Don't hard-code the QEMU version number into conf.py. Instead
we either pass it to sphinx-build on the command line, or
(if doing a standalone Sphinx run in a readthedocs.org setup)
extract it from the VERSION file.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190305172139.32662-12-peter.maydell@linaro.org
Message-id: 20190228145624.24885-12-peter.maydell@linaro.org
---
 Makefile     |  2 +-
 docs/conf.py | 21 ++++++++++++++++-----
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index b746d112a7f..cad585b4d6b 100644
--- a/Makefile
+++ b/Makefile
@@ -869,7 +869,7 @@ docs/version.texi: $(SRC_PATH)/VERSION
 sphinxdocs: docs/devel/index.html docs/interop/index.html
 
 # Canned command to build a single manual
-build-manual = $(call quiet-command,sphinx-build $(if $(V),,-q) -b html -d .doctrees/$1 $(SRC_PATH)/docs/$1 docs/$1 ,"SPHINX","docs/$1")
+build-manual = $(call quiet-command,sphinx-build $(if $(V),,-q) -b html -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1 $(SRC_PATH)/docs/$1 docs/$1 ,"SPHINX","docs/$1")
 # We assume all RST files in the manual's directory are used in it
 manual-deps = $(wildcard $(SRC_PATH)/docs/$1/*.rst) $(SRC_PATH)/docs/$1/conf.py $(SRC_PATH)/docs/conf.py
 
diff --git a/docs/conf.py b/docs/conf.py
index f452e424cfe..befbcc6c3e1 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -76,11 +76,22 @@ author = u'The QEMU Project Developers'
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
-#
-# The short X.Y version.
-version = u'4.0'
-# The full version, including alpha/beta/rc tags.
-release = u'4.0'
+
+# Extract this information from the VERSION file, for the benefit of
+# standalone Sphinx runs as used by readthedocs.org. Builds run from
+# the Makefile will pass version and release on the sphinx-build
+# command line, which override this.
+try:
+    extracted_version = None
+    with open(os.path.join(qemu_docdir, '../VERSION')) as f:
+        extracted_version = f.readline().strip()
+except:
+    pass
+finally:
+    if extracted_version:
+        version = release = extracted_version
+    else:
+        version = release = "unknown version"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
-- 
2.20.1