[PATCH 0/2] configure: Check that sphinx-build is using Python 3

[PATCH 0/2] configure: Check that sphinx-build is using Python 3

[Peter Maydell]

We want to assume that all the Python we write is running
with at least Python 3.5; configure checks that for our scripts, but
Sphinx extensions run with whatever Python version sphinx-build
itself is using. At the moment our Sphinx extensions all work under
Python 2, but the one I'm working on for handling parsing QAPI docs
out of the JSON is going to want to include some of the scripts/qapi
Python which is more complicated and definitely now 3-only.  In any
case, allowing some bits of our Python code to run under Python 2
is setting a beartrap for our future selves. It's nicer to fail
cleanly rather than let users stumble into corner cases we don't
test and don't want to support even if they happen to work today.

Patch 1 adds a --sphinx-build=/path/to/binary option, so that
if the user has a system where the default 'sphinx-build' on
the $PATH is Python 2 they can tell configure to use a different one.

Patch 2 makes the Sphinx conf.py fail for old Pythons, and
makes configure handle and present the error to the user.

Alex: do you have a way to test this patchset with readthedocs
before it hits master? I'm not sure what version of Python
their sphinx-build is using. If we need to I think we can
force a Python version with a .readthedocs.yml file in our
git repo:
https://docs.readthedocs.io/en/stable/config-file/v2.html
but if they default to a new enough Python anyway then we
needn't bother.

thanks
-- PMM

Peter Maydell (2):
  configure: Allow user to specify sphinx-build binary
  configure: Check that sphinx-build is using Python 3

 configure    | 22 +++++++++++++++++++---
 Makefile     |  2 +-
 docs/conf.py | 10 ++++++++++
 3 files changed, 30 insertions(+), 4 deletions(-)

-- 
2.20.1

[PATCH 1/2] configure: Allow user to specify sphinx-build binary

[Peter Maydell]

Currently we insist on using 'sphinx-build' from the $PATH;
allow the user to specify the binary to use. This will be
more useful as we become pickier about the capabilities
we require (eg needing a Python 3 sphinx-build).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
I went with the most common convention for specifying "here's
an executable", like --make=, --install=, --python=....

The only odd one out for our current configure options seems to be
that we want --with-git=GIT, not --git=GIT. You could argue that
that's a better convention, but it makes more sense to me to
stick with the convention we currently mostly have. (Perhaps
we should even change --with-git= to --git= ?)

 configure | 10 +++++++++-
 Makefile  |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 5095f017283..830f325822a 100755
--- a/configure
+++ b/configure
@@ -584,6 +584,7 @@ query_pkg_config() {
 }
 pkg_config=query_pkg_config
 sdl2_config="${SDL2_CONFIG-${cross_prefix}sdl2-config}"
+sphinx_build=sphinx-build
 
 # If the user hasn't specified ARFLAGS, default to 'rv', just as make does.
 ARFLAGS="${ARFLAGS-rv}"
@@ -975,6 +976,8 @@ for opt do
   ;;
   --python=*) python="$optarg"
   ;;
+  --sphinx-build=*) sphinx_build="$optarg"
+  ;;
   --gcov=*) gcov_tool="$optarg"
   ;;
   --smbd=*) smbd="$optarg"
@@ -1677,6 +1680,7 @@ Advanced options (experts only):
   --make=MAKE              use specified make [$make]
   --install=INSTALL        use specified install [$install]
   --python=PYTHON          use specified python [$python]
+  --sphinx-build=SPHINX    use specified sphinx-build [$sphinx_build]
   --smbd=SMBD              use specified smbd [$smbd]
   --with-git=GIT           use specified git [$git]
   --static                 enable static build [$static]
@@ -4799,7 +4803,7 @@ has_sphinx_build() {
     # sphinx-build doesn't exist at all or if it is too old.
     mkdir -p "$TMPDIR1/sphinx"
     touch "$TMPDIR1/sphinx/index.rst"
-    sphinx-build -c "$source_path/docs" -b html "$TMPDIR1/sphinx" "$TMPDIR1/sphinx/out" >/dev/null 2>&1
+    $sphinx_build -c "$source_path/docs" -b html "$TMPDIR1/sphinx" "$TMPDIR1/sphinx/out" >/dev/null 2>&1
 }
 
