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author | Marek Polacek <polacek@redhat.com> | 2021-11-03 11:04:22 -0400 |
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committer | Marek Polacek <polacek@redhat.com> | 2021-11-18 18:00:08 -0500 |
commit | 93810fd673654db9ff16170624a6d36449eab241 (patch) | |
tree | f31a7d9ee315aff919b2dd0a393c981dae0e4b54 /gcc/cp/typeck2.c | |
parent | 6f4ac4f81f89caac7e74127ed2e6db6bbb3d7426 (diff) | |
download | gcc-93810fd673654db9ff16170624a6d36449eab241.zip gcc-93810fd673654db9ff16170624a6d36449eab241.tar.gz gcc-93810fd673654db9ff16170624a6d36449eab241.tar.bz2 |
c++: Implement C++23 P0849R8 - auto(x) [PR103049]
This patch implements P0849R8 which allows auto in a functional cast,
the result of which is a prvalue.
[expr.type.conv]/1 says that the type is determined by placeholder type
deduction. We only accept 'auto', not 'decltype(auto)' -- that the
type shall be auto comes from [dcl.type.auto.deduct]. Therefore the
rules are like for [temp.deduct.call], deducing template arguments from
a function call, so the result type will never be a reference, and we
decay arrays/functions.
PR c++/103049
gcc/cp/ChangeLog:
* semantics.c (finish_compound_literal): Accept C++23 auto{x}.
* typeck2.c (build_functional_cast_1): Accept C++23 auto(x).
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/auto25.C: Adjust dg-error.
* g++.dg/cpp0x/auto9.C: Likewise.
* g++.dg/cpp2a/concepts-pr84979-2.C: Likewise.
* g++.dg/cpp2a/concepts-pr84979-3.C: Likewise.
* g++.dg/cpp23/auto-fncast1.C: New test.
* g++.dg/cpp23/auto-fncast2.C: New test.
* g++.dg/cpp23/auto-fncast3.C: New test.
* g++.dg/cpp23/auto-fncast4.C: New test.
* g++.dg/cpp23/auto-fncast5.C: New test.
* g++.dg/cpp23/auto-fncast6.C: New test.
Diffstat (limited to 'gcc/cp/typeck2.c')
-rw-r--r-- | gcc/cp/typeck2.c | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c index e98fbf7..3fb651a 100644 --- a/gcc/cp/typeck2.c +++ b/gcc/cp/typeck2.c @@ -2201,19 +2201,29 @@ build_functional_cast_1 (location_t loc, tree exp, tree parms, if (tree anode = type_uses_auto (type)) { - if (!CLASS_PLACEHOLDER_TEMPLATE (anode)) + tree init; + if (CLASS_PLACEHOLDER_TEMPLATE (anode)) + init = parms; + /* C++23 auto(x). */ + else if (!AUTO_IS_DECLTYPE (anode) + && list_length (parms) == 1) { - if (complain & tf_error) - error_at (loc, "invalid use of %qT", anode); - return error_mark_node; + init = TREE_VALUE (parms); + if (cxx_dialect < cxx23) + pedwarn (loc, OPT_Wc__23_extensions, + "%<auto(x)%> only available with " + "%<-std=c++2b%> or %<-std=gnu++2b%>"); } else { - type = do_auto_deduction (type, parms, anode, complain, - adc_variable_type); - if (type == error_mark_node) - return error_mark_node; + if (complain & tf_error) + error_at (loc, "invalid use of %qT", anode); + return error_mark_node; } + type = do_auto_deduction (type, init, anode, complain, + adc_variable_type); + if (type == error_mark_node) + return error_mark_node; } if (processing_template_decl) |