python3-modules: build pillow without FreeType

With the sync no longer breaking on it, sles-12sp5 gets as far as
compiling pillow - and fails there:

  src/_imagingft.c: error: implicit declaration of function
  'FT_Set_Named_Instance'

pillow 12.0.0 removed the FREETYPE_MAJOR/MINOR guards around the variable
font API (python-pillow/Pillow#9159), so _imagingft now calls
FT_Done_MM_Var and FT_Set_Named_Instance unconditionally and needs
FreeType >= 2.9.1. pillow's setup.py only probes whether FreeType is
present, never which version, so it enables the module regardless.

sles-12sp5 ships FreeType 2.6.3 and nothing newer is installable:

  freetype2-devel-2.6.3-7.15.1  (the only version in our sles12sp5 repo)
  FREETYPE_MAJOR 2 / FREETYPE_MINOR 6 / FREETYPE_PATCH 3
  ftmm.h declares neither of the two functions
  libfreetype.so.6 exports neither of them

Note the last line: the runtime library is equally old, so building
against a newer FreeType without also shipping it would only move the
failure to the customer's machine - the SONAME stayed libfreetype.so.6
across all these versions, and we link with -z now, so it would fail at
import rather than lazily.

We never render text with PIL - it is used for image IO only, there is no
ImageFont, ImageDraw or truetype anywhere in the repo - so disable the
feature instead of shipping a FreeType. master already disables avif the
same way, because libavif is unavailable on debian-12.

Where the option goes matters: pip applies --config-settings only to
requirements named on the command line, never to the ones it reads from a
"-r" file, and both builds install from "-r". So it has to be attached to
the requirement itself rather than to the pip invocation. For Bazel that
is the generated per-module requirements file. For the .venv it means
installing pillow up front, because the requirements file pipenv hands to
pip is not ours to extend and pipenv has no Pipfile syntax for per-package
pip options. Requirement and hashes come from Pipfile.lock, so pillow
stays pinned and hash checked, and the sync afterwards finds it already
satisfied and leaves it alone. (get_pip_options() keeps its numpy entry,
which is ineffective for the same reason, but changing how numpy builds is
out of scope here.)

Verified by rebuilding the venv from scratch with PIP_NO_BINARY=pillow, so
that pillow is built from source exactly as on sles-12sp5: PIL reports
freetype2 False with no _imagingft*.so, while a normal wheel based rebuild
is unaffected. "make test-mypy" still reports no issues in 7436 source
files.

Change-Id: I02a16f5f1007b0f8befd9f0c1f68a4c8822a0f65

Author: TimotheusBachinger

Makefile

@@ -439,6 +439,15 @@ Pipfile.lock: Pipfile
 # only bites on distros without a matching wheel, which made it look like a
 # sles-12sp5 specific failure.
 #
+# pillow gets installed up front, because it needs the same "build without
+# FreeType" treatment the Bazel build applies (see the rationale in
+# omd/packages/python3-modules/build-python3-modules.bzl): on sles-12sp5 it has no
+# wheel and the system FreeType 2.6.3 is too old for pillow 12. It cannot be done
+# as part of the sync, because pip applies --config-settings only to requirements
+# named on the command line, never to the ones it reads from the "-r" file pipenv
+# hands it. Requirement and hashes come from Pipfile.lock, so this stays pinned and
+# hash checked, and the sync afterwards just finds it already satisfied.
+#
 # We still need our own packages laid out so that mypy can type check them:
 # https://github.com/python/mypy/issues/13392
 # --config-settings editable_mode=compat is setuptools' supported replacement
@@ -455,7 +464,13 @@ Pipfile.lock: Pipfile
 	      echo "Cleaning up .venv before sync..."; \
 	      $(RM) -r .venv; \
 	    fi; \
-	    ( PIP_CONSTRAINT=temporary_pipenv_constraints.txt SKIP_MAKEFILE_CALL=1 VIRTUAL_ENV="" $(PIPENV) sync --python $(PYTHON_MAJOR_DOT_MINOR) --dev \
+	    ( SKIP_MAKEFILE_CALL=1 VIRTUAL_ENV="" $(PIPENV) run python -c "" \
+	      && echo "Installing pillow without FreeType support..." \
+	      && PILLOW_REQUIREMENTS=$$(mktemp) \
+	      && .venv/bin/python -c 'import json; e = json.load(open("Pipfile.lock"))["default"]["pillow"]; print("pillow" + e["version"], "--config-settings freetype=disable", *("--hash=" + h for h in e["hashes"]))' > $$PILLOW_REQUIREMENTS \
+	      && PIP_CONSTRAINT=temporary_pipenv_constraints.txt .venv/bin/python -m pip install --quiet --no-deps -r $$PILLOW_REQUIREMENTS \
+	      && $(RM) $$PILLOW_REQUIREMENTS \
+	      && PIP_CONSTRAINT=temporary_pipenv_constraints.txt SKIP_MAKEFILE_CALL=1 VIRTUAL_ENV="" $(PIPENV) sync --python $(PYTHON_MAJOR_DOT_MINOR) --dev \
 	      && echo "Reinstalling editable packages in compat mode..." \
 	      && .venv/bin/python -m pip install --quiet --no-deps --no-build-isolation --config-settings editable_mode=compat \
 	           $$(.venv/bin/python -c 'import json; print(" ".join("-e " + e["path"] for s in ("default", "develop") for e in json.load(open("Pipfile.lock"))[s].values() if e.get("editable")))') \

omd/packages/python3-modules/build-python3-modules.bzl

@@ -9,6 +9,22 @@ def get_pip_options(module_name):
         "numpy": '--config-settings=setup-args="-Dallow-noblas=true"',
     }.get(module_name, "")
 
+def get_requirement_options(module_name):
+    """Options that have to be attached to the requirement itself.
+
+    pip applies --config-settings only to requirements named on the command line, never
+    to the ones it reads from a "-r" file. We install every module via "-r", so passing
+    them through get_pip_options() above would silently have no effect.
+    """
+    return {
+        # pillow 12.0.0 removed the FREETYPE_MAJOR/MINOR guards around the variable font
+        # API (https://github.com/python-pillow/Pillow/pull/9159), so building _imagingft
+        # now needs FreeType >= 2.9.1. sles-12sp5 only has 2.6.3 and nothing newer is
+        # installable there. We never render text with PIL - it is only used for image IO -
+        # so we simply disable it.
+        "pillow": " --config-settings freetype=disable",
+    }.get(module_name, "")
+
 def create_requirements_file(name, outs):
     """This macro is creating a requirements file per module.
     """
@@ -17,7 +33,7 @@ def create_requirements_file(name, outs):
         outs = outs,
         cmd = """
            echo "%s" > $@
-        """ % packages[name],
+        """ % (packages[name] + get_requirement_options(name)),
     )
 
 def build_python_module(name, srcs, outs, cmd, **kwargs):