complex but perfectly working grammar

my_grammar<It> grammar;

Test

using grammar direct --> NO ASAN finding

ok = qi::phrase_parse( f, l, qi::eps > grammar > qi::eoi, Skipper{}, v );

using a grammar "wrapper" --> ASAN Finding: stack-use-after-scope

auto grammar_wrapper = qi::eps > grammar > qi::eoi;

ok = qi::phrase_parse( f, l, grammar_wrapper, Skipper{}, v );

i have a problem to understand what type auto grammar_wrapper gets and why this type leads to an stack-user-after-scope

complex but perfectly working grammar

my_grammar<It> grammar;

Test

using grammar direct --> NO ASAN finding

ok = qi::phrase_parse( f, l, qi::eps > grammar > qi::eoi, Skipper{}, v );

using a grammar "wrapper" --> ASAN Finding: stack-use-after-scope

auto grammar_wrapper = qi::eps > grammar > qi::eoi;

ok = qi::phrase_parse( f, l, grammar_wrapper, Skipper{}, v );

i have a problem to understand what type auto grammar_wrapper gets and why this type leads to an stack-user-after-scope

• boost-spirit-qi

1 Answer 1

So... don't use the auto keyword.

If you must, combat dangling references by doing a boost::proto::deep_copy of the parser expressions involved. There's a convenient short-hand in recent versions of Spirit Qi: qi::copy:

auto grammar_wrapper = qi::copy ( qi::eps > grammar > qi::eoi );

Background:

• Assigning parsers to auto variables
• boost spirit V2 qi bug associated with optimization level
• spirit::qi: Combining parser_factory fails
• Boost Spirit Qi crashes for memory violation