 # Check if tools are available to build documentation.
@@ -6474,6 +6478,9 @@ echo "QEMU_LDFLAGS      $QEMU_LDFLAGS"
 echo "make              $make"
 echo "install           $install"
 echo "python            $python ($python_version)"
+if test "$docs" != "no"; then
+    echo "sphinx-build      $sphinx_build"
+fi
 echo "slirp support     $slirp $(echo_version $slirp $slirp_version)"
 if test "$slirp" != "no" ; then
     echo "smbd              $smbd"
@@ -7503,6 +7510,7 @@ echo "INSTALL_DATA=$install -c -m 0644" >> $config_host_mak
 echo "INSTALL_PROG=$install -c -m 0755" >> $config_host_mak
 echo "INSTALL_LIB=$install -c -m 0644" >> $config_host_mak
 echo "PYTHON=$python" >> $config_host_mak
+echo "SPHINX_BUILD=$sphinx_build" >> $config_host_mak
 echo "CC=$cc" >> $config_host_mak
 if $iasl -h > /dev/null 2>&1; then
   echo "IASL=$iasl" >> $config_host_mak
diff --git a/Makefile b/Makefile
index a6f5d440828..1f37523b528 100644
--- a/Makefile
+++ b/Makefile
@@ -1024,7 +1024,7 @@ sphinxdocs: $(MANUAL_BUILDDIR)/devel/index.html \
 # Note the use of different doctree for each (manual, builder) tuple;
 # this works around Sphinx not handling parallel invocation on
 # a single doctree: https://github.com/sphinx-doc/sphinx/issues/2946
-build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" sphinx-build $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
+build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" $(SPHINX_BUILD) $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
 # We assume all RST files in the manual's directory are used in it
 manual-deps = $(wildcard $(SRC_PATH)/docs/$1/*.rst) \
               $(wildcard $(SRC_PATH)/docs/$1/*.rst.inc) \
-- 
2.20.1

[PATCH 2/2] configure: Check that sphinx-build is using Python 3

[Peter Maydell]

Currently configure's has_sphinx_build() check simply runs a dummy
sphinx-build and either passes or fails.  This means that "no
sphinx-build at all" and "sphinx-build exists but is too old" are
both reported the same way.

Further, we want to assume that all the Python we write is running
with at least Python 3.5; configure checks that for our scripts, but
Sphinx extensions run with whatever Python version sphinx-build
itself is using.

Add a check to our conf.py which makes sphinx-build fail if it would
be running our extensions with an old Python, and handle this
in configure so we can report failure helpfully to the user.
This will mean that configure --enable-docs will fail like this
if the sphinx-build provided is not suitable:

Warning: sphinx-build exists but it is either too old or uses too old a Python version

ERROR: User requested feature docs
       configure was not able to find it.
       Install texinfo, Perl/perl-podlators and a Python 3 version of python-sphinx

(As usual, the default is to simply not build the docs, as we would
if sphinx-build wasn't present at all.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
At the moment our Sphinx extensions all work under Python 2;
but the one for handling parsing QAPI docs out of the JSON is going
to want to include some of the scripts/qapi Python which is more
complicated and definitely now 3-only.  In any case it's nicer to
fail cleanly rather than let users stumble into corner cases we don't
test and don't want to support even if they happen to work today.
---
 configure    | 12 ++++++++++--
 docs/conf.py | 10 ++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 830f325822a..95055f2e9dd 100755
--- a/configure
+++ b/configure
@@ -4808,11 +4808,19 @@ has_sphinx_build() {
 
