When variant are enabled, the yylhs variable (the left-hand side of the rule being reduced, i.e. $$ and @$) is explicitly destroyed when YYERROR is called. This is because before running the user code, $$ is initialized, so that the user can properly use it.
However, when quitting yyparse, yylhs is also reclaimed by the C++ compiler: the variable goes out of scope. This was not detected by the test suite because (i) the Object tracker was too weak, and (ii) the problem does not show when there is error recovery. Reported by Paolo Simone Gasparello. <http://lists.gnu.org/archive/html/bug-bison/2013-10/msg00003.html> * tests/c++.at (Exception safety): Improve the objects logger to make sure that we never destroy twice an object. Also track copy-constructors. Use a set instead of a list. Display the logs before running the function body, this is more useful in case of failure. Generalize to track with and without error recovery. --- THANKS | 1 + tests/c++.at | 58 +++++++++++++++++++++++++++++++++++++--------------------- 2 files changed, 38 insertions(+), 21 deletions(-) diff --git a/THANKS b/THANKS index 9b7a896..ebadb44 100644 --- a/THANKS +++ b/THANKS @@ -96,6 +96,7 @@ Odd Arild Olsen [email protected] Oleg Smolsky [email protected] Oleksii Taran [email protected] Paolo Bonzini [email protected] +Paolo Simone Gasparello [email protected] Pascal Bart [email protected] Paul Eggert [email protected] Paul Hilfinger [email protected] diff --git a/tests/c++.at b/tests/c++.at index 14a001a..355e624 100644 --- a/tests/c++.at +++ b/tests/c++.at @@ -649,14 +649,18 @@ AT_CLEANUP ## Exception safety. ## ## ------------------ ## -# AT_TEST([BISON-DIRECTIVES]) -# --------------------------- +# AT_TEST([BISON-DIRECTIVES = ''], [WITH-RECOVERY = "with"]) +# ---------------------------------------------------------- # Check that no object is leaked when exceptions are thrown. +# WITH-RECOVERY = "with" or "without". m4_pushdef([AT_TEST], -[AT_SETUP([[Exception safety $1]]) +[AT_SETUP([[Exception safety $2 error recovery $1]]) AT_SKIP_IF_EXCEPTION_SUPPORT_IS_POOR +m4_if([$1], [], [], + [m4_if([$2], [without], [AT_XFAIL_IF([true])])]) + AT_BISON_OPTION_PUSHDEFS([%skeleton "lalr1.cc" $1]) AT_DATA_GRAMMAR([[input.yy]], @@ -669,43 +673,53 @@ $1 #include <cassert> #include <cstdlib> // size_t and getenv. #include <iostream> - #include <list> + #include <set> bool debug = false; - /// A class that counts its number of instances. + /// A class that tracks its instances. struct Object { char val; - Object (char v) - : val (v) + Object () + : val ('?') { - Object::instances.push_back(this); log (this, "Object::Object"); + Object::instances.insert (this); } - Object () - : val ('?') + Object (const Object& that) + : val (that.val) { - Object::instances.push_back(this); log (this, "Object::Object"); + Object::instances.insert (this); } - Object& operator= (char v) + Object (char v) + : val (v) { - val = v; - return *this; + log (this, "Object::Object"); + Object::instances.insert (this); } ~Object () { - Object::instances.remove (this); log (this, "Object::~Object"); + objects::const_iterator i = instances.find (this); + // Make sure this object is alive. + assert (i != instances.end ()); + Object::instances.erase (i); + } + + Object& operator= (char v) + { + val = v; + return *this; } // Static part. - typedef std::list<const Object*> objects; + typedef std::set<const Object*> objects; static objects instances; static bool @@ -800,7 +814,8 @@ item: | 'p' { $$ = $][1; } | 's' { $$ = $][1; throw std::runtime_error ("reduction"); } | 'T' { ]AT_VARIANT_IF([], [$$ = YY_NULLPTR; delete $][1]; )[YYABORT; } -| error { ]AT_VARIANT_IF([], [$][$ = YY_NULLPTR; ])[yyerrok; } +]m4_if([$2], [with], +[[| error { $$ = ]AT_VARIANT_IF([], [new ])[Object ('R'); yyerrok; }]])[ ; %% @@ -903,16 +918,17 @@ AT_PARSER_CHECK([[./input aaaaE]], [[2]], [[]], AT_PARSER_CHECK([[./input aaaaT]], [[1]]) -# There is error-recovery, so exit success. -AT_PARSER_CHECK([[./input aaaaR]], [[0]]) +AT_PARSER_CHECK([[./input aaaaR]], [m4_if([$2], [with], [0], [1])]) AT_BISON_OPTION_POPDEFS AT_CLEANUP ]) -AT_TEST -AT_TEST([%define api.value.type variant]) +AT_TEST([], [with]) +AT_TEST([], [without]) +AT_TEST([%define api.value.type variant], [with]) +AT_TEST([%define api.value.type variant], [without]) m4_popdef([AT_TEST]) -- 1.8.4.2
