Even for things where the nesting does happen during lexical analysis, it's pretty trivial to keep a count in your lexer. Lots of languages support nesting comment syntax or string interpolation, which both have equivalent difficulty.
To use formal language theory, strings containing escape characters are regular, i.e. parseable with a finite-state machine. Allowing nesting means you need a stack to find the matching pair.
/* nested /* comments */ don't work */ (* nested (* comments *) work *)https://wiki.dlang.org/Commenting_out_code#Nested_comments
This allows commenting out code containing comments, which can be useful when debugging or giving usage examples in the code.
«Oh, you just use the « character.»
Parse error. Unexpected EOF.
To clarify: we’d still need escaping but in fewer cases.
To end a string, use the » character.
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