 # Check if tools are available to build documentation.
 if test "$docs" != "no" ; then
-  if has makeinfo && has pod2man && has_sphinx_build; then
+  if has_sphinx_build; then
+    sphinx_ok=yes
+  else
+    sphinx_ok=no
+  fi
+  if has makeinfo && has pod2man && test "$sphinx_ok" = "yes"; then
     docs=yes
   else
     if test "$docs" = "yes" ; then
-      feature_not_found "docs" "Install texinfo, Perl/perl-podlators and python-sphinx"
+      if has $sphinx_build && test "$sphinx_ok" != "yes"; then
+        echo "Warning: $sphinx_build exists but it is either too old or uses too old a Python version" >&2
+      fi
+      feature_not_found "docs" "Install texinfo, Perl/perl-podlators and a Python 3 version of python-sphinx"
     fi
     docs=no
   fi
diff --git a/docs/conf.py b/docs/conf.py
index ee7faa6b4e7..7588bf192ee 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -28,6 +28,16 @@
 
 import os
 import sys
+import sphinx
+from sphinx.errors import VersionRequirementError
+
+# Make Sphinx fail cleanly if using an old Python, rather than obscurely
+# failing because some code in one of our extensions doesn't work there.
+# Unfortunately this doesn't display very neatly (there's an unavoidable
+# Python backtrace) but at least the information gets printed...
+if sys.version_info < (3,5):
+    raise VersionRequirementError(
+        "QEMU requires a Sphinx that uses Python 3.5 or better\n")
 
 # The per-manual conf.py will set qemu_docdir for a single-manual build;
 # otherwise set it here if this is an entire-manual-set build.
-- 
2.20.1

Re: [PATCH 1/2] configure: Allow user to specify sphinx-build binary

[Alex Bennée]

Peter Maydell <peter.maydell@linaro.org> writes:

> Currently we insist on using 'sphinx-build' from the $PATH;
> allow the user to specify the binary to use. This will be
> more useful as we become pickier about the capabilities
> we require (eg needing a Python 3 sphinx-build).
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
> I went with the most common convention for specifying "here's
> an executable", like --make=, --install=, --python=....
>
> The only odd one out for our current configure options seems to be
> that we want --with-git=GIT, not --git=GIT. You could argue that
> that's a better convention, but it makes more sense to me to
> stick with the convention we currently mostly have. (Perhaps
> we should even change --with-git= to --git= ?)
>
>  configure | 10 +++++++++-
>  Makefile  |  2 +-
>  2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/configure b/configure
> index 5095f017283..830f325822a 100755
> --- a/configure
> +++ b/configure
> @@ -584,6 +584,7 @@ query_pkg_config() {
>  }
>  pkg_config=query_pkg_config
>  sdl2_config="${SDL2_CONFIG-${cross_prefix}sdl2-config}"
> +sphinx_build=sphinx-build
>  
>  # If the user hasn't specified ARFLAGS, default to 'rv', just as make does.
>  ARFLAGS="${ARFLAGS-rv}"
> @@ -975,6 +976,8 @@ for opt do
>    ;;
>    --python=*) python="$optarg"
>    ;;
> +  --sphinx-build=*) sphinx_build="$optarg"
> +  ;;
>    --gcov=*) gcov_tool="$optarg"
>    ;;
>    --smbd=*) smbd="$optarg"
> @@ -1677,6 +1680,7 @@ Advanced options (experts only):
>    --make=MAKE              use specified make [$make]
>    --install=INSTALL        use specified install [$install]
>    --python=PYTHON          use specified python [$python]
> +  --sphinx-build=SPHINX    use specified sphinx-build [$sphinx_build]
>    --smbd=SMBD              use specified smbd [$smbd]
>    --with-git=GIT           use specified git [$git]
>    --static                 enable static build [$static]
> @@ -4799,7 +4803,7 @@ has_sphinx_build() {
>      # sphinx-build doesn't exist at all or if it is too old.
>      mkdir -p "$TMPDIR1/sphinx"
>      touch "$TMPDIR1/sphinx/index.rst"
> -    sphinx-build -c "$source_path/docs" -b html "$TMPDIR1/sphinx" "$TMPDIR1/sphinx/out" >/dev/null 2>&1
> +    $sphinx_build -c "$source_path/docs" -b html "$TMPDIR1/sphinx" "$TMPDIR1/sphinx/out" >/dev/null 2>&1
>  }
>  
>  # Check if tools are available to build documentation.
> @@ -6474,6 +6478,9 @@ echo "QEMU_LDFLAGS      $QEMU_LDFLAGS"
>  echo "make              $make"
>  echo "install           $install"
>  echo "python            $python ($python_version)"
> +if test "$docs" != "no"; then
> +    echo "sphinx-build      $sphinx_build"
> +fi
>  echo "slirp support     $slirp $(echo_version $slirp $slirp_version)"
>  if test "$slirp" != "no" ; then
>      echo "smbd              $smbd"
> @@ -7503,6 +7510,7 @@ echo "INSTALL_DATA=$install -c -m 0644" >> $config_host_mak
>  echo "INSTALL_PROG=$install -c -m 0755" >> $config_host_mak
>  echo "INSTALL_LIB=$install -c -m 0644" >> $config_host_mak
>  echo "PYTHON=$python" >> $config_host_mak
> +echo "SPHINX_BUILD=$sphinx_build" >> $config_host_mak
>  echo "CC=$cc" >> $config_host_mak
>  if $iasl -h > /dev/null 2>&1; then
>    echo "IASL=$iasl" >> $config_host_mak
> diff --git a/Makefile b/Makefile
> index a6f5d440828..1f37523b528 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1024,7 +1024,7 @@ sphinxdocs: $(MANUAL_BUILDDIR)/devel/index.html \
>  # Note the use of different doctree for each (manual, builder) tuple;
>  # this works around Sphinx not handling parallel invocation on
>  # a single doctree: https://github.com/sphinx-doc/sphinx/issues/2946
> -build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" sphinx-build $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
> +build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" $(SPHINX_BUILD) $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
>  # We assume all RST files in the manual's directory are used in it
>  manual-deps = $(wildcard $(SRC_PATH)/docs/$1/*.rst) \
>                $(wildcard $(SRC_PATH)/docs/$1/*.rst.inc) \


