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docs/markdown/snippets/consistent_file_locations.md

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+## Consistently report file locations relative to cwd
+
+The paths for filenames in error and warning locations are now consistently
+reported relative to the current working directory (when possible), or as
+absolute paths (when a relative path does not exist, e.g. a Windows path
+starting with a different drive letter to the current working directory).
+
+(The previous behaviour was to report a path relative to the source root for all
+warnings and most errors, and relative to cwd for certain parser errors)