py/mkrules.mk: Add MICROPY_PREVIEW_VERSION_2.

This provides a way to enable features and changes slated for MicroPython
2.x, by running `make MICROPY_PREVIEW_VERSION_2=1`. Also supported for
the cmake ports (except Zephyr).

This is an alternative to having a 2.x development branch (or equivalently,
keeping a 1.x release branch). Any feature or change that needs to be
"hidden" until 2.x can use this flag (either in the Makefile or the
preprocessor).

A good example is changing function arguments or other public API features,
in particular to aid in improving consistency between ports.

When `MICROPY_PREVIEW_VERSION_2` is enabled, the REPL banner is amended to
say "MicroPython (with v2.0 preview) vX.Y.Z", and sys.implementation gets a
new field `_v2` set to `True`.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

.github/workflows/ports_unix.yml

@@ -55,6 +55,18 @@ jobs:
       if: failure()
       run: tests/run-tests.py --print-failures
 
+  standard_v2:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build
+      run: source tools/ci.sh && ci_unix_standard_v2_build
+    - name: Run main test suite
+      run: source tools/ci.sh && ci_unix_standard_v2_run_tests
+    - name: Print failures
+      if: failure()
+      run: tests/run-tests.py --print-failures
+
   coverage:
     runs-on: ubuntu-latest
     steps:

ports/esp32/Makefile

@@ -52,6 +52,10 @@ ifdef BOARD_VARIANT
 	IDFPY_FLAGS += -D MICROPY_BOARD_VARIANT=$(BOARD_VARIANT)
 endif
 
+ifdef MICROPY_PREVIEW_VERSION_2
+	IDFPY_FLAGS += -D MICROPY_PREVIEW_VERSION_2=1
+endif
+
 HELP_BUILD_ERROR ?= "See \033[1;31mhttps://github.com/micropython/micropython/wiki/Build-Troubleshooting\033[0m"
 
 define RUN_IDF_PY

ports/rp2/Makefile

@@ -48,6 +48,10 @@ ifdef BOARD_VARIANT
 CMAKE_ARGS += -DMICROPY_BOARD_VARIANT=$(BOARD_VARIANT)
 endif
 
+ifdef MICROPY_PREVIEW_VERSION_2
+CMAKE_ARGS += -DMICROPY_PREVIEW_VERSION_2=1
+endif
+
 HELP_BUILD_ERROR ?= "See \033[1;31mhttps://github.com/micropython/micropython/wiki/Build-Troubleshooting\033[0m"
 
 all:

py/mkrules.cmake

@@ -15,6 +15,10 @@ set(MICROPY_ROOT_POINTERS_SPLIT "${MICROPY_GENHDR_DIR}/root_pointers.split")
 set(MICROPY_ROOT_POINTERS_COLLECTED "${MICROPY_GENHDR_DIR}/root_pointers.collected")
 set(MICROPY_ROOT_POINTERS "${MICROPY_GENHDR_DIR}/root_pointers.h")
 
+if(NOT MICROPY_PREVIEW_VERSION_2)
+    set(MICROPY_PREVIEW_VERSION_2 0)
+endif()
+
 # Need to do this before extracting MICROPY_CPP_DEF below. Rest of frozen
 # manifest handling is at the end of this file.
 if(MICROPY_FROZEN_MANIFEST)
@@ -24,6 +28,12 @@ if(MICROPY_FROZEN_MANIFEST)
     )
 endif()
 
+if(MICROPY_PREVIEW_VERSION_2)
+    target_compile_definitions(${MICROPY_TARGET} PUBLIC
+        MICROPY_PREVIEW_VERSION_2=\(1\)
+    )
+endif()
+
 # Provide defaults for preprocessor flags if not already defined
 if(NOT MICROPY_CPP_FLAGS)
     get_target_property(MICROPY_CPP_INC ${MICROPY_TARGET} INCLUDE_DIRECTORIES)

py/mkrules.mk

@@ -4,6 +4,13 @@ THIS_MAKEFILE = $(lastword $(MAKEFILE_LIST))
 include $(dir $(THIS_MAKEFILE))mkenv.mk
 endif
 
+# Enable in-progress/breaking changes that are slated for MicroPython 2.x.
+MICROPY_PREVIEW_VERSION_2 ?= 0
+
+ifeq ($(MICROPY_PREVIEW_VERSION_2),1)
+CFLAGS += -DMICROPY_PREVIEW_VERSION_2=1
+endif
+
 HELP_BUILD_ERROR ?= "See \033[1;31mhttps://github.com/micropython/micropython/wiki/Build-Troubleshooting\033[0m"
 HELP_MPY_LIB_SUBMODULE ?= "\033[1;31mError: micropython-lib submodule is not initialized.\033[0m Run 'make submodules'"
 