-- 
Alex Bennée

Re: [PATCH 2/2] configure: Check that sphinx-build is using Python 3

[Alex Bennée]

Peter Maydell <peter.maydell@linaro.org> writes:

> Currently configure's has_sphinx_build() check simply runs a dummy
> sphinx-build and either passes or fails.  This means that "no
> sphinx-build at all" and "sphinx-build exists but is too old" are
> both reported the same way.
>
> Further, we want to assume that all the Python we write is running
> with at least Python 3.5; configure checks that for our scripts, but
> Sphinx extensions run with whatever Python version sphinx-build
> itself is using.
>
> Add a check to our conf.py which makes sphinx-build fail if it would
> be running our extensions with an old Python, and handle this
> in configure so we can report failure helpfully to the user.
> This will mean that configure --enable-docs will fail like this
> if the sphinx-build provided is not suitable:
>
> Warning: sphinx-build exists but it is either too old or uses too old a Python version
>
> ERROR: User requested feature docs
>        configure was not able to find it.
>        Install texinfo, Perl/perl-podlators and a Python 3 version of python-sphinx
>
> (As usual, the default is to simply not build the docs, as we would
> if sphinx-build wasn't present at all.)
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
> At the moment our Sphinx extensions all work under Python 2;
> but the one for handling parsing QAPI docs out of the JSON is going
> to want to include some of the scripts/qapi Python which is more
> complicated and definitely now 3-only.  In any case it's nicer to
> fail cleanly rather than let users stumble into corner cases we don't
> test and don't want to support even if they happen to work today.
> ---
>  configure    | 12 ++++++++++--
>  docs/conf.py | 10 ++++++++++
>  2 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/configure b/configure
> index 830f325822a..95055f2e9dd 100755
> --- a/configure
> +++ b/configure
> @@ -4808,11 +4808,19 @@ has_sphinx_build() {
>  
>  # Check if tools are available to build documentation.
>  if test "$docs" != "no" ; then
> -  if has makeinfo && has pod2man && has_sphinx_build; then
> +  if has_sphinx_build; then
> +    sphinx_ok=yes
> +  else
> +    sphinx_ok=no
> +  fi
> +  if has makeinfo && has pod2man && test "$sphinx_ok" = "yes"; then
>      docs=yes
>    else
>      if test "$docs" = "yes" ; then
> -      feature_not_found "docs" "Install texinfo, Perl/perl-podlators and python-sphinx"
> +      if has $sphinx_build && test "$sphinx_ok" != "yes"; then
> +        echo "Warning: $sphinx_build exists but it is either too old or uses too old a Python version" >&2
> +      fi
> +      feature_not_found "docs" "Install texinfo, Perl/perl-podlators and a Python 3 version of python-sphinx"
>      fi
>      docs=no
>    fi
> diff --git a/docs/conf.py b/docs/conf.py
> index ee7faa6b4e7..7588bf192ee 100644
> --- a/docs/conf.py
> +++ b/docs/conf.py
> @@ -28,6 +28,16 @@
>  
>  import os
>  import sys
> +import sphinx
> +from sphinx.errors import VersionRequirementError
> +
> +# Make Sphinx fail cleanly if using an old Python, rather than obscurely
> +# failing because some code in one of our extensions doesn't work there.
> +# Unfortunately this doesn't display very neatly (there's an unavoidable
> +# Python backtrace) but at least the information gets printed...
> +if sys.version_info < (3,5):
> +    raise VersionRequirementError(
> +        "QEMU requires a Sphinx that uses Python 3.5 or better\n")
>  
>  # The per-manual conf.py will set qemu_docdir for a single-manual build;
>  # otherwise set it here if this is an entire-manual-set build.


