On Tue, 6 Aug 2024, Jason Merrill wrote:
> On 8/6/24 2:00 PM, Patrick Palka wrote:
> > On Tue, 6 Aug 2024, Jason Merrill wrote:
> >
> > > On 8/5/24 6:09 PM, Patrick Palka wrote:
> > > > On Mon, 5 Aug 2024, Jason Merrill wrote:
> > > >
> > > > > On 8/5/24 3:47 PM, Patrick Palka wrote:
> > > > > > On Mon, 5 Aