On Mon, 21 Mar 2022, Jason Merrill via Gcc-patches wrote: > Our C++20 designated initializer handling was broken with members of class > type; we would find the relevant member and then try to find a member of > the member with the same name. Or we would sometimes ignore the designator > entirely. The former problem is fixed by the change to reshape_init_class, > the latter by the change to reshape_init_r. > > Tested x86_64-pc-linux-gnu, applying to trunk. > > PR c++/103337 > PR c++/102740 > PR c++/103299 > PR c++/102538 > > gcc/cp/ChangeLog: > > * decl.cc (reshape_init_class): Avoid looking for designator > after we found it. > (reshape_init_r): Keep looking for designator. > > gcc/testsuite/ChangeLog: > > * g++.dg/ext/flexary3.C: Remove one error. > * g++.dg/parse/pr43765.C: Likewise. > * g++.dg/cpp2a/desig22.C: New test. > * g++.dg/cpp2a/desig23.C: New test. > * g++.dg/cpp2a/desig24.C: New test. > * g++.dg/cpp2a/desig25.C: New test. > --- > gcc/cp/decl.cc | 47 +++++++++++++++++++++++++--- > gcc/testsuite/g++.dg/cpp2a/desig22.C | 11 +++++++ > gcc/testsuite/g++.dg/cpp2a/desig23.C | 20 ++++++++++++ > gcc/testsuite/g++.dg/cpp2a/desig24.C | 11 +++++++ > gcc/testsuite/g++.dg/cpp2a/desig25.C | 13 ++++++++ > gcc/testsuite/g++.dg/ext/flexary3.C | 2 +- > gcc/testsuite/g++.dg/parse/pr43765.C | 6 ++-- > 7 files changed, 101 insertions(+), 9 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/desig22.C > create mode 100644 gcc/testsuite/g++.dg/cpp2a/desig23.C > create mode 100644 gcc/testsuite/g++.dg/cpp2a/desig24.C > create mode 100644 gcc/testsuite/g++.dg/cpp2a/desig25.C > > diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc > index 375385e0013..34d9dad9fb0 100644 > --- a/gcc/cp/decl.cc > +++ b/gcc/cp/decl.cc > @@ -6598,8 +6598,9 @@ reshape_init_class (tree type, reshape_iter *d, bool > first_initializer_p, > { > tree field_init; > constructor_elt *old_cur = d->cur; > + bool direct_desig = false; > > - /* Handle designated initializers, as an extension. */ > + /* Handle C++20 designated initializers. */ > if (d->cur->index) > { > if (d->cur->index == error_mark_node) > @@ -6617,7 +6618,10 @@ reshape_init_class (tree type, reshape_iter *d, bool > first_initializer_p, > } > } > else if (TREE_CODE (d->cur->index) == IDENTIFIER_NODE) > - field = get_class_binding (type, d->cur->index); > + { > + field = get_class_binding (type, d->cur->index); > + direct_desig = true; > + } > else > { > if (complain & tf_error) > @@ -6669,6 +6673,7 @@ reshape_init_class (tree type, reshape_iter *d, bool > first_initializer_p, > break; > gcc_assert (aafield); > field = aafield; > + direct_desig = false; > } > } > > @@ -6683,9 +6688,32 @@ reshape_init_class (tree type, reshape_iter *d, bool > first_initializer_p, > assumed to correspond to no elements of the initializer list. */ > goto continue_; > > - field_init = reshape_init_r (TREE_TYPE (field), d, > - /*first_initializer_p=*/NULL_TREE, > - complain); > + if (direct_desig) > + { > + /* The designated field F is initialized from this one element: > + Temporarily clear the designator so a recursive reshape_init_class > + doesn't try to find it again in F, and adjust d->end so we don't > + try to use the next initializer to initialize another member of F. > + > + Note that we don't want these changes if we found the designator > + inside an anon aggr above; we leave them alone to implement: > + > + "If the element is an anonymous union member and the initializer > + list is a brace-enclosed designated- initializer-list, the element > + is initialized by the designated-initializer-list { D }, where D > + is the designated- initializer-clause naming a member of the > + anonymous union member." */ > + auto end_ = make_temp_override (d->end, d->cur + 1); > + auto idx_ = make_temp_override (d->cur->index, NULL_TREE);