-- 
Alex Bennée

Re: [PATCH 1/2] configure: Allow user to specify sphinx-build binary

[Markus Armbruster]

Peter Maydell <peter.maydell@linaro.org> writes:

> Currently we insist on using 'sphinx-build' from the $PATH;
> allow the user to specify the binary to use. This will be
> more useful as we become pickier about the capabilities
> we require (eg needing a Python 3 sphinx-build).
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> I went with the most common convention for specifying "here's
> an executable", like --make=, --install=, --python=....
>
> The only odd one out for our current configure options seems to be
> that we want --with-git=GIT, not --git=GIT. You could argue that
> that's a better convention,

It's the one Autoconf uses.

>                             but it makes more sense to me to
> stick with the convention we currently mostly have. (Perhaps
> we should even change --with-git= to --git= ?)

Paolo, any implications on the Meson conversion?

Re: [PATCH 1/2] configure: Allow user to specify sphinx-build binary

[Paolo Bonzini]

On 04/02/20 11:39, Markus Armbruster wrote:
> Peter Maydell <peter.maydell@linaro.org> writes:
> 
>> Currently we insist on using 'sphinx-build' from the $PATH;
>> allow the user to specify the binary to use. This will be
>> more useful as we become pickier about the capabilities
>> we require (eg needing a Python 3 sphinx-build).
>>
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>> ---
>> I went with the most common convention for specifying "here's
>> an executable", like --make=, --install=, --python=....
>>
>> The only odd one out for our current configure options seems to be
>> that we want --with-git=GIT, not --git=GIT. You could argue that
>> that's a better convention,
> 
> It's the one Autoconf uses.
> 
>>                             but it makes more sense to me to
>> stick with the convention we currently mostly have. (Perhaps
>> we should even change --with-git= to --git= ?)
> 
> Paolo, any implications on the Meson conversion?

Nope, there will still be a handwritten configure script (and in the
beginning it will be pretty much the same as now; in due time, it will
handle command line parsing only).

