https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105720
Bug ID: 105720
Summary: std::views::split_view wrong behaviour in case of
partial match
Product: gcc
Version: 10.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: andij.cr at gmail dot com
Target Milestone: ---
compiled with
g++-10 -std=c++20 split_view_wrong.cpp -lfmt
godbolt link https://gcc.godbolt.org/z/47TxWovd4
fmtlib used for exposition only
#include <fmt/printf.h>
#include <fmt/ranges.h>
#include <ranges>
#include <string_view>
auto words_no_bug = std::string_view{"Hello-_-C++-_-20-_-!-_-"};
auto words_bug = std::string_view{"Hello--_-C++-_-20-_-!-_-"};
auto delim = std::string_view{"-_-"};
// needed because split_view is lazy in gcc 10.3
auto range_to_str = [](auto &&r) {
return fmt::format("{}", fmt::join(r, ""));
};
int main() {
fmt::print("no bug: '{}' tokens: {}\n", words_no_bug,
words_no_bug | std::views::split(delim) |
std::views::transform(range_to_str));
fmt::print("bug: '{}' tokens: {}\n", words_bug,
words_bug | std::views::split(delim) |
std::views::transform(range_to_str));
}
this code applies split to tokenize a text
compiled with gcc-10.3 it wrongly produces
no bug: 'Hello-_-C++-_-20-_-!-_-' tokens: ["Hello", "C++", "20", "!"]
bug: 'Hello--_-C++-_-20-_-!-_-' tokens: ["Hello-", "20", "!"]
while compiled with gcc-11.3 is correctly produces
no bug: 'Hello-_-C++-_-20-_-!-_-' tokens: ["Hello", "C++", "20", "!"]
bug: 'Hello--_-C++-_-20-_-!-_-' tokens: ["Hello-", "C++", "20", "!"]
notice how the substring "--_-C++" instead of being split in ["-", "C++"]
is split as ["-"], skipping the "C++" token.
it's fixed from gcc-11, but i couldn't find a mention in the release notes
about it
