Fix go mod vendor

The actual fix is relatively simple (we moved the shared libraries to
/deps and made /deps a go package). To prevent accidental breakage in
the future I also added a test.

deps/deps.go

@@ -0,0 +1,13 @@
+// Package deps exists because shared libraries must be in the same directory
+// as a go package for `go mod vendor` to work.
+// (c.f. https://github.com/golang/go/issues/26366#issuecomment-405683150)
+package deps
+
+/*
+#cgo LDFLAGS: -L${SRCDIR}
+#cgo darwin,arm64 LDFLAGS: -lautomerge_core_darwin_arm64
+#cgo darwin,amd64 LDFLAGS: -lautomerge_core_darwin_amd64
+#cgo linux,arm64 LDFLAGS: -lautomerge_core_linux_arm64 -lm
+#cgo linux,amd64 LDFLAGS: -lautomerge_core_linux_amd64 -lm
+*/
+import "C"

deps/rebuild.sh

@@ -30,15 +30,11 @@ elif [[ "$1" != "" ]]; then
 fi
 
 mkdir -p "$deps/build"
-mkdir -p "$deps/darwin_arm64"
-mkdir -p "$deps/darwin_amd64"
-mkdir -p "$deps/linux_arm64"
-mkdir -p "$deps/linux_amd64"
 
 cmake -B "$deps/build" -S "$automerge_c"
 cmake --build "$deps/build"
 cp "$deps/build/include/automerge-c/automerge.h" "$deps/.."
-cp "$deps/build/Cargo/target/aarch64-apple-darwin/release/libautomerge_core.a" "$deps/darwin_arm64"
+cp "$deps/build/Cargo/target/aarch64-apple-darwin/release/libautomerge_core.a" "$deps/libautomerge_core_darwin_arm64.a"
 
 if [[ "$1" == "local" ]]; then
     exit
@@ -53,10 +49,9 @@ function build() {
 
     RUSTFLAGS="-C panic=abort" cross +nightly build --release --manifest-path="$automerge_c/Cargo.toml" -Z build-std=std,panic_abort --target "$target" --target-dir "$deps/build"
 
-    mkdir -p "$deps/$output"
     cp "$deps/build/$target/release/libautomerge_core.a" "$deps/$output"
 }
 
-build x86_64-apple-darwin darwin_amd64
-build aarch64-unknown-linux-gnu linux_arm64
-build x86_64-unknown-linux-gnu linux_amd64
+build x86_64-apple-darwin libautomerge_core_darwin_amd64.a
+build aarch64-unknown-linux-gnu libautomerge_core_linux_arm64.a
+build x86_64-unknown-linux-gnu libautomerge_core_linux_amd64.a

deps/test_all.sh

@@ -4,7 +4,7 @@ set -e
 set -x
 
 cd "$(dirname "$(go env GOMOD)")"
-GOOS=darwin GOARCH=arm64 go test
+GOOS=darwin GOARCH=arm64 go test ./...
 CGO_ENABLED=1 GOOS=darwin GOARCH=amd64 go test
 docker run --platform linux/arm64 -v "$(realpath):/automerge" -it --workdir /automerge golang go test
 docker run --platform linux/amd64 -v "$(realpath):/automerge" -it --workdir /automerge golang go test

deps/vendor_test.go

@@ -0,0 +1,23 @@
+package deps
+
+import "os"
+import "os/exec"
+import "testing"
+
+func TestVendored(t *testing.T) {
+	os.Chdir("vendor_test")
+
+	run := func(c string, args ...string) {
+		cmd := exec.Command(c, args...)
+		output, err := cmd.CombinedOutput()
+		if err != nil {
+			os.Stdout.Write(output)
+			t.Fatal(err)
+		}
+	}
+
+	run("go", "mod", "tidy")
+	run("go", "mod", "vendor")
+	run("go", "test")
+	run("git", "checkout", "go.mod")
+}

deps/vendor_test/.gitignore

@@ -0,0 +1,2 @@
+vendor/
+go.sum

deps/vendor_test/go.mod

@@ -0,0 +1,6 @@
+go 1.19
+
+module github.com/automerge/vendor-test
+
+require github.com/automerge/automerge-go v0.0.0
+replace github.com/automerge/automerge-go => ../../

deps/vendor_test/main_test.go

@@ -0,0 +1,8 @@
+package main
+
+import "github.com/automerge/automerge-go"
+import "testing"
+
+func TestWorking(t *testing.T) {
+	automerge.New()
+}

result.go

@@ -1,18 +1,14 @@
 package automerge
 
 /*
-#cgo LDFLAGS: -lautomerge_core
-#cgo darwin,arm64 LDFLAGS: -L${SRCDIR}/deps/darwin_arm64
-#cgo darwin,amd64 LDFLAGS: -L${SRCDIR}/deps/darwin_amd64
-#cgo linux,arm64 LDFLAGS: -L${SRCDIR}/deps/linux_arm64 -lm
-#cgo linux,amd64 LDFLAGS: -L${SRCDIR}/deps/linux_amd64 -lm
-
 #include "automerge.h"
 */
 import "C"
 import (
 	"fmt"
 	"runtime"
+
+	_ "github.com/automerge/automerge-go/deps"
 )
 
 // result wraps an AMresult, and arranges for it to be AMfree'd after