There's definitely scope for improving this diagnostic text further. Right now I don't think there's an easy way to figure out that the variable is the range variable in a range-based for loop, but I think that case is common enough that that's the level of special-case we should be looking at here. If we track that state, something like "error: range refers to a temporary object that will be destroyed before the first iteration of the loop" would seem much preferable.
On Tue, 7 Aug 2018 at 09:28, David Blaikie via cfe-commits < cfe-commits@lists.llvm.org> wrote: > Reckon there's a chance of improved diagnostic text in cases like this? > Will users understand what the problem is/how to fix it when they read > "temporary > implicitly bound to local reference will be destroyed at the end of the > full-expression" - feels very standard-ese-y to me? & I appreciate teh > desire/need for precision, I wonder if there's better ways to communicate > it to the user... :/ > > On Tue, Jul 31, 2018 at 6:03 PM Richard Smith via cfe-commits < > cfe-commits@lists.llvm.org> wrote: > >> Author: rsmith >> Date: Tue Jul 31 18:03:33 2018 >> New Revision: 338467 >> >> URL: http://llvm.org/viewvc/llvm-project?rev=338467&view=rev >> Log: >> Avoid exposing name for range-based for '__range' variables in lifetime >> warnings. >> >> Modified: >> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td >> cfe/trunk/lib/Sema/SemaInit.cpp >> cfe/trunk/test/SemaCXX/attr-lifetimebound.cpp >> >> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=338467&r1=338466&r2=338467&view=diff >> >> ============================================================================== >> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original) >> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Jul 31 >> 18:03:33 2018 >> @@ -7875,7 +7875,8 @@ def warn_ret_addr_label : Warning< >> def err_ret_local_block : Error< >> "returning block that lives on the local stack">; >> def note_local_var_initializer : Note< >> - "%select{via initialization of|binding reference}0 variable %1 here">; >> + "%select{via initialization of|binding reference}0 variable " >> + "%select{%2 |}1here">; >> def note_init_with_default_member_initalizer : Note< >> "initializing field %0 with default member initializer">; >> >> @@ -7907,13 +7908,14 @@ def note_lifetime_extending_member_decla >> "member with %select{reference|'std::initializer_list'}0 subobject}1 " >> "declared here">; >> def warn_dangling_variable : Warning< >> - "%select{temporary %select{whose address is used as value of|bound >> to}3 " >> - "%select{%select{|reference }3member of local variable|" >> - "local %select{variable|reference}3}1|" >> + "%select{temporary %select{whose address is used as value of|" >> + "%select{|implicitly }2bound to}4 " >> + "%select{%select{|reference }4member of local variable|" >> + "local %select{variable|reference}4}1|" >> "array backing " >> "%select{initializer list subobject of local variable|" >> "local initializer list}1}0 " >> - "%2 will be destroyed at the end of the full-expression">, >> + "%select{%3 |}2will be destroyed at the end of the full-expression">, >> InGroup<Dangling>; >> def warn_new_dangling_reference : Warning< >> "temporary bound to reference member of allocated object " >> >> Modified: cfe/trunk/lib/Sema/SemaInit.cpp >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaInit.cpp?rev=338467&r1=338466&r2=338467&view=diff >> >> ============================================================================== >> --- cfe/trunk/lib/Sema/SemaInit.cpp (original) >> +++ cfe/trunk/lib/Sema/SemaInit.cpp Tue Jul 31 18:03:33 2018 >> @@ -6847,8 +6847,9 @@ void Sema::checkInitializerLifetime(cons >> return false; >> >> Diag(DiagLoc, diag::warn_dangling_variable) >> - << RK << !Entity.getParent() << ExtendingEntity->getDecl() >> - << Init->isGLValue() << DiagRange; >> + << RK << !Entity.getParent() >> + << ExtendingEntity->getDecl()->isImplicit() >> + << ExtendingEntity->getDecl() << Init->isGLValue() << >> DiagRange; >> } >> break; >> } >> @@ -6969,7 +6970,8 @@ void Sema::checkInitializerLifetime(cons >> case IndirectLocalPathEntry::VarInit: >> const VarDecl *VD = cast<VarDecl>(Elem.D); >> Diag(VD->getLocation(), diag::note_local_var_initializer) >> - << VD->getType()->isReferenceType() << VD->getDeclName() >> + << VD->getType()->isReferenceType() >> + << VD->isImplicit() << VD->getDeclName() >> << nextPathEntryRange(Path, I + 1, L); >> break; >> } >> >> Modified: cfe/trunk/test/SemaCXX/attr-lifetimebound.cpp >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/attr-lifetimebound.cpp?rev=338467&r1=338466&r2=338467&view=diff >> >> ============================================================================== >> --- cfe/trunk/test/SemaCXX/attr-lifetimebound.cpp (original) >> +++ cfe/trunk/test/SemaCXX/attr-lifetimebound.cpp Tue Jul 31 18:03:33 2018 >> @@ -101,7 +101,7 @@ namespace p0936r0_examples { >> std::vector make_vector(); >> void use_reversed_range() { >> // FIXME: Don't expose the name of the internal range variable. >> - for (auto x : reversed(make_vector())) {} // expected-warning >> {{temporary bound to local reference '__range1'}} >> + for (auto x : reversed(make_vector())) {} // expected-warning >> {{temporary implicitly bound to local reference will be destroyed at the >> end of the full-expression}} >> } >> >> template <typename K, typename V> >> >> >> _______________________________________________ >> cfe-commits mailing list >> cfe-commits@lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >> > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >
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