The following worked in v2.063.2, but not in the latest github masters (This is preventing the "ddemangle" tool from compiling in the latest github master):

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import core.demangle;
import std.regex;
void main()
{
    replace!((a) => demangle(a.hit))("blah", regex(`a`));
}
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Result with github master:

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../dmd/src/../../phobos/std/regex.d(6078): Error: template D main.__lambda2 does not match any function template declaration. Candidates are:
test.d(5):        test.main.__lambda2(__T1)(a)
../dmd/src/../../phobos/std/regex.d(6078): Error: template test.main.__lambda2(__T1)(a) cannot deduce template function from argument types !()(Captures!(string, uint), Appender!string)
../dmd/src/../../phobos/std/regex.d(6106): Error: template instance test.main.replaceMatchesInto!(__lambda2, Appender!string, string, RegexMatch!(string, ThompsonMatcher)) error instantiating
../dmd/src/../../phobos/std/regex.d(6399):        instantiated from here: replaceAllWith!(__lambda2, match, string, Regex!char)
test.d(5):        instantiated from here: replace!(__lambda2, string, Regex!char)
../dmd/src/../../phobos/std/regex.d(6399): Error: template instance test.main.replaceAllWith!(__lambda2, match, string, Regex!char) error instantiating
test.d(5):        instantiated from here: replace!(__lambda2, string, Regex!char)
test.d(5): Error: template instance test.main.replace!(__lambda2, string, Regex!char) error instantiating
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