Currently we expose libvirt Go packages at

  libvirt.org/libvirt-go
  libvirt.org/libvirt-go-xml

These packages have not supported Go modules historically and when we
tried to introduce modules, we hit the problem that we're not using
semver for versioning.

The only way around this is to introduce new packages under a different
namespace, that will have the exact same code, but be tagged with a
different version numbering scheme.

This change proposes:

  libvirt.org/go/libvirt
  libvirt.org/go/libvirtxml

Note the hyphen is removed so that the import basename matches the
Go package name.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 docs/go/libvirt.rst     | 19 +++++++++++++++
 docs/go/libvirtxml.rst  | 16 +++++++++++++
 docs/go/meson.build     | 53 +++++++++++++++++++++++++++++++++++++++++
 docs/libvirt-go-xml.rst | 24 ++++++++++++++-----
 docs/libvirt-go.rst     | 23 ++++++++++++++----
 docs/meson.build        |  1 +
 6 files changed, 125 insertions(+), 11 deletions(-)
 create mode 100644 docs/go/libvirt.rst
 create mode 100644 docs/go/libvirtxml.rst
 create mode 100644 docs/go/meson.build

diff --git a/docs/go/libvirt.rst b/docs/go/libvirt.rst
new file mode 100644
index 0000000000..6a1344ad3e
--- /dev/null
+++ b/docs/go/libvirt.rst
@@ -0,0 +1,19 @@
+=========================================
+Libvirt Go Language API (with Go modules)
+=========================================
+
+The `Go <https://golang.org/>`__ package ``libvirt.org/go/libvirt`` provides
+`CGo <https://golang.org/cmd/cgo/>`__ binding from the OS native Libvirt API.
+
+This package replaces the obsolete `libvirt.org/libvirt-go
+<../libvirt-go.html>`__ package in order to switch to using `semver
+<https://semver.org/>`__ and `Go modules <https://golang.org/ref/mod>`__.
+Aside from the changed import path and versioning scheme, the API is fully
+compatible with the legacy package.
+
+In general the Go representation is a direct 1-1 mapping from native API
+concepts to Go, so the native API documentation should serve as a reference
+for most behaviour.
+
+For details of Go specific behaviour consult the
+`Go package documentation <https://pkg.go.dev/libvirt.org/go/libvirt>`__.
diff --git a/docs/go/libvirtxml.rst b/docs/go/libvirtxml.rst
new file mode 100644
index 0000000000..5407d609f2
--- /dev/null
+++ b/docs/go/libvirtxml.rst
@@ -0,0 +1,16 @@
+============================================
+Libvirt Go XML parsing API (with Go modules)
+============================================
+
+The `Go <https://golang.org/>`__ package ``libvirt.org/go/libvirtxml`` provides
+annotated Go struct definitions for parsing (and formatting) XML documents used
+with libvirt APIs.
+
+This package replaces the obsolete `libvirt.org/libvirt-go-xml
+<../libvirt-go-xml.html>`__ package in order to switch to using `semver
+<https://semver.org/>`__ and `Go modules <https://golang.org/ref/mod>`__.
+Aside from the changed import path and versioning scheme, the API is fully
+compatible with the original package.
+
+For details of Go specific behaviour consult the
+`Go package documentation <https://pkg.go.dev/libvirt.org/go/libvirtxml>`__.
diff --git a/docs/go/meson.build b/docs/go/meson.build
new file mode 100644
index 0000000000..d2accd322b
--- /dev/null
+++ b/docs/go/meson.build
@@ -0,0 +1,53 @@
+docs_go_files = [
+  'libvirt',
+  'libvirtxml',
+]
+
+html_xslt_gen_xslt = subsite_xsl
+html_xslt_gen_install_dir = docs_html_dir / 'go'
+html_xslt_gen = []
+
+foreach name : docs_go_files
+  rst_file = '@0@.rst'.format(name)
+
+  html_xslt_gen += {
+    'name': name,
+    'file': docs_rst2html_gen.process(rst_file),
+    'source': 'docs' / 'go' / rst_file,
+  }
+endforeach
+
+# keep the XSLT processing code block in sync with docs/meson.build
+
+# --- begin of XSLT processing ---
+
+foreach data : html_xslt_gen
+  html_filename = data['name'] + '.html'
+
+  html_file = custom_target(
+    html_filename,
+    input: data.get('file', data['name'] + '.html.in'),
+    output: html_filename,
+    command: [
+      xsltproc_prog,
+      '--stringparam', 'pagesrc', data.get('source', ''),
+      '--stringparam', 'builddir', meson.build_root(),
+      '--stringparam', 'timestamp', docs_timestamp,
+      '--nonet',
+      html_xslt_gen_xslt,
+      '@INPUT@',
+    ],
+    depends: data.get('depends', []),
+    depend_files: [ page_xsl ],
+    capture: true,
+    install: true,
+    install_dir: html_xslt_gen_install_dir,
+  )
+
+  install_web_deps += html_file
+  install_web_files += html_file.full_path() + ':' + html_xslt_gen_install_dir
+endforeach
+
+html_xslt_gen = []
+
+# --- end of XSLT processing ---
diff --git a/docs/libvirt-go-xml.rst b/docs/libvirt-go-xml.rst
index 995fdd2b07..43ebf50765 100644
--- a/docs/libvirt-go-xml.rst
+++ b/docs/libvirt-go-xml.rst
@@ -1,10 +1,22 @@
-==========================
-Libvirt Go XML parsing API
-==========================
+===================================================
+Obsolete libvirt Go XML parsing API (no Go modules)
+===================================================
 
