make test fails on Cygwin (git head)

[versat]

[FIXED] (see reply)

I never had problems with make test under Cygwin and it worked just some days ago.
But now it suddenly fails and i have no idea why.
I am using git head (8e6ac60797c43a1df1fbcae31d1012cc57158b5f).
Testrunner works with the Visual Studio build (same working directory) and i can run make test successfully on Ubuntu 16.04.
Here is the error output:

Testing Complete
Number of tests: 3145
Number of todos: 207
Tests failed: 18

test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\AssignmentAddressToInteger\bad.c:3]: (portability) Assigning a pointer to an integer is not portable.\n

Actual: 
[samples\AssignmentAddressToInteger\bad.c:3]: (portability) Assigning a pointer to an integer is not portable.\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/AssignmentAddressToInteger/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/AssignmentAddressToInteger/good.c
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\arrayIndexOutOfBounds\bad.c:6]: (error) Array 'a[2]' accessed at index 2, which is out of bounds.\n

Actual: 
[samples\arrayIndexOutOfBounds\bad.c:6]: (error) Array 'a[2]' accessed at index 2, which is out of bounds.\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/arrayIndexOutOfBounds/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/arrayIndexOutOfBounds/good.c
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\autoVariables\bad.c:4]: (error) Address of local auto-variable assigned to a function parameter.\n

Actual: 
[samples\autoVariables\bad.c:4]: (error) Address of local auto-variable assigned to a function parameter.\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/autoVariables/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/autoVariables/good.c
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\bufferAccessOutOfBounds\bad.c:6]: (error) Array 'a[2]' accessed at index 2, which is out of bounds.\n

Actual: 
[samples\bufferAccessOutOfBounds\bad.c:6]: (error) Array 'a[2]' accessed at index 2, which is out of bounds.\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/bufferAccessOutOfBounds/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/bufferAccessOutOfBounds/good.c
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\erase\bad.cpp:9] -> [samples\erase\bad.cpp:11]: (error) Iterator 'iter' used after element has been erased.\n

Actual: 
[samples\erase\bad.cpp:9] -> [samples\erase\bad.cpp:11]: (error) Iterator 'iter' used after element has been erased.\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/erase/bad.cpp
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/erase/good.cpp
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\memleak\bad.c:8]: (error) Memory leak: a\n

Actual: 
[samples\memleak\bad.c:8]: (error) Memory leak: a\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/memleak/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/memleak/good.c
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\outOfBounds\bad.c:5]: (error) Buffer is accessed out of bounds: str\n

Actual: 
[samples\outOfBounds\bad.c:5]: (error) Buffer is accessed out of bounds: str\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/outOfBounds/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/outOfBounds/good.c
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\resourceLeak\bad.c:8]: (error) Resource leak: a\n

Actual: 
[samples\resourceLeak\bad.c:8]: (error) Resource leak: a\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/resourceLeak/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/resourceLeak/good.c
_____
test/testsamples.cpp:91: Assertion failed. 
Expected: 
[samples\syntaxError\bad.c:2]: (error) Invalid number of character '{' when no macros are defined.\n

Actual: 
[samples\syntaxError\bad.c:2]: (error) Invalid number of character '{' when no macros are defined.\n
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/syntaxError/bad.c
_____
test/testsamples.cpp:79: Assertion failed. 
Expected: 

Actual: 
[test.cpp:1]: (style) The function 'f' is never used.\n

Hint:
samples/syntaxError/good.c
_____
make: *** [Makefile:260: test] Error 1

There are unexpected unused function warnings. But i wonder why this only happens with Cygwin.
Any idea?
Versions:
Cygwin: g++ 6.4.0
Ubuntu 16.04: g++ 5.4.0
Visual Studio: 11 Update 5

[versat]

Fixed by commit https://github.com/danmar/cppcheck/commit/db274e830865c99be1a4d0709b16018f9951d140
Thanks amai and danmar.