On 11/5/20 11:03 AM, Marek Polacek wrote:
This PR asks that we add a warning option for an existing (very old) warning, so that it can be disabled selectively. clang++ uses -Wexceptions for this, so I added this new option rather than using e.g. -Wnoexcept.
OK.
gcc/c-family/ChangeLog: PR c++/97675 * c.opt (Wexceptions): New option. gcc/cp/ChangeLog: PR c++/97675 * except.c (check_handlers_1): Use OPT_Wexceptions for the warning. Use inform for the second part of the warning. gcc/ChangeLog: PR c++/97675 * doc/invoke.texi: Document -Wexceptions. gcc/testsuite/ChangeLog: PR c++/97675 * g++.old-deja/g++.eh/catch10.C: Adjust dg-warning. * g++.dg/warn/Wexceptions1.C: New test. * g++.dg/warn/Wexceptions2.C: New test. --- gcc/c-family/c.opt | 4 ++++ gcc/cp/except.c | 9 ++++----- gcc/doc/invoke.texi | 8 +++++++- gcc/testsuite/g++.dg/warn/Wexceptions1.C | 9 +++++++++ gcc/testsuite/g++.dg/warn/Wexceptions2.C | 10 ++++++++++ gcc/testsuite/g++.old-deja/g++.eh/catch10.C | 4 ++-- 6 files changed, 36 insertions(+), 8 deletions(-) create mode 100644 gcc/testsuite/g++.dg/warn/Wexceptions1.C create mode 100644 gcc/testsuite/g++.dg/warn/Wexceptions2.C diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt index 426636be839..9493acb82ff 100644 --- a/gcc/c-family/c.opt +++ b/gcc/c-family/c.opt @@ -579,6 +579,10 @@ Werror-implicit-function-declaration C ObjC RejectNegative Warning Alias(Werror=, implicit-function-declaration) This switch is deprecated; use -Werror=implicit-function-declaration instead.+Wexceptions+C++ ObjC++ Var(warn_exceptions) Init(1) +Warn when an exception handler is shadowed by another handler. + Wextra C ObjC C++ ObjC++ Warning ; in common.opt diff --git a/gcc/cp/except.c b/gcc/cp/except.c index cb1a4105dae..985206f6a64 100644 --- a/gcc/cp/except.c +++ b/gcc/cp/except.c @@ -975,11 +975,10 @@ check_handlers_1 (tree master, tree_stmt_iterator i) tree handler = tsi_stmt (i); if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler))) { - warning_at (EXPR_LOCATION (handler), 0, - "exception of type %qT will be caught", - TREE_TYPE (handler)); - warning_at (EXPR_LOCATION (master), 0, - " by earlier handler for %qT", type); + if (warning_at (EXPR_LOCATION (handler), OPT_Wexceptions, + "exception of type %qT will be caught by earlier " + "handler", TREE_TYPE (handler))) + inform (EXPR_LOCATION (master), "for type %qT", type); break; } } diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 5320e6c1e1e..4c6435d5e14 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -240,7 +240,7 @@ in the following sections. -Wctor-dtor-privacy -Wno-delete-incomplete @gol -Wdelete-non-virtual-dtor -Wdeprecated-copy -Wdeprecated-copy-dtor @gol -Wno-deprecated-enum-enum-conversion -Wno-deprecated-enum-float-conversion @gol --Weffc++ -Wextra-semi -Wno-inaccessible-base @gol +-Weffc++ -Wno-exceptions -Wextra-semi -Wno-inaccessible-base @gol -Wno-inherited-variadic-ctor -Wno-init-list-lifetime @gol -Wno-invalid-offsetof -Wno-literal-suffix -Wmismatched-tags @gol -Wmultiple-inheritance -Wnamespaces -Wnarrowing @gol @@ -3738,6 +3738,12 @@ When selecting this option, be aware that the standard library headers do not obey all of these guidelines; use @samp{grep -v} to filter out those warnings.+@item -Wno-exceptions @r{(C++ and Objective-C++ only)}+@opindex Wexceptions +@opindex Wno-exceptions +Disable the warning about the case when an exception handler is shadowed by +another handler, which can point out a wrong ordering of exception handlers. + @item -Wstrict-null-sentinel @r{(C++ and Objective-C++ only)} @opindex Wstrict-null-sentinel @opindex Wno-strict-null-sentinel diff --git a/gcc/testsuite/g++.dg/warn/Wexceptions1.C b/gcc/testsuite/g++.dg/warn/Wexceptions1.C new file mode 100644 index 00000000000..af140fd0dc2 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wexceptions1.C @@ -0,0 +1,9 @@ +// PR c++/97675 + +struct Base { }; +struct Child : Base { }; +int main() { + try { throw Child(); } + catch (Base const&) { } + catch (Child const&) { } // { dg-warning "exception of type .Child. will be caught by earlier handler" } +} diff --git a/gcc/testsuite/g++.dg/warn/Wexceptions2.C b/gcc/testsuite/g++.dg/warn/Wexceptions2.C new file mode 100644 index 00000000000..07c5155ac06 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wexceptions2.C @@ -0,0 +1,10 @@ +// PR c++/97675 +// { dg-additional-options -Wno-exceptions } + +struct Base { }; +struct Child : Base { }; +int main() { + try { throw Child(); } + catch (Base const&) { } + catch (Child const&) { } // { dg-bogus "exception of type .Child. will be caught by earlier handler" } +} diff --git a/gcc/testsuite/g++.old-deja/g++.eh/catch10.C b/gcc/testsuite/g++.old-deja/g++.eh/catch10.C index 2300a946187..7cc609645a2 100644 --- a/gcc/testsuite/g++.old-deja/g++.eh/catch10.C +++ b/gcc/testsuite/g++.old-deja/g++.eh/catch10.C @@ -13,8 +13,8 @@ void g() catch (A*) { }try { f(); }- catch (A*) { } // { dg-warning "" } A* before B* - catch (B*) { } // { dg-warning "" } A* before B* + catch (A*) { } // { dg-message "for type" } A* before B* + catch (B*) { } // { dg-warning "will be caught" } A* before B*try { f(); }catch (A*) { } base-commit: fab72592d86d11b89a01f0f3c2c9c329d43466c1
