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934127cca5
Adds two source span utility functions used in source-based coverage `span.is_empty()` - returns true if `lo()` and `hi()` are equal. This is not only a convenience, but makes it clear that a `Span` can be empty (that is, retrieving the source for an empty `Span` will return an empty string), and codifies the (otherwise undocumented--in the rustc_span package, at least) fact that `Span` is a half-open interval (where `hi()` is the open end). `source_map.lookup_file_span()` - returns an enclosing `Span` representing the start and end positions of the file enclosing the given `BytePos`. This gives developers a clear way to quickly determine if any any other `BytePos` or `Span` is also from the same file (for example, by simply calling `file_span.contains(span)`). This results in much simpler code and is much more runtime efficient compared with the obvious alternative: calling `source_map.lookup_line()` for any two `Span`'s byte positions, handle both arms of the `Result` (both contain the file), and then compare files. It is also more efficient than the non-public method `lookup_source_file_idx()` for each `BytePos`, because, while comparing the internal source file indexes would be efficient, looking up the source file index for every `BytePos` or `Span` to be compared requires a binary search (worst case performance being O(log n) for every lookup). `source_map.lookup_file_span()` performs the binary search only once, to get the `file_span` result that can be used to compare to any number of other `BytePos` or `Span` values and those comparisons are always O(1). This PR was split out from PR #75828 . r? @tmandry FYI: @wesleywiser |
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| .. | ||
| rustc | ||
| rustc_apfloat | ||
| rustc_arena | ||
| rustc_ast | ||
| rustc_ast_lowering | ||
| rustc_ast_passes | ||
| rustc_ast_pretty | ||
| rustc_attr | ||
| rustc_builtin_macros | ||
| rustc_codegen_llvm | ||
| rustc_codegen_ssa | ||
| rustc_data_structures | ||
| rustc_driver | ||
| rustc_error_codes | ||
| rustc_errors | ||
| rustc_expand | ||
| rustc_feature | ||
| rustc_fs_util | ||
| rustc_graphviz | ||
| rustc_hir | ||
| rustc_hir_pretty | ||
| rustc_incremental | ||
| rustc_index | ||
| rustc_infer | ||
| rustc_interface | ||
| rustc_lexer | ||
| rustc_lint | ||
| rustc_macros | ||
| rustc_metadata | ||
| rustc_middle | ||
| rustc_mir | ||
| rustc_mir_build | ||
| rustc_parse | ||
| rustc_parse_format | ||
| rustc_passes | ||
| rustc_plugin_impl | ||
| rustc_privacy | ||
| rustc_query_system | ||
| rustc_resolve | ||
| rustc_save_analysis | ||
| rustc_serialize | ||
| rustc_session | ||
| rustc_span | ||
| rustc_symbol_mangling | ||
| rustc_target | ||
| rustc_trait_selection | ||
| rustc_traits | ||
| rustc_ty | ||
| rustc_typeck | ||