verilog: fix string literal regular expression #5187
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A backslash was improperly quoted, causing string literal matching to fail when the final token before a closing quote was an escaped backslash.
zachjs
approved these changes
Jun 19, 2025
|
While fixing this, I also noticed another bug related to escape sequences in string literals: yosys doesn't seem to process escaped newlines (as in string literal split over multiple lines, not the "\n" sequence) according to IEEE 1800-2012 sec 5.9. (It looks like such strings are accepted, but the resulting value can be wrong.) However, since that bug predates the recent changes, I'll plan to submit a new PR once I have time to investigate. |
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What are the reasons/motivation for this change?
Fix the bug reported in #5160, where a closing quote on a string literal failed to terminate the string when preceded by an escaped backslash.
Originally posted by @mmicko in #5160 (comment)
Explain how this is achieved.
Properly escape the backslash in the regular expression in
verilog_lexer.l.If applicable, please suggest to reviewers how they can test the change.
See the included regression test
tests/verilog/bug5160.v, or @mmicko's test case in the original report.With this fix applied, both cases work properly. Before the fix, parsing would fail with a spurious syntax error.