r338467 - Avoid exposing name for range-based for '__range' variables in lifetime warnings.
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Tue Aug 7 14:35:24 PDT 2018
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 at 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 at 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>
>>
>>
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