Paolo

Re: [PATCH 1/2] configure: Allow user to specify sphinx-build binary

[Wainer dos Santos Moschetta]

On 2/3/20 11:25 AM, Peter Maydell wrote:
> Currently we insist on using 'sphinx-build' from the $PATH;
> allow the user to specify the binary to use. This will be
> more useful as we become pickier about the capabilities
> we require (eg needing a Python 3 sphinx-build).
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> I went with the most common convention for specifying "here's
> an executable", like --make=, --install=, --python=....
>
> The only odd one out for our current configure options seems to be
> that we want --with-git=GIT, not --git=GIT. You could argue that
> that's a better convention, but it makes more sense to me to
> stick with the convention we currently mostly have. (Perhaps
> we should even change --with-git= to --git= ?)
>
>   configure | 10 +++++++++-
>   Makefile  |  2 +-
>   2 files changed, 10 insertions(+), 2 deletions(-)


Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>


>
> diff --git a/configure b/configure
> index 5095f017283..830f325822a 100755
> --- a/configure
> +++ b/configure
> @@ -584,6 +584,7 @@ query_pkg_config() {
>   }
>   pkg_config=query_pkg_config
>   sdl2_config="${SDL2_CONFIG-${cross_prefix}sdl2-config}"
> +sphinx_build=sphinx-build
>   
>   # If the user hasn't specified ARFLAGS, default to 'rv', just as make does.
>   ARFLAGS="${ARFLAGS-rv}"
> @@ -975,6 +976,8 @@ for opt do
>     ;;
>     --python=*) python="$optarg"
>     ;;
> +  --sphinx-build=*) sphinx_build="$optarg"
> +  ;;
>     --gcov=*) gcov_tool="$optarg"
>     ;;
>     --smbd=*) smbd="$optarg"
> @@ -1677,6 +1680,7 @@ Advanced options (experts only):
>     --make=MAKE              use specified make [$make]
>     --install=INSTALL        use specified install [$install]
>     --python=PYTHON          use specified python [$python]
> +  --sphinx-build=SPHINX    use specified sphinx-build [$sphinx_build]
>     --smbd=SMBD              use specified smbd [$smbd]
>     --with-git=GIT           use specified git [$git]
>     --static                 enable static build [$static]
> @@ -4799,7 +4803,7 @@ has_sphinx_build() {
>       # sphinx-build doesn't exist at all or if it is too old.
>       mkdir -p "$TMPDIR1/sphinx"
>       touch "$TMPDIR1/sphinx/index.rst"
> -    sphinx-build -c "$source_path/docs" -b html "$TMPDIR1/sphinx" "$TMPDIR1/sphinx/out" >/dev/null 2>&1
> +    $sphinx_build -c "$source_path/docs" -b html "$TMPDIR1/sphinx" "$TMPDIR1/sphinx/out" >/dev/null 2>&1
>   }
>   
>   # Check if tools are available to build documentation.
> @@ -6474,6 +6478,9 @@ echo "QEMU_LDFLAGS      $QEMU_LDFLAGS"
>   echo "make              $make"
>   echo "install           $install"
>   echo "python            $python ($python_version)"
> +if test "$docs" != "no"; then
> +    echo "sphinx-build      $sphinx_build"
> +fi
>   echo "slirp support     $slirp $(echo_version $slirp $slirp_version)"
>   if test "$slirp" != "no" ; then
>       echo "smbd              $smbd"
> @@ -7503,6 +7510,7 @@ echo "INSTALL_DATA=$install -c -m 0644" >> $config_host_mak
>   echo "INSTALL_PROG=$install -c -m 0755" >> $config_host_mak
>   echo "INSTALL_LIB=$install -c -m 0644" >> $config_host_mak
>   echo "PYTHON=$python" >> $config_host_mak
> +echo "SPHINX_BUILD=$sphinx_build" >> $config_host_mak
>   echo "CC=$cc" >> $config_host_mak
>   if $iasl -h > /dev/null 2>&1; then
>     echo "IASL=$iasl" >> $config_host_mak
> diff --git a/Makefile b/Makefile
> index a6f5d440828..1f37523b528 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1024,7 +1024,7 @@ sphinxdocs: $(MANUAL_BUILDDIR)/devel/index.html \
>   # Note the use of different doctree for each (manual, builder) tuple;
>   # this works around Sphinx not handling parallel invocation on
>   # a single doctree: https://github.com/sphinx-doc/sphinx/issues/2946
> -build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" sphinx-build $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
> +build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" $(SPHINX_BUILD) $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
>   # We assume all RST files in the manual's directory are used in it
>   manual-deps = $(wildcard $(SRC_PATH)/docs/$1/*.rst) \
>                 $(wildcard $(SRC_PATH)/docs/$1/*.rst.inc) \

