[3.6] bpo-10746: Fix ctypes PEP 3118 type codes for c_long, c_bool, c_int (GH-31) #3241
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…_int (pythonGH-31) Ctypes currently produces wrong pep3118 type codes for several types. E.g. memoryview(ctypes.c_long()).format gives "<l" on 64-bit platforms, but it should be "<q" instead for sizeof(c_long) == 8 The problem is that the '<>' endian specification in the struct syntax also turns on the "standard size" mode, which makes type characters have a platform-independent meaning, which does not match with the codes used internally in ctypes. The struct module format syntax also does not allow specifying native-size non-native-endian items. This commit adds a converter function that maps the internal ctypes codes to appropriate struct module standard-size codes in the pep3118 format strings. The tests are modified to check for this. (cherry picked from commit 07f1658)
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Ctypes currently produces wrong pep3118 type codes for several types.
E.g. memoryview(ctypes.c_long()).format gives "<l" on 64-bit platforms,
but it should be "<q" instead for sizeof(c_long) == 8
The problem is that the '<>' endian specification in the struct syntax
also turns on the "standard size" mode, which makes type characters have
a platform-independent meaning, which does not match with the codes used
internally in ctypes. The struct module format syntax also does not
allow specifying native-size non-native-endian items.
This commit adds a converter function that maps the internal ctypes
codes to appropriate struct module standard-size codes in the pep3118
format strings. The tests are modified to check for this.
(cherry picked from commit 07f1658)
https://bugs.python.org/issue10746