On Mon, Sep 18, 2023 at 9:36 AM Jason Merrill <ja...@redhat.com> wrote:
>
> On 9/18/23 08:58, Patrick Palka wrote:
> > On Sun, 17 Sep 2023, Jason Merrill wrote:
> >
> >> On 9/17/23 15:13, Patrick Palka wrote:
> >>> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> >>> trunk?
> >>>
> >>> -- >8 --
> >>>
> >>> r14-2655-g92d1425ca78040 made instantiate_template avoid redundantly
> >>> performing a specialization lookup when instantiating a function or
> >>> alias template. This patch applies the same optimization to
> >>> tsubst_template_decl when (partially) instantiating a function template,
> >>> which allows us to remove a check from register_specialization since
> >>> tsubst_function_decl no longer calls register_specialization for
> >>> a function template partial instantiation.
> >>>
> >>> gcc/cp/ChangeLog:
> >>>
> >>> * pt.cc (register_specialization): Remove now-unnecessary
> >>> early exit for FUNCTION_DECL partial instantiation.
> >>> (tsubst_template_decl): Pass use_spec_table=false to
> >>> tsubst_function_decl. Set DECL_TI_ARGS of a non-lambda
> >>> FUNCTION_DECL specialization to the full set of arguments.
> >>> Simplify register_specialization call accordingly.
> >>>
> >>> gcc/testsuite/ChangeLog:
> >>>
> >>> * g++.dg/template/nontype12.C: Expect two instead of three
> >>> duplicate diagnostics for A<double>::bar() specialization.
> >>> ---
> >>> gcc/cp/pt.cc | 29 +++++++----------------
> >>> gcc/testsuite/g++.dg/template/nontype12.C | 1 -
> >>> 2 files changed, 9 insertions(+), 21 deletions(-)
> >>>
> >>> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> >>> index c311a6b88f5..a0296a1ea16 100644
> >>> --- a/gcc/cp/pt.cc
> >>> +++ b/gcc/cp/pt.cc
> >>> @@ -1507,21 +1507,6 @@ register_specialization (tree spec, tree tmpl, tree
> >>> args, bool is_friend,
> >>> || (TREE_CODE (tmpl) == FIELD_DECL
> >>> && TREE_CODE (spec) == NONTYPE_ARGUMENT_PACK));
> >>> - if (TREE_CODE (spec) == FUNCTION_DECL
> >>> - && uses_template_parms (DECL_TI_ARGS (spec)))
> >>> - /* This is the FUNCTION_DECL for a partial instantiation. Don't
> >>> - register it; we want the corresponding TEMPLATE_DECL instead.
> >>> - We use `uses_template_parms (DECL_TI_ARGS (spec))' rather than
> >>> - the more obvious `uses_template_parms (spec)' to avoid problems
> >>> - with default function arguments. In particular, given
> >>> - something like this:
> >>> -
> >>> - template <class T> void f(T t1, T t = T())
> >>> -
> >>> - the default argument expression is not substituted for in an
> >>> - instantiation unless and until it is actually needed. */
> >>> - return spec;
> >>> -
> >>> spec_entry elt;
> >>> elt.tmpl = tmpl;
> >>> elt.args = args;
> >>> @@ -14663,7 +14648,7 @@ tsubst_template_decl (tree t, tree args,
> >>> tsubst_flags_t complain,
> >>> tree in_decl = t;
> >>> tree spec;
> >>> tree tmpl_args;
> >>> - tree full_args;
> >>> + tree full_args = NULL_TREE;
> >>> tree r;
> >>> hashval_t hash = 0;
> >>> @@ -14754,7 +14739,8 @@ tsubst_template_decl (tree t, tree args,
> >>> tsubst_flags_t complain,
> >>> tree inner = decl;
> >>> ++processing_template_decl;
> >>> if (TREE_CODE (inner) == FUNCTION_DECL)
> >>> - inner = tsubst_function_decl (inner, args, complain, lambda_fntype);
> >>> + inner = tsubst_function_decl (inner, args, complain, lambda_fntype,
> >>> + /*use_spec_table=*/false);
> >>> else
> >>> {
> >>> if (TREE_CODE (inner) == TYPE_DECL && !TYPE_DECL_ALIAS_P (inner))
> >>> @@ -14792,6 +14778,11 @@ tsubst_template_decl (tree t, tree args,
> >>> tsubst_flags_t complain,
> >>> }
> >>> else
> >>> {
> >>> + if (TREE_CODE (inner) == FUNCTION_DECL)
> >>> + /* Set DECL_TI_ARGS to the full set of template arguments, which
> >>> + tsubst_function_decl didn't do due to use_spec_table=false. */
> >>> + DECL_TI_ARGS (inner) = full_args;
> >>> +
> >>> DECL_TI_TEMPLATE (inner) = r;
> >>> DECL_TI_ARGS (r) = DECL_TI_ARGS (inner);
> >>> }
> >>> @@ -14822,9 +14813,7 @@ tsubst_template_decl (tree t, tree args,
> >>> tsubst_flags_t complain,
> >>> if (TREE_CODE (decl) == FUNCTION_DECL && !lambda_fntype)
> >>> /* Record this non-type partial instantiation. */
> >>> - register_specialization (r, t,
> >>> - DECL_TI_ARGS (DECL_TEMPLATE_RESULT (r)),
> >>> - false, hash);
> >>> + register_specialization (r, t, full_args, false, hash);
> >>> return r;
> >>> }
> >>> diff --git a/gcc/testsuite/g++.dg/template/nontype12.C
> >>> b/gcc/testsuite/g++.dg/template/nontype12.C
> >>> index 9a9c3ac1e66..e36a9f16f94 100644
> >>> --- a/gcc/testsuite/g++.dg/template/nontype12.C
> >>> +++ b/gcc/testsuite/g++.dg/template/nontype12.C
> >>> @@ -5,7 +5,6 @@ template<typename T> struct A
> >>> {
> >>> template<T> int foo(); // { dg-error "double"
> >>> ""
> >>> { target c++17_down } }
> >>> template<template<T> class> int bar(); // { dg-bogus
> >>> {double[^\n]*\n[^\n]*C:7:[^\n]*double} "" { xfail c++17_down } }
> >>> - // { dg-error "double" "" { target c++17_down } .-1 }
> >>
> >> Hmm, I thought this line was to check that we get one error even if we
> >> don't
> >> want two?
> >
> > The xfailed dg-bogus directive seems to "consume" the two errors, and
> > prevents the dg-error from matching either of them. Before this patch,
> > we issued three duplicate errors and so this arrangement worked out
> > since the xfailed dg-bogus consumes only two of the errors. I'm not
> > sure how to express that we're currently seeing two errors but only want
> > one using _both_ dg-error and dg-bogus..
>
> Would it work to have a dg-error to consume one error followed by a
> dg-bogus for another single error?
Unfortunately not, because it seems if we have a dg-error first then it consumes
all the matching errors on the line, and then a subsequent dg-bogus always
succeeds even if there were duplicate errors.
>
> If not, just add a comment. OK either way.
Thanks a lot, will do.
>
> Jason
>
