Allow "go mod vendor" to work correctly

This adds extra `gokeep.go` files into each directory that only contains C source code, to ensure Go's "go mod vendor" command retains the source files correctly. Previously this required use of other vendor tools like modvendor, which are now no longer required.

Author: cmgsj

Diff for: Makefile

@@ -61,6 +61,7 @@ update_source: clean $(LIBDIR)
 	# Other support files
 	rm -fr testdata
 	cp -a $(LIBDIR)/testdata testdata
+	bash scripts/gokeep.sh
 
 clean:
 	-@ $(RM) -r $(LIB_TMPDIR)

Diff for: parser/build_cgo.go

@@ -0,0 +1,54 @@
+//go:build required
+// +build required
+
+package parser
+
+// This file exists purely to prevent the Golang toolchain from stripping
+// away the C source directories and files when `go mod vendor` is used
+// to populate a `vendor/` directory of a project depending on `github.com/pganalyze/pg_query_go/v6`.
+//
+// How it works:
+//  - Every directory which only includes C source files receives a gokeep.go file.
+//  - Every directory we want to preserve is included here as a _ import.
+//  - This file is given a build tag to exclude it from the regular build.
+import (
+	// Prevent Go tooling from stripping out the C source files.
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/access"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/archive"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/catalog"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/commands"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/common"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/datatype"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/executor"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/foreign"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/jit"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/lib"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/libpq"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/mb"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/nodes"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/optimizer"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/parser"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/partitioning"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port/atomics"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port/win32"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port/win32/arpa"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port/win32/netinet"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port/win32/sys"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port/win32_msvc"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/port/win32_msvc/sys"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/portability"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/postmaster"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/regex"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/replication"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/rewrite"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/storage"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/tcop"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/tsearch"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/postgres/utils"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/protobuf"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/protobuf-c"
+	_ "github.com/pganalyze/pg_query_go/v6/parser/include/xxhash"
+)

Diff for: parser/include/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/access/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/archive/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/catalog/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/commands/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/common/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/datatype/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/executor/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/foreign/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/jit/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/lib/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/libpq/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/mb/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/nodes/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/optimizer/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/parser/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/partitioning/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/atomics/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/win32/arpa/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/win32/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/win32/netinet/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/win32/sys/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/win32_msvc/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/port/win32_msvc/sys/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/portability/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/postmaster/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/regex/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/replication/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/rewrite/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/storage/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/tcop/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/tsearch/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/postgres/utils/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/protobuf-c/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/protobuf/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: parser/include/xxhash/gokeep.go

@@ -0,0 +1,5 @@
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep

Diff for: pg_query.pb.go

@@ -0,0 +1,36 @@
+#!/bin/bash -e
+
+c_dir="parser/include"
+
+go_module="$(go list -m)"
+go_imports=""
+
+while IFS='' read -r c_dir; do
+    go_imports+="	_ \"${go_module}/${c_dir}\""$'\n'
+    cat <<EOF >"${c_dir}/gokeep.go"
+//go:build required
+// +build required
+
+// package gokeep prevents go tooling from stripping the C dependencies.
+package gokeep
+EOF
+done < <(find ${c_dir} -type f \( -name '*.c' -o -name '*.h' \) -exec dirname {} \; | sort -u)
+
+cat <<EOF >"parser/build_cgo.go"
+//go:build required
+// +build required
+
+package parser
+
+// This file exists purely to prevent the Golang toolchain from stripping
+// away the C source directories and files when \`go mod vendor\` is used
+// to populate a \`vendor/\` directory of a project depending on \`${go_module}\`.
+//
+// How it works:
+//  - Every directory which only includes C source files receives a gokeep.go file.
+//  - Every directory we want to preserve is included here as a _ import.
+//  - This file is given a build tag to exclude it from the regular build.
+import (
+	// Prevent Go tooling from stripping out the C source files.
+${go_imports})
+EOF