[utils] only use column for comparison when emitted

This fixes a bug that was introduced where two diagnostics on the same
line, with the same content, would be emitted separately if they
occurred on separate columns. This despite the fact that neither of
these checks specify the column when emitted. The checks are now
properly merged again.

Author: hnrklssn

utils/update_verify_tests/core.py

@@ -82,7 +82,7 @@ def __init__(
         self.absolute_target()
         self.whitespace_strings = whitespace_strings
         self.is_from_source_file = is_from_source_file
-        self.col = col
+        self._col = col
         self.nested_lines = nested_lines
         self.parent = None
         self.closer = None
@@ -116,6 +116,12 @@ def absolute_target(self):
     def relative_target(self):
         return self.absolute_target() - self.line.line_n
 
+    def col(self):
+        # expected-expansion requires column. Otherwise only retain column info if it's already there.
+        if self._col and (self.category == "expansion" or self.is_from_source_file):
+            return self._col
+        return None
+
     def take(self, other_diag):
         assert self.count == 0
         assert other_diag.count > 0
@@ -159,11 +165,7 @@ def render(self):
             standard single space, let it be to avoid disrupting manual formatting.
             """
             whitespace2_s = ""
-        col_s = (
-            f":{self.col}"
-            if self.col and (self.category == "expansion" or self.is_from_source_file)
-            else ""
-        )
+        col_s = f":{self.col()}" if self.col() else ""
         base_s = f"//{whitespace1_s}expected-{self.prefix}{self.category}{re_s}{line_location_s}{col_s}{whitespace2_s}{count_s}"
         if self.category == "expansion":
             return base_s + "{{"
@@ -438,7 +440,7 @@ def expand_expansions(lines):
 
 
 def error_refers_to_diag(diag_error, diag, target_line_n):
-    if diag_error.col and diag.col and diag_error.col != diag.col:
+    if diag_error.col and diag.col() and diag_error.col != diag.col():
         return False
     return (
         target_line_n == diag.absolute_target()