py/parse: Add support for math module constants and float folding.

Add a new MICROPY_COMP_CONST_FLOAT feature, enabled by in mpy-cross and
when compiling with MICROPY_CONFIG_ROM_LEVEL_CORE_FEATURES.  The new
feature leverages the code of MICROPY_COMP_CONST_FOLDING to support folding
of floating point constants.

If MICROPY_COMP_MODULE_CONST is defined as well, math module constants are
made available at compile time. For example:

    _DEG_TO_GRADIANT = const(math.pi / 180)
    _INVALID_VALUE = const(math.nan)

A few corner cases had to be handled:
- The float const folding code should not fold expressions resulting into
  complex results, as the mpy parser for complex immediates has
  limitations.
- The constant generation code must distinguish between -0.0 and 0.0, which
  are different even if C consider them as ==.

This change removes previous limitations on the use of `const()`
expressions that would result in floating point number, so the test cases
of micropython/const_error have to be updated.

Additional test cases have been added to cover the new repr() code (from a
previous commit).  A few other simple test cases have been added to handle
the use of floats in `const()` expressions, but the float folding code
itself is also tested when running general float test cases, as float
expressions often get resolved at compile-time (with this change).

Signed-off-by: Yoctopuce dev <dev@yoctopuce.com>

1 files changed, 0 insertions, 2 deletions

diff --git a/tests/micropython/const_error.py b/tests/micropython/const_error.py
index d35be530a..950360e4d 100644
--- a/tests/micropython/const_error.py
+++ b/tests/micropython/const_error.py
@@ -18,8 +18,6 @@ test_syntax("A = const(1); A = const(2)")
 
 # these operations are not supported within const
 test_syntax("A = const(1 @ 2)")
-test_syntax("A = const(1 / 2)")
-test_syntax("A = const(1 ** -2)")
 test_syntax("A = const(1 << -2)")
 test_syntax("A = const(1 >> -2)")
 test_syntax("A = const(1 % 0)")