Fix rendering for numpy scalars

In numpy 2.0, `repr(np.float64(0.5))` is `"np.float64(0.5)"`. Before, it was `"0.5"` (as for a Python `float`).

brian2/parsing/rendering.py

@@ -1,6 +1,7 @@
 import ast
 import numbers
 
+import numpy as np
 import sympy
 
 from brian2.core.functions import DEFAULT_CONSTANTS, DEFAULT_FUNCTIONS
@@ -87,6 +88,9 @@ def render_Name(self, node):
         return node.id
 
     def render_Constant(self, node):
+        if isinstance(node.value, np.number):
+            # repr prints the dtype in numpy 2.0
+            return repr(node.value.item())
         return repr(node.value)
 
     def render_Call(self, node):
@@ -344,7 +348,7 @@ def render_Constant(self, node):
         elif node.value is False:
             return "false"
         else:
-            return repr(node.value)
+            return super().render_Constant(node)
 
     def render_Name(self, node):
         if node.id == "inf":

brian2/tests/test_codegen.py

@@ -10,6 +10,7 @@
 from brian2 import _cache_dirs_and_extensions, clear_cache, prefs
 from brian2.codegen.codeobject import CodeObject
 from brian2.codegen.cpp_prefs import compiler_supports_c99, get_compiler_and_args
+from brian2.codegen.generators.cython_generator import CythonNodeRenderer
 from brian2.codegen.optimisation import optimise_statements
 from brian2.codegen.runtime.cython_rt import CythonCodeObject
 from brian2.codegen.statements import Statement
@@ -22,6 +23,7 @@
 from brian2.core.functions import DEFAULT_CONSTANTS, DEFAULT_FUNCTIONS, Function
 from brian2.core.variables import ArrayVariable, Constant, Subexpression, Variable
 from brian2.devices.device import auto_target, device
+from brian2.parsing.rendering import CPPNodeRenderer, NodeRenderer, NumpyNodeRenderer
 from brian2.parsing.sympytools import str_to_sympy, sympy_to_str
 from brian2.units import ms, second
 from brian2.units.fundamentalunits import Unit
@@ -618,6 +620,25 @@ def test_msvc_flags():
     assert len(previously_stored_flags[hostname])
 
 
+@pytest.mark.codegen_independent
+@pytest.mark.parametrize(
+    "renderer",
+    [
+        NodeRenderer(),
+        NumpyNodeRenderer(),
+        CythonNodeRenderer(),
+        CPPNodeRenderer(),
+    ],
+)
+def test_number_rendering(renderer):
+    import ast
+
+    for number in [0.5, np.float32(0.5), np.float64(0.5)]:
+        # In numpy 2.0, repr(np.float64(0.5)) is 'np.float64(0.5)'
+        node = ast.Constant(value=number)
+        assert renderer.render_node(node) == "0.5"
+
+
 if __name__ == "__main__":
     test_auto_target()
     test_analyse_identifiers()