Handle both bugged and unbugged __sinit_ behaviors

mwccgap/mwccgap.py

@@ -293,12 +293,14 @@ def replace_sinit(symbol_name, temp_file_name, c_file_name):
     Substitute original file name into MWCC static initializer symbol names
 
     When files contain static initializer code (e.g. static definitions
-    referencing the address of another static variable), MWCC emits the
-    symbols:
-    - `.p__sinit_foo.cpp[...]`
-    - `__sinit_foo.cpp[...]`
-    - `.mwcats___sinit_foo.cpp[...]`
-    where `[...]` is enough space characters to fill the symbol name buffer.
+    referencing the address of another static variable), MWCC emits the symbols:
+    - `.p__sinit_foo.cpp`
+    - `__sinit_foo.cpp`
+    - `.mwcats___sinit_foo.cpp`
+
+    On certain versions of MWCC, the symbol generation code is bugged. When
+    generating the symbol name, the first character is treated as the minimum
+    format width and the filename is right padded.
 
     `.p__sinit_foo.cpp` is a pointer object in the `.ctor` section, with a
     reloc pointing to `__sinit_foo.cpp`. This is linked into a table alongside
@@ -313,10 +315,12 @@ def replace_sinit(symbol_name, temp_file_name, c_file_name):
     using the temporary file's name. We replace it with the original file name
     to operate transparently & enable linking these symbols.
     """
-    # symmetrically ljust to handle both smaller & longer cases
-    old = temp_file_name.ljust(len(c_file_name))
-    new = c_file_name.ljust(len(old))
-    assert len(old) == len(new)
-    fixed_name = symbol_name.replace(old, new)
-    assert fixed_name.find(temp_file_name) == -1
-    return fixed_name
+    prefix, _, symbol_file_name = symbol_name.partition(SYMBOL_SINIT)
+    assert len(symbol_file_name) > 0
+
+    # MWCC bug: filename is padded based on first character of file name
+    if len(symbol_file_name) > len(temp_file_name):
+        assert symbol_file_name == temp_file_name.ljust(ord(temp_file_name[0]))
+        return prefix + SYMBOL_SINIT + c_file_name.ljust(ord(c_file_name[0]))
+
+    return prefix + SYMBOL_SINIT + c_file_name

tests/test_mwccgap.py

@@ -5,25 +5,38 @@
 
 
 class TestSinitSymbolNames(unittest.TestCase):
-    def test_unrelated(self):
-        symbol_name = "some_function"
-        result = replace_sinit(symbol_name, "tmp12234567.c", "test.cpp")
-        self.assertEqual(symbol_name, result)
-
     def test_short_filename(self):
         c_file_name = "short.cpp"
         temp_f_name = "tmp12456789.c"
-        symbol_name = f".p__sinit_{temp_f_name}".ljust(253)
-        expect_name = f".p__sinit_{c_file_name}".ljust(253)
+        symbol_name = f".p__sinit_{temp_f_name}"
+        expect_name = f".p__sinit_{c_file_name}"
 
         result = replace_sinit(symbol_name, temp_f_name, c_file_name)
         self.assertEqual(expect_name, result)
 
     def test_long_filename(self):
         c_file_name = "extra_long_name.cpp"
         temp_f_name = "tmp12456789.c"
-        symbol_name = f"__sinit_{temp_f_name}".ljust(253)
-        expect_name = f"__sinit_{c_file_name}".ljust(253)
+        symbol_name = f"__sinit_{temp_f_name}"
+        expect_name = f"__sinit_{c_file_name}"
+
+        result = replace_sinit(symbol_name, temp_f_name, c_file_name)
+        self.assertEqual(expect_name, result)
+
+    def test_short_filename_bugged_symbols(self):
+        c_file_name = "short.cpp"
+        temp_f_name = "tmp12456789.c"
+        symbol_name = f".p__sinit_{temp_f_name.ljust(ord(temp_f_name[0]))}"
+        expect_name = f".p__sinit_{c_file_name.ljust(ord(c_file_name[0]))}"
+
+        result = replace_sinit(symbol_name, temp_f_name, c_file_name)
+        self.assertEqual(expect_name, result)
+
+    def test_long_filename_bugged_symbols(self):
+        c_file_name = "extra_long_name.cpp"
+        temp_f_name = "tmp12456789.c"
+        symbol_name = f"__sinit_{temp_f_name.ljust(ord(temp_f_name[0]))}"
+        expect_name = f"__sinit_{c_file_name.ljust(ord(c_file_name[0]))}"
 
         result = replace_sinit(symbol_name, temp_f_name, c_file_name)
         self.assertEqual(expect_name, result)