dtlib: add lineno/filename to string representation of a DT

Output lineno/filename as comments in the string representation of a DT
to help with debugging DT issues. Also, remove the added comments when
comparing the string representation of a DT to a reference string in the
DT testsuite.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>
Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

Author: kartben

scripts/dts/python-devicetree/src/devicetree/dtlib.py

@@ -202,13 +202,37 @@ def __str__(self):
         Returns a DTS representation of the node. Called automatically if the
         node is print()ed.
         """
-        s = "".join(label + ": " for label in self.labels)
+        def safe_relpath(filename):
+            # Returns a relative path to the file, or the absolute path if
+            # a relative path cannot be established (on Windows with files
+            # in different drives, for example).
+            try:
+                return os.path.relpath(filename, start=os.getcwd())
+            except ValueError:
+                return filename
+
+        rel_filename = safe_relpath(self.filename)
+        s = f"\n/* node '{self.path}' defined in {rel_filename}:{self.lineno} */\n"
+        s += "".join(label + ": " for label in self.labels)
 
         s += f"{self.name} {{\n"
 
+        lines = []
+        comments = {}
         for prop in self.props.values():
             prop_str = textwrap.indent(str(prop), "\t")
-            s += prop_str + "\n"
+            lines.extend(prop_str.splitlines(True))
+
+            rel_filename = safe_relpath(prop.filename)
+            comment = f"/* in {rel_filename}:{prop.lineno} */"
+            comments[len(lines)-1] = comment
+
+        if lines:
+            max_len = max([ len(line.rstrip()) for line in lines ])
+            for i, line in enumerate(lines):
+                if i in comments:
+                    line += " " * (max_len - len(line) + 1) + comments[i] + "\n"
+                s += line
 
         for child in self.nodes.values():
             s += textwrap.indent(child.__str__(), "\t") + "\n"

scripts/dts/python-devicetree/tests/test_dtlib.py

@@ -26,6 +26,17 @@
 #   - to run a particular test function or functions, use
 #     '-k test_function_pattern_goes_here'
 
+def uncomment(dts):
+    '''Trim added comments from a DT string.'''
+
+    # remove node comments, including leading empty line
+    dts = re.sub(r'\n\n[ \t]*/\*.*?\*/\n', '\n', dts, flags=re.DOTALL)
+
+    # remove property comments
+    dts = re.sub(r'[ \t]*/\*.*?\*/\n', '\n', dts)
+
+    return dts
+
 def parse(dts, include_path=(), **kwargs):
     '''Parse a DTS string 'dts', using the given include path.
 
@@ -48,7 +59,7 @@ def verify_parse(dts, expected, include_path=()):
 
     dt = parse(dts[1:], include_path)
 
-    actual = str(dt)
+    actual = uncomment(str(dt))
     expected = expected[1:-1]
     assert actual == expected, f'unexpected round-trip on {dts}'
 
@@ -1029,7 +1040,7 @@ def test_include_curdir(tmp_path):
 };
 """)
         dt = dtlib.DT("test.dts")
-        assert str(dt) == """
+        assert uncomment(str(dt)) == """
 /dts-v1/;
 
 / {
@@ -1086,7 +1097,7 @@ def test_include_is_lexical(tmp_path):
 	y = < 0x2 >;
 };
 """[1:-1]
-    assert str(dt) == expected_dt
+    assert uncomment(str(dt)) == expected_dt
 
 def test_include_misc(tmp_path):
     '''Miscellaneous /include/ tests.'''