numba 0.55 breaks compatibility with coverage

Reporting a bug

• I have tried using the latest released version of Numba (most recent is visible in the change log (https://github.com/numba/numba/blob/master/CHANGE_LOG).
• I have included a self contained code sample to reproduce the problem. i.e. it’s possible to run as ‘python bug.py’.

Since numba 0.55 python files importing numba are causing trouble in combination with coverage xml.

Example

“example.py”:

from numba import jit
import numpy as np


@jit(nopython=True) # Set "nopython" mode for best performance, equivalent to @njit
def go_fast(a):
    trace = 0.0
    for i in range(a.shape[0]):
        trace += np.tanh(a[i, i])
    return a + trace

def main():
    x = np.arange(100).reshape(10, 10)
    print(go_fast(x))


if __name__ == '__main__':
    main()

Expected behavior (as with numba 0.54)

$ python -m coverage run example.py
[[  9.  10.  11.  12.  13.  14.  15.  16.  17.  18.]
 [ 19.  20.  21.  22.  23.  24.  25.  26.  27.  28.]
 [ 29.  30.  31.  32.  33.  34.  35.  36.  37.  38.]
 [ 39.  40.  41.  42.  43.  44.  45.  46.  47.  48.]
 [ 49.  50.  51.  52.  53.  54.  55.  56.  57.  58.]
 [ 59.  60.  61.  62.  63.  64.  65.  66.  67.  68.]
 [ 69.  70.  71.  72.  73.  74.  75.  76.  77.  78.]
 [ 79.  80.  81.  82.  83.  84.  85.  86.  87.  88.]
 [ 89.  90.  91.  92.  93.  94.  95.  96.  97.  98.]
 [ 99. 100. 101. 102. 103. 104. 105. 106. 107. 108.]]
$ python -m coverage xml
Wrote XML report to coverage.xml

Found

$ python -m coverage run example.py
[[  9.  10.  11.  12.  13.  14.  15.  16.  17.  18.]
 [ 19.  20.  21.  22.  23.  24.  25.  26.  27.  28.]
 [ 29.  30.  31.  32.  33.  34.  35.  36.  37.  38.]
 [ 39.  40.  41.  42.  43.  44.  45.  46.  47.  48.]
 [ 49.  50.  51.  52.  53.  54.  55.  56.  57.  58.]
 [ 59.  60.  61.  62.  63.  64.  65.  66.  67.  68.]
 [ 69.  70.  71.  72.  73.  74.  75.  76.  77.  78.]
 [ 79.  80.  81.  82.  83.  84.  85.  86.  87.  88.]
 [ 89.  90.  91.  92.  93.  94.  95.  96.  97.  98.]
 [ 99. 100. 101. 102. 103. 104. 105. 106. 107. 108.]]
$ python -m coverage xml
No source for code: '/path/to/working/directory/__numba_array_expr_synthetic_module_example.py'.

coverage version is 6.2.

Many thanks for looking into this.
Best, Emanuel

[emanuel-schmid]

Sure, fully aware of that. It’s the effort that’s valued. 😃

[gmarkall]

Applying:

diff --git a/numba/np/ufunc/array_exprs.py b/numba/np/ufunc/array_exprs.py
index 3fe85ba5e..bb8815ddc 100644
--- a/numba/np/ufunc/array_exprs.py
+++ b/numba/np/ufunc/array_exprs.py
@@ -333,7 +333,7 @@ def _lower_array_expr(lowerer, expr):
     '''Lower an array expression built by RewriteArrayExprs.
     '''
     expr_name = "__numba_array_expr_%s" % (hex(hash(expr)).replace("-", "_"))
-    expr_filename = f"__numba_array_expr_synthetic_module_{expr.loc.filename}"
+    expr_filename = expr.loc.filename
     expr_var_list = expr.list_vars()
     # The expression may use a given variable several times, but we
     # should only create one parameter for it.

appears to resolve this issue, and doesn’t introduce any failures in any of the tests added or modified in #7177.