Re: [PATCH 2/2] configure: Check that sphinx-build is using Python 3

[Wainer dos Santos Moschetta]

On 2/3/20 11:25 AM, Peter Maydell wrote:
> Currently configure's has_sphinx_build() check simply runs a dummy
> sphinx-build and either passes or fails.  This means that "no
> sphinx-build at all" and "sphinx-build exists but is too old" are
> both reported the same way.
>
> Further, we want to assume that all the Python we write is running
> with at least Python 3.5; configure checks that for our scripts, but
> Sphinx extensions run with whatever Python version sphinx-build
> itself is using.
>
> Add a check to our conf.py which makes sphinx-build fail if it would
> be running our extensions with an old Python, and handle this
> in configure so we can report failure helpfully to the user.
> This will mean that configure --enable-docs will fail like this
> if the sphinx-build provided is not suitable:
>
> Warning: sphinx-build exists but it is either too old or uses too old a Python version
>
> ERROR: User requested feature docs
>         configure was not able to find it.
>         Install texinfo, Perl/perl-podlators and a Python 3 version of python-sphinx
>
> (As usual, the default is to simply not build the docs, as we would
> if sphinx-build wasn't present at all.)
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> At the moment our Sphinx extensions all work under Python 2;
> but the one for handling parsing QAPI docs out of the JSON is going
> to want to include some of the scripts/qapi Python which is more
> complicated and definitely now 3-only.  In any case it's nicer to
> fail cleanly rather than let users stumble into corner cases we don't
> test and don't want to support even if they happen to work today.
> ---
>   configure    | 12 ++++++++++--
>   docs/conf.py | 10 ++++++++++
>   2 files changed, 20 insertions(+), 2 deletions(-)


Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>



>
> diff --git a/configure b/configure
> index 830f325822a..95055f2e9dd 100755
> --- a/configure
> +++ b/configure
> @@ -4808,11 +4808,19 @@ has_sphinx_build() {
>   
>   # Check if tools are available to build documentation.
>   if test "$docs" != "no" ; then
> -  if has makeinfo && has pod2man && has_sphinx_build; then
> +  if has_sphinx_build; then
> +    sphinx_ok=yes
> +  else
> +    sphinx_ok=no
> +  fi
> +  if has makeinfo && has pod2man && test "$sphinx_ok" = "yes"; then
>       docs=yes
>     else
>       if test "$docs" = "yes" ; then
> -      feature_not_found "docs" "Install texinfo, Perl/perl-podlators and python-sphinx"
> +      if has $sphinx_build && test "$sphinx_ok" != "yes"; then
> +        echo "Warning: $sphinx_build exists but it is either too old or uses too old a Python version" >&2
> +      fi
> +      feature_not_found "docs" "Install texinfo, Perl/perl-podlators and a Python 3 version of python-sphinx"
>       fi
>       docs=no
>     fi
> diff --git a/docs/conf.py b/docs/conf.py
> index ee7faa6b4e7..7588bf192ee 100644
> --- a/docs/conf.py
> +++ b/docs/conf.py
> @@ -28,6 +28,16 @@
>   
>   import os
>   import sys
> +import sphinx
> +from sphinx.errors import VersionRequirementError
> +
> +# Make Sphinx fail cleanly if using an old Python, rather than obscurely
> +# failing because some code in one of our extensions doesn't work there.
> +# Unfortunately this doesn't display very neatly (there's an unavoidable
> +# Python backtrace) but at least the information gets printed...
> +if sys.version_info < (3,5):
> +    raise VersionRequirementError(
> +        "QEMU requires a Sphinx that uses Python 3.5 or better\n")
>   
>   # The per-manual conf.py will set qemu_docdir for a single-manual build;
>   # otherwise set it here if this is an entire-manual-set build.