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Fix compilation failure from regex source generator with some lazy loops #118132

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Merged
merged 1 commit into from
Jul 28, 2025
Merged

Fix compilation failure from regex source generator with some lazy loops #118132

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3 changes: 2 additions & 1 deletion src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.Emitter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3743,7 +3743,8 @@ void EmitLazy(RegexNode node)
{
startingPos = ReserveName("lazyloop_starting_pos");
sawEmpty = ReserveName("lazyloop_empty_seen");
writer.WriteLine($"int {startingPos} = pos, {sawEmpty} = 0; // the lazy loop may match empty iterations");
additionalDeclarations.Add($"int {startingPos} = 0, {sawEmpty} = 0;");
writer.WriteLine($"{startingPos} = {sawEmpty} = 0; // the lazy loop may match empty iterations");
}

// If the min count is 0, start out by jumping right to what's after the loop. Backtracking
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8 changes: 8 additions & 0 deletions src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Match.Tests.cs
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Expand Up @@ -277,6 +277,14 @@ public static IEnumerable<object[]> Match_MemberData()
yield return (@"(abcd*?)+e", "abcde", RegexOptions.None, 0, 5, true, "abcde");
yield return (@"(abcd*)+?e", "abcde", RegexOptions.None, 0, 5, true, "abcde");
yield return (@"(abcd*?)+?e", "abcde", RegexOptions.None, 0, 5, true, "abcde");
yield return (@"(?:m(?:((e)?)??)|a)\b", "you m you", RegexOptions.None, 0, 9, true, "m");
yield return (@"(?:m(?:((e)?)??)|a)\b", "you me you", RegexOptions.None, 0, 10, true, "me");
yield return (@"(?:m(?:((e)?)??)|a)\b", "you a you", RegexOptions.None, 0, 9, true, "a");
yield return (@"(?:m(?:((e)?)??)|a)\b", "you and you", RegexOptions.None, 0, 11, false, "");
yield return (@"(?:m(?:|(e)?)|a)\b", "you m you", RegexOptions.None, 0, 9, true, "m");
yield return (@"(?:m(?:|(e)?)|a)\b", "you me you", RegexOptions.None, 0, 10, true, "me");
yield return (@"(?:m(?:|(e)?)|a)\b", "you a you", RegexOptions.None, 0, 9, true, "a");
yield return (@"(?:m(?:|(e)?)|a)\b", "you and you", RegexOptions.None, 0, 11, false, "");

// Testing selected FindOptimizations finds the right prefix
yield return (@"(^|a+)bc", " aabc", RegexOptions.None, 0, 5, true, "aabc");
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