IIUC this override of d->cur->index mutates the underlying CONSTRUCTOR, which is probably fine, but I wonder if it'd be worthwhile to avoid the mutation by using a temporary reshape_iter for the recursive call, something like: constructor_elt elt = { /*index=*/NULL_TREE, d->cur->value }; reshape_iter iter = { &elt, &elt + 1 }; field_init = reshape_init_r (TREE_TYPE (field), &iter, /*first_initializer_p=*/NULL_TREE, complain); d->cur++; > + field_init = reshape_init_r (TREE_TYPE (field), d, > + /*first_initializer_p=*/NULL_TREE, > + complain); > + } > + else > + field_init = reshape_init_r (TREE_TYPE (field), d, > + /*first_initializer_p=*/NULL_TREE, > + complain); > + > if (field_init == error_mark_node) > return error_mark_node; > > @@ -6941,6 +6969,15 @@ reshape_init_r (tree type, reshape_iter *d, tree > first_initializer_p, > to handle initialization of arrays and similar. */ > else if (COMPOUND_LITERAL_P (stripped_init)) > gcc_assert (!BRACE_ENCLOSED_INITIALIZER_P (stripped_init)); > + /* If we have an unresolved designator, we need to find the member it > + designates within TYPE, so proceed to the routines below. For > + FIELD_DECL or INTEGER_CST designators, we're already initializing > + the designated element. */ > + else if (d->cur->index > + && TREE_CODE (d->cur->index) == IDENTIFIER_NODE) > + /* Brace elision with designators is only permitted for anonymous > + aggregates. */ > + gcc_checking_assert (ANON_AGGR_TYPE_P (type)); > /* A CONSTRUCTOR of the target's type is a previously > digested initializer. */ > else if (same_type_ignoring_top_level_qualifiers_p (type, init_type)) > diff --git a/gcc/testsuite/g++.dg/cpp2a/desig22.C > b/gcc/testsuite/g++.dg/cpp2a/desig22.C > new file mode 100644 > index 00000000000..ba083f8e3d5 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/desig22.C > @@ -0,0 +1,11 @@ > +// PR c++/103337 > +// { dg-do compile { target c++20 } } > + > +struct op_t { > + struct put_t { > + int x; > + } put; > +}; > + > +op_t x{0}; // OK > +op_t y{.put=0}; // bogus error: 'op_t::put_t' has no non-static data member > named 'put' > diff --git a/gcc/testsuite/g++.dg/cpp2a/desig23.C > b/gcc/testsuite/g++.dg/cpp2a/desig23.C > new file mode 100644 > index 00000000000..4354e644f6a > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/desig23.C > @@ -0,0 +1,20 @@ > +// PR c++/102740 > +// { dg-do compile { target c++20 } } > +// { dg-additional-options -Wmissing-braces } > + > +typedef struct { > + union { > + struct { > + const void* content; > + } put; > + }; > +} op_t; > + > +op_t f(const char* alias) { > + return op_t{ > + .put = > + { > + .content = alias, > + }, > + }; // { dg-warning "missing braces" } > +} > diff --git a/gcc/testsuite/g++.dg/cpp2a/desig24.C > b/gcc/testsuite/g++.dg/cpp2a/desig24.C > new file mode 100644 > index 00000000000..219cc9c3b8e > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/desig24.C > @@ -0,0 +1,11 @@ > +// PR c++/103299 > +// { dg-do compile { target c++20 } } > + > +struct foo { > + union { > + int fp1{}; > + char fp2; > + }; > +}; > + > +static_assert(foo{.fp2={}}.fp2 == 0); > diff --git a/gcc/testsuite/g++.dg/cpp2a/desig25.C > b/gcc/testsuite/g++.dg/cpp2a/desig25.C > new file mode 100644 > index 00000000000..9da958c29e9 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/desig25.C > @@ -0,0 +1,13 @@ > +// PR c++/102538 > +// { dg-do run { target c++20 } } > + > +struct X { union { char r8[8]; int r32[2]; }; }; > +struct Y { X v[1]; }; > +Y x = { { { .r32 = { 5, 6 } } } }; > + > +int > +main () > +{ > + if (x.v[0].r32[0] != 5 || x.v[0].r32[1] != 6) > + __builtin_abort (); > +} > diff --git a/gcc/testsuite/g++.dg/ext/flexary3.C > b/gcc/testsuite/g++.dg/ext/flexary3.C > index 34b17254f8c..8344b42dd16 100644 > --- a/gcc/testsuite/g++.dg/ext/flexary3.C > +++ b/gcc/testsuite/g++.dg/ext/flexary3.C > @@ -16,7 +16,7 @@ struct s { > > int main() > { > - struct s s = { .c = 0 }; // { dg-error "initializer" } > + struct s s = { .c = 0 }; > // { dg-error "non-static initialization of a flexible array member" "" > { target *-*-* } .-1 } > return 0; > } > diff --git a/gcc/testsuite/g++.dg/parse/pr43765.C > b/gcc/testsuite/g++.dg/parse/pr43765.C > index 5e602204007..aa099a4d20b 100644 > --- a/gcc/testsuite/g++.dg/parse/pr43765.C > +++ b/gcc/testsuite/g++.dg/parse/pr43765.C > @@ -12,6 +12,6 @@ SomeType vals[] = > { > { 0, values : temp, }, // { dg-error "either all initializer > clauses should be designated or none of them should be" "" { target c++2a } } > 0 > - }; // { dg-error "GNU-style designated initializer for an array|cannot > convert" } > -// (note the error above is on the wrong line) > - // { dg-error "initialization of flexible array member in a nested > context" "" { target *-*-* } .-2 } > + }; > +// (note the error below is on the wrong line) > +// { dg-error "initialization of flexible array member in a nested context" > "" { target *-*-* } .-2 } > > base-commit: 70b8f43695b0e6fabc760d247ac83f354092b21d > prerequisite-patch-id: d89344aafac30ce0b8645945beb2d94b7ddb3515 > -- > 2.27.0 > >