TST: added test for issue #3425

numpy/f2py/capi_maps.py

@@ -295,6 +295,20 @@ def getctype(var):
     return ctype
 
 
+def f2cexpr(expr):
+    """Rewrite Fortran expression as f2py supported C expression.
+
+    Due to the lack of proper expression parser in f2py, this function
+    uses heuristic approach that assumes that Fortran arithmetic
+    expressions are often valid C arithmetic expressions when mapping
+    Fortran function calls to the corresponding C function/CPP macros
+    calls.
+    """
+    # TODO: support Fortran `len` function with optional kind parameter
+    expr = re.sub(r'\blen\b', 'f2py_slen', expr)
+    return expr
+
+
 def getstrlength(var):
     if isstringfunction(var):
         if 'result' in var:
@@ -314,7 +328,7 @@ def getstrlength(var):
         if '*' in a:
             len = a['*']
         elif 'len' in a:
-            len = a['len']
+            len = f2cexpr(a['len'])
     if re.match(r'\(\s*(\*|:)\s*\)', len) or re.match(r'(\*|:)', len):
         if isintent_hide(var):
             errmess('getstrlength:intent(hide): expected a string with defined length but got: %s\n' % (

numpy/f2py/tests/test_character.py

@@ -433,11 +433,11 @@ class TestMiscCharacter(util.F2PyTest):
        end subroutine {fprefix}_gh18684
 
        subroutine {fprefix}_gh6308(x, i)
-       integer i
-       !f2py check(i>=0 && i<12) i
-       character*5 name, x
-       common name(12)
-       name(i + 1) = x
+         integer i
+         !f2py check(i>=0 && i<12) i
+         character*5 name, x
+         common name(12)
+         name(i + 1) = x
        end subroutine {fprefix}_gh6308
 
        subroutine {fprefix}_gh4519(x)
@@ -448,6 +448,21 @@ class TestMiscCharacter(util.F2PyTest):
            print*, "x(",i,")=", x(i)
          end do
        end subroutine {fprefix}_gh4519
+
+       pure function {fprefix}_gh3425(x) result (y)
+         character(len=*), intent(in) :: x
+         character(len=len(x)) :: y
+         integer :: i
+         do i = 1, len(x)
+           j = iachar(x(i:i))
+           if (j>=iachar("a") .and. j<=iachar("z") ) then
+             y(i:i) = achar(j-32)
+           else
+             y(i:i) = x(i:i)
+           endif
+         end do
+       end function {fprefix}_gh3425
+
     """)
 
     def test_gh18684(self):
@@ -484,3 +499,12 @@ def test_gh4519(self):
             r = f(x)
             for k, v in expected.items():
                 assert_equal(getattr(r, k), v)
+
+    def test_gh3425(self):
+        # Test returning a copy of assumed length string
+        f = getattr(self.module, self.fprefix + '_gh3425')
+        # f is equivalent to bytes.upper
+
+        assert_equal(f('abC'), b'ABC')
+        assert_equal(f(''), b'')
+        assert_equal(f('abC12d'), b'ABC12D')