-The `Go <https://golang.org/>`__ package ``libvirt.org/libvirt-go-xml`` provides
-annotated Go struct definitions for parsing (and formatting) XML documents used
-with libvirt APIs.
+This obsolete `Go <https://golang.org/>`__ package ``libvirt.org/libvirt-go-xml``
+provided annotated Go struct definitions for parsing (and formatting) XML
+documents used with libvirt APIs.
+
+This package is replaced by the new `libvirt.org/go/libvirtxml
+<go/libvirtxml.html>`__ package in order to switch to using `semver
+<https://semver.org/>`__ and `Go modules <https://golang.org/ref/mod>`__.
+Aside from the changed import path and versioning scheme, the new package API
+is fully compatible with this legacy package.
+
+Software currently using this package will keep working, but no further
+development will take place. libvirt XML scheme elements/attributes introduced
+after 7.4.0 will never be available. Authors are strongly recommended to switch
+imports to point to the new package, to prepare for future Go toolchains
+which will mandate Go module support and semver.
 
 For details of Go specific behaviour consult the
 `Go package documentation <https://pkg.go.dev/libvirt.org/libvirt-go-xml>`__.
diff --git a/docs/libvirt-go.rst b/docs/libvirt-go.rst
index f2d3f80fb2..7dd78b5f6e 100644
--- a/docs/libvirt-go.rst
+++ b/docs/libvirt-go.rst
@@ -1,9 +1,22 @@
-=======================
-Libvirt Go Language API
-=======================
+================================================
+Obsolete libvirt Go Language API (no Go modules)
+================================================
 
-The `Go <https://golang.org/>`__ package ``libvirt.org/libvirt-go`` provides
-`CGo <https://golang.org/cmd/cgo/>`__ binding from the OS native Libvirt API.
+This obsolete `Go <https://golang.org/>`__ package ``libvirt.org/libvirt-go``
+provided `CGo <https://golang.org/cmd/cgo/>`__ binding from the OS native
+Libvirt API.
+
+This package is replaced by the new `libvirt.org/go/libvirt <go/libvirt.html>`__
+package in order to switch to using `semver <https://semver.org/>`__ and
+`Go modules <https://golang.org/ref/mod>`__. Aside from the changed
+import path and versioning scheme, the new package API is fully compatible
+with this legacy package.
+
+Software currently using this package will keep working, but no further
+development will take place. libvirt APIs/constants introduced after
+7.4.0 will never be available. Authors are strongly recommended to switch
+imports to point to the new package, to prepare for future Go toolchains
+which will mandate Go module support and semver.
 
 In general the Go representation is a direct 1-1 mapping from native API
 concepts to Go, so the native API documentation should serve as a reference
diff --git a/docs/meson.build b/docs/meson.build
index bee0d80d53..4497f7270f 100644
--- a/docs/meson.build
+++ b/docs/meson.build
@@ -297,6 +297,7 @@ html_xslt_gen = []
 # --- end of XSLT processing ---
 
 subdir('fonts')
+subdir('go')
 subdir('html')
 subdir('internals')
 subdir('js')
-- 
2.31.1

On Mon, Jun 07, 2021 at 02:38:34PM +0100, Daniel P. Berrangé wrote:
> +================================================
> +Obsolete libvirt Go Language API (no Go modules)
> +================================================
>
> -The `Go <https://golang.org/>`__ package ``libvirt.org/libvirt-go`` provides
> -`CGo <https://golang.org/cmd/cgo/>`__ binding from the OS native Libvirt API.
> +This obsolete `Go <https://golang.org/>`__ package ``libvirt.org/libvirt-go``

Maybe "The obsolete"? I'll leave that up to you, on account of you
being a native speaker and all :)

Either way,

  Reviewed-by: Andrea Bolognani <abologna@redhat.com>

Thanks for putting up with my review comments!

-- 
Andrea Bolognani / Red Hat / Virtualization