py/modsys.c

@@ -79,19 +79,26 @@ STATIC const mp_rom_obj_tuple_t mp_sys_implementation_version_info_obj = {
     }
 };
 STATIC const MP_DEFINE_STR_OBJ(mp_sys_implementation_machine_obj, MICROPY_BANNER_MACHINE);
-#if MICROPY_PERSISTENT_CODE_LOAD
-#define SYS_IMPLEMENTATION_ELEMS \
-    MP_ROM_QSTR(MP_QSTR_micropython), \
-    MP_ROM_PTR(&mp_sys_implementation_version_info_obj), \
-    MP_ROM_PTR(&mp_sys_implementation_machine_obj), \
-    MP_ROM_INT(MPY_FILE_HEADER_INT)
-#else
-#define SYS_IMPLEMENTATION_ELEMS \
+#define SYS_IMPLEMENTATION_ELEMS_BASE \
     MP_ROM_QSTR(MP_QSTR_micropython), \
     MP_ROM_PTR(&mp_sys_implementation_version_info_obj), \
     MP_ROM_PTR(&mp_sys_implementation_machine_obj)
+
+#if MICROPY_PERSISTENT_CODE_LOAD
+#define SYS_IMPLEMENTATION_ELEMS__MPY \
+    , MP_ROM_INT(MPY_FILE_HEADER_INT)
+#else
+#define SYS_IMPLEMENTATION_ELEMS__MPY
 #endif
+
 #if MICROPY_PY_ATTRTUPLE
+#if MICROPY_PREVIEW_VERSION_2
+#define SYS_IMPLEMENTATION_ELEMS__V2 \
+    , MP_ROM_TRUE
+#else
+#define SYS_IMPLEMENTATION_ELEMS__V2
+#endif
+
 STATIC const qstr impl_fields[] = {
     MP_QSTR_name,
     MP_QSTR_version,
@@ -99,19 +106,30 @@ STATIC const qstr impl_fields[] = {
     #if MICROPY_PERSISTENT_CODE_LOAD
     MP_QSTR__mpy,
     #endif
+    #if MICROPY_PREVIEW_VERSION_2
+    MP_QSTR__v2,
+    #endif
 };
 STATIC MP_DEFINE_ATTRTUPLE(
     mp_sys_implementation_obj,
     impl_fields,
-    3 + MICROPY_PERSISTENT_CODE_LOAD,
-    SYS_IMPLEMENTATION_ELEMS
+    3 + MICROPY_PERSISTENT_CODE_LOAD + MICROPY_PREVIEW_VERSION_2,
+    SYS_IMPLEMENTATION_ELEMS_BASE
+    SYS_IMPLEMENTATION_ELEMS__MPY
+    SYS_IMPLEMENTATION_ELEMS__V2
     );
 #else
 STATIC const mp_rom_obj_tuple_t mp_sys_implementation_obj = {
     {&mp_type_tuple},
     3 + MICROPY_PERSISTENT_CODE_LOAD,
+    // Do not include SYS_IMPLEMENTATION_ELEMS__V2 because
+    // SYS_IMPLEMENTATION_ELEMS__MPY may be empty if
+    // MICROPY_PERSISTENT_CODE_LOAD is disabled, which means they'll share
+    // the same index. Cannot query _v2 if MICROPY_PY_ATTRTUPLE is
+    // disabled.
     {
-        SYS_IMPLEMENTATION_ELEMS
+        SYS_IMPLEMENTATION_ELEMS_BASE
+                                SYS_IMPLEMENTATION_ELEMS__MPY
     }
 };
 #endif

py/mpconfig.h

@@ -53,6 +53,12 @@
 #define MICROPY_VERSION_STRING MICROPY_VERSION_STRING_BASE
 #endif
 
+// If this is enabled, then in-progress/breaking changes slated for the 2.x
+// release will be enabled.
+#ifndef MICROPY_PREVIEW_VERSION_2
+#define MICROPY_PREVIEW_VERSION_2 (0)
+#endif
+
 // This file contains default configuration settings for MicroPython.
 // You can override any of the options below using mpconfigport.h file
 // located in a directory of your port.
@@ -1828,8 +1834,12 @@ typedef double mp_float_t;
 
 // String used for the banner, and sys.version additional information
 #ifndef MICROPY_BANNER_NAME_AND_VERSION
+#if MICROPY_PREVIEW_VERSION_2
+#define MICROPY_BANNER_NAME_AND_VERSION "MicroPython (with v2.0 preview) " MICROPY_GIT_TAG " on " MICROPY_BUILD_DATE
+#else
 #define MICROPY_BANNER_NAME_AND_VERSION "MicroPython " MICROPY_GIT_TAG " on " MICROPY_BUILD_DATE
 #endif
+#endif
 
 // String used for the second part of the banner, and sys.implementation._machine
 #ifndef MICROPY_BANNER_MACHINE

tools/ci.sh

@@ -462,6 +462,15 @@ function ci_unix_standard_run_tests {
     ci_unix_run_tests_full_helper standard
 }
 
+function ci_unix_standard_v2_build {
+    ci_unix_build_helper VARIANT=standard MICROPY_PREVIEW_VERSION_2=1
+    ci_unix_build_ffi_lib_helper gcc
+}
+
+function ci_unix_standard_v2_run_tests {
+    ci_unix_run_tests_full_helper standard
+}
+
 function ci_unix_coverage_setup {
     sudo pip3 install setuptools
     sudo pip3 install pyelftools