[llvm] [Dexter] Add label nodes for line references (PR #202544)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -66,17 +112,49 @@ def add_where(self, where: Where):
         """Adds `where` to this Scope's chain."""
         return Scope(where=where, parent_scope=self)
 
+    def get_known_file_for_where(self, where: Where) -> Optional[str]:
+        """For a `where` that exists directly in this Scope, determines whether there is a known file that `where`
+        expects - whether this is an explicitly-declared file, or implicitly the root scope file. There is no known file
+        for !where {function: ...} nodes, however."""
+        if where.file:
+            return where.file
+        if where.function:
+            return None
+        next_scope = self
+        while where.is_and:
+            assert (
+                next_scope.parent_scope and next_scope.where
+            ), "!and node at root scope?"
+            where = next_scope.where
+            if where.file:
+                return where.file
+            if where.function:
+                return None
+            next_scope = next_scope.parent_scope
+        while next_scope.file is None:
+            assert next_scope.parent_scope
+            next_scope = next_scope.parent_scope
+        return next_scope.file
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OCHyams wrote:

Is it possible for the "root scope" be a `!where {function: ...}` (thus presumably hitting the assert)?

https://github.com/llvm/llvm-project/pull/202544