Fix incorrect warning when converting to CFF a CFF2 variable font with non-varying glyphs

Tests/runner.py

@@ -17,7 +17,7 @@
 import sys
 import tempfile
 
-__version__ = '0.4.0'
+__version__ = '0.5.0'
 
 logger = logging.getLogger('runner')
 
@@ -54,7 +54,7 @@ def run_tool(opts):
     """
     input_dir = _get_input_dir_path(opts.tool)
 
-    args = []
+    args = [opts.tool]
     for opt in opts.options:
         if opt.startswith('='):
             args.append('--{}'.format(opt[1:]))
@@ -65,8 +65,6 @@ def run_tool(opts):
         else:
             args.append('-{}'.format(opt))
 
-    args.insert(0, opts.tool)
-
     if opts.files:
         if opts.abs_paths:
             files = opts.files
@@ -80,13 +78,18 @@ def run_tool(opts):
         save_loc = _get_save_location(opts.save_path)
         args.append(save_loc)
 
+    stderr = None
+    if opts.std_error:
+        stderr = subprocess.STDOUT
+
     logger.debug(
         "About to run the command below\n==>{}<==".format(' '.join(args)))
     try:
         if opts.no_save_path:
             return subprocess.check_call(args, timeout=TIMEOUT)
         else:
-            output = subprocess.check_output(args, timeout=TIMEOUT)
+            output = subprocess.check_output(args, stderr=stderr,
+                                             timeout=TIMEOUT)
             if opts.redirect:
                 _write_file(save_loc, output)
             return save_loc
@@ -197,6 +200,12 @@ def get_options(args):
         action='store_true',
         help="redirect the tool's output to a file"
     )
+    parser.add_argument(
+        '-e',
+        '--std-error',
+        action='store_true',
+        help="capture stderr instead of stdout"
+    )
     save_parser = parser.add_mutually_exclusive_group()
     save_parser.add_argument(
         '-s',

Tests/tx_test.py

@@ -206,3 +206,14 @@ def test_many_hints_string_bug354():
     dcf_txt_path = runner(CMD + ['-a', '-f', cff2_path, '-o', 'dcf'])
     expected_path = _get_expected_path('cff2_vf.dcf.txt')
     assert differ([expected_path, dcf_txt_path])
+
+
+def test_non_varying_glyphs_bug356():
+    """A glyph which is non-varying in a variable font may be referenced by a
+    VariationStore data item subtable which has a region count of 0. The VF
+    support code assumed that this was an error, and issued a false warning.
+    File 'bug356.otf' is a handcrafted modification of 'cff2_vf.otf'. The
+    latter cannot be used as-is to validate the fix."""
+    stderr_path = runner(CMD + ['-r', '-e', '-o', 'cff', '-f', 'bug356.otf'])
+    expected_path = _get_expected_path('bug356.txt')
+    assert differ([expected_path, stderr_path, '-l', '1'])

afdko/Tools/Programs/public/lib/source/varread/varread.c

@@ -986,6 +986,14 @@ static float var_applyDeltasForIndexPair(ctlSharedStmCallbacks *sscb, var_itemVa
     }
 
     subtable = &dataList->ivdSubtables.array[pair->outerIndex];
+
+    /* If specific glyphs do not have any variation, they may be
+     referenced by an ivdSubtable with a region count of 0. This is
+     valid.
+     */
+    if (subtable->regionCount == 0) 
+        return netAdjustment;
+
     if (subtable->regionCount > regionListCount) {
         sscb->message(sscb, "out of range region count in item variation store subtable");
         return netAdjustment;