

   `const Persistent = uint64(0x...)`

After this change, the generated code for an annotation always appends
an underscore:

   `const Persistent_ = uint64(0x...)`

Discussed on capnproto#46,
capnproto/capnproto#323, as well as
a $Go.name() to rename the annotation in this repo, which is
essentially maintaining a fork of upstream capnp's persistent.capnp.

This removes the $Go.name(), as a small step toward removing
go-capnp's copies of capnp files.

capnpc-go/capnpc-go.go

@@ -1,4 +1,7 @@
 /*
+Copyright (c) 2013-2023 Sandstorm Development Group, Inc. and contributors
+Licensed under the MIT License:
+
 capnpc-go is the Cap'n proto code generator for Go.  It reads a
 CodeGeneratorRequest from stdin and for a file foo.capnp it writes
 foo.capnp.go.  This is usually invoked from `capnp compile -ogo`.

capnpc-go/capnpc-go_test.go

@@ -1,3 +1,7 @@
+/*
+Copyright (c) 2013-2023 Sandstorm Development Group, Inc. and contributors
+Licensed under the MIT License:
+*/
 package main
 
 import (
@@ -537,7 +541,7 @@ func TestPersistent(t *testing.T) {
 			break;
 		}
 		defer os.RemoveAll(dir)
-		genfname := filepath.Join(dir, test.fname+".go")
+		genfname := test.fname+".go"
 
 		data, err := readTestFile(test.fname)
 		if err != nil {
@@ -554,36 +558,39 @@ func TestPersistent(t *testing.T) {
 			t.Errorf("Reading code generator request %q: %v", test.fname, err)
 			continue
 		}
-		requestedFiles, err := req.RequestedFiles()
+		reqFiles, err := req.RequestedFiles()
 		if err != nil {
 			t.Errorf("Reading code generator request %q: RequestedFiles: %v", test.fname, err)
 			continue
 		}
-		if requestedFiles.Len() < 1 {
-			t.Errorf("Reading code generator request %q: %d RequestedFiles", test.fname, requestedFiles.Len())
+		if reqFiles.Len() < 1 {
+			t.Errorf("Reading code generator request %q: %d RequestedFiles", test.fname, reqFiles.Len())
 			continue
 		}
 		nodes, err := buildNodeMap(req)
 		if err != nil {
 			t.Errorf("buildNodeMap %q: %v", test.fname, err)
 			continue
 		}
-		g := newGenerator(requestedFiles.At(0).Id(), nodes, test.opts)
-		if err := g.defineFile(); err != nil {
-			t.Errorf("defineFile %q %+v: %v", test.fname, test.opts, err)
+		g := newGenerator(reqFiles.At(0).Id(), nodes, test.opts)
+		err = g.defineFile()
+		if err != nil {
+			reqFname, _ := reqFiles.At(0).Filename()
+			t.Errorf("defineFile %q %+v: file %q: %v", test.fname, test.opts, reqFname, err)
 			continue
 		}
 		src := g.generate()
-		err = os.WriteFile(genfname, []byte(src), 0660)
+		genfpath := filepath.Join(dir, genfname)
+		err = os.WriteFile(genfpath, []byte(src), 0660)
 		if err != nil {
-			t.Fatalf("Writing generated code %q: %v", genfname, err)
+			t.Fatalf("Writing generated code %q: %v", genfpath, err)
 			break
 		}
 
-		// Relies on persistent-simple.capnp with $Go.package("") that
-		// is not "main" so `go build` skips writing an executable.
+		// Relies on persistent-simple.capnp with $Go.package("persistent_simple")
+		// not being ("main"). Thus `go build` skips writing an executable.
 		args := []string{
-			"build", "-C", dir, test.fname+".go",
+			"build", "-C", dir, genfname,
 		}
 		cmd := exec.Command("go", args...)
 		cmd.Stdin = strings.NewReader("")
@@ -594,9 +601,10 @@ func TestPersistent(t *testing.T) {
 		if err = cmd.Run(); err != nil {
 			if gotcode, ok := err.(*exec.ExitError); ok {
 				exitcode := gotcode.ExitCode()
-				t.Errorf("exitcode:%d", exitcode)
+				t.Errorf("go %+v exitcode:%d", args, exitcode)
 				t.Errorf("sout:\n%s", sout.String())
 				t.Errorf("serr:\n%s", serr.String())
+				//t.Errorf("\n%s:\n%s", genfname, src)
 				continue
 			} else {
 				t.Errorf("go %+v: %v", args, err)

capnpc-go/nodes.go

@@ -257,7 +257,13 @@ func resolveName(nodes nodeMap, n *node, base, name string, file *node) error {
 	}
 	name = parseAnnotations(na).Rename(name)
 	if base == "" {
-		n.Name = strings.Title(name)
+		if n.Which() == schema.Node_Which_annotation {
+			// Keep Annotation from colliding with another node that only
+			// differs in capitalization (see: persistent.capnp)
+			n.Name = strings.Title(name) + "_"
+		} else {
+			n.Name = strings.Title(name)
+		}
 	} else {
 		n.Name = base + "_" + name
 	}

capnpc-go/testdata/persistent-simple.capnp

@@ -1,4 +1,4 @@
-# Copyright (c) 2023
+# Copyright (c) 2023 Sandstorm Development Group, Inc. and contributors
 # Licensed under the MIT License:
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -19,17 +19,19 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-using Cxx = import "/capnp/c++.capnp";
-using Go = import "/go.capnp";
+using Go = import "go.capnp";
 
 @0xbcfe42e3392b05a8;
 
-$Cxx.namespace("test_regen");
-$Go.package("test_regen");
-$Go.import("foo/test_regen");
+$Go.package("persistent_simple");
+$Go.import("capnproto.org/go/capnp/v3/capnpc-go/testdata/persistent-simple");
 
+# defining any "interface" fails with "persistent-simple.capnp.out.go:49:33: undefined: context"
 interface Persistent {
-  call @0 () -> ();
 }
 
 annotation persistent(interface, field) :Void;
+
+struct ThisStructOnlyNeededToGetImportsToWork {
+  value @0 :Int64;
+}

std/capnp/persistent.capnp

@@ -108,7 +108,7 @@ interface Persistent@0xc8cb212fcd9f5691(SturdyRef, Owner) {
   }
 }
 
-annotation persistent(interface, field) :Void $Go.name("PersistentAnnotation");
+annotation persistent(interface, field) :Void;
 # Apply this annotation to interfaces for objects that will always be persistent, instead of
 # extending the Persistent capability, since the correct type parameters to Persistent depend on
 # the realm, which is orthogonal to the interface type and therefore should not be defined

std/fixups.patch

@@ -38,14 +38,3 @@
 
      interface @17 :Void;
      # The only interface value that can be represented statically is "null", whose methods always
---- a/capnp/persistent.capnp	2021-10-21 15:12:33.501158612 -0400
-+++ b/capnp/persistent.capnp	2021-10-21 15:13:31.930030219 -0400
-@@ -108,7 +108,7 @@
-   }
- }
-
--annotation persistent(interface, field) :Void;
-+annotation persistent(interface, field) :Void $Go.name("PersistentAnnotation");
- # Apply this annotation to interfaces for objects that will always be persistent, instead of
- # extending the Persistent capability, since the correct type parameters to Persistent depend on
- # the realm, which is orthogonal to the interface type and therefore should not be defined