conan make generator does not set CONAN_CXXFLAGS as expected - c++

Question

When running conan install . -s arch=x86 on an x86_64 System, I expect a compiler option like CONAN_CXXFLAGS_MYLIB=-m32 in the generated conanbuildinfo.mak file, but there is no such an option.
First, the contents of the conanfile.txt:
[requires]
mylib/1.0#demo/dev
[generators]
make
Here is the output of the install command (cmake has special treatment, because it is only a tool):
$ conan install . -s cmake:arch=x86_64 -s arch=x86
Configuration:
[settings]
arch=x86
arch_build=x86_64
build_type=Release
compiler=gcc
compiler.libcxx=libstdc++11
compiler.version=9
os=Linux
os_build=Linux
cmake:arch=x86_64
[options]
[build_requires]
[env]
conanfile.txt: Installing package
Requirements
mylib/1.0#demo/dev from local cache - Cache
Packages
mylib/1.0#demo/dev:eb79ce42f6e6b4359bd7d0a65a238a4dae953257 - Cache
'''
Cross-build from 'Linux:x86_64' to 'Linux:x86'
Installing (downloading, building) binaries...
mylib/1.0#demo/dev: Already installed!
conanfile.txt: Generator make created conanbuildinfo.mak
conanfile.txt: Generator txt created conanbuildinfo.txt
conanfile.txt: Generated conaninfo.txt
conanfile.txt: Generated graphinfo
The generated makfe file looks like this:
#-------------------------------------------------------------------#
# Makefile variables from Conan Dependencies #
#-------------------------------------------------------------------#
CONAN_ROOT_MYLIB ?= \
/home/username/.conan/data/mylib/1.0/demo/dev/package/eb79ce42f6e6b4359bd7d0a65a238a4dae953257
CONAN_SYSROOT_MYLIB ?= \
CONAN_INCLUDE_DIRS_MYLIB += \
/home/username/.conan/data/mylib/1.0/demo/dev/package/eb79ce42f6e6b4359bd7d0a65a238a4dae953257/include
CONAN_LIB_DIRS_MYLIB += \
/home/username/.conan/data/mylib/1.0/demo/dev/package/eb79ce42f6e6b4359bd7d0a65a238a4dae953257/lib
CONAN_BIN_DIRS_MYLIB += \
CONAN_BUILD_DIRS_MYLIB += \
/home/username/.conan/data/mylib/1.0/demo/dev/package/eb79ce42f6e6b4359bd7d0a65a238a4dae953257/
CONAN_RES_DIRS_MYLIB += \
CONAN_LIBS_MYLIB += \
mylib
CONAN_SYSTEM_LIBS_MYLIB += \
CONAN_DEFINES_MYLIB += \
CONAN_CFLAGS_MYLIB += \
CONAN_CXXFLAGS_MYLIB += \
CONAN_SHAREDLINKFLAGS_MYLIB += \
CONAN_EXELINKFLAGS_MYLIB += \
CONAN_FRAMEWORKS_MYLIB += \
CONAN_FRAMEWORK_PATHS_MYLIB += \
CONAN_ROOTPATH += \
$(CONAN_ROOTPATH_MYLIB)
CONAN_SYSROOT += \
$(CONAN_SYSROOT_MYLIB)
CONAN_INCLUDE_DIRS += \
$(CONAN_INCLUDE_DIRS_MYLIB)
CONAN_LIB_DIRS += \
$(CONAN_LIB_DIRS_MYLIB)
CONAN_BIN_DIRS += \
$(CONAN_BIN_DIRS_MYLIB)
CONAN_BUILD_DIRS += \
$(CONAN_BUILD_DIRS_MYLIB)
CONAN_RES_DIRS += \
$(CONAN_RES_DIRS_MYLIB)
CONAN_LIBS += \
$(CONAN_LIBS_MYLIB)
CONAN_DEFINES += \
$(CONAN_DEFINES_MYLIB)
CONAN_CFLAGS += \
$(CONAN_CFLAGS_MYLIB)
CONAN_CXXFLAGS += \
$(CONAN_CXXFLAGS_MYLIB)
CONAN_SHAREDLINKFLAGS += \
$(CONAN_SHAREDLINKFLAGS_MYLIB)
CONAN_EXELINKFLAGS += \
$(CONAN_EXELINKFLAGS_MYLIB)
CONAN_FRAMEWORKS += \
$(CONAN_FRAMEWORKS_MYLIB)
CONAN_FRAMEWORK_PATHS += \
$(CONAN_FRAMEWORK_PATHS_MYLIB)
CONAN_SYSTEM_LIBS += \
$(CONAN_SYSTEM_LIBS_MYLIB)
#-------------------------------------------------------------------#
Conan knows, that this is a cross-build, it knows the compiler, it builds mylib with 32 bitness (or takes the 32 bit binaries, if found in the repo). So it should be obvious, that my app needs to be compiled with -m32.
Why is my expectation wrong?
UPDATE:
I have found the solution myself. If a conanfile.py is used with the autotools/make helper instead of the simple conanfile.txt, then it is possible to build the app with conan build ., and conan sets all compiler options and defines correctly. Here is an example of such a consumer receipt:
from conans import ConanFile, AutoToolsBuildEnvironment
from conans import tools
class AppConan(ConanFile):
name = "mayapp"
version = "1.0"
settings = "os", "compiler", "build_type", "arch"
requires = "mylib/1.0#demo/dev"
generators = "make", "virtualrunenv"
def build(self):
atools = AutoToolsBuildEnvironment(self)
atools.make()