r338467 - Avoid exposing name for range-based for '__range' variables in lifetime warnings.

[David Blaikie via cfe-commits]

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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