[core] Support string views and C strings in Join - #23392
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Shubham-Padkonde wants to merge 2 commits into
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Shubham-Padkonde wants to merge 2 commits into
Shubham-Padkonde wants to merge 2 commits into
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pcanal
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Sep 16, 2026
| return ""; | ||
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| return std::accumulate(std::next(begin), end, *begin, [&sep](auto const &a, auto const &b) { return a + sep + b; }); | ||
| std::string result(*begin++); |
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Isn't there a working version using std::accumulate rather than an explicit for loop?
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ROOT::Joincannot compile when its input is a container ofstd::string_viewor an array of C strings.std::accumulateinfers the accumulator type from the input element, and the concatenation assumes owning strings.Build the result in an owning
std::stringand append each element and separator. This also avoids repeatedly copying the entire accumulated prefix. Existing empty-string and separator behavior is preserved.Add coverage for non-null-terminated string views, the iterator overload, and a C-string array containing an empty element.
Validation: the new tests fail to compile on the original implementation. All six StringUtils tests pass with the fix, built directly with GCC 13, C++17,
-Wall -Wextra -Werror, and GoogleTest. Changed lines were formatted with the repository clang-format configuration. Full ROOT build and CI were not run locally.AI disclosure: Codex prepared the implementation, tests, and description. The contributor must review and understand the patch before submitting, as required by ROOT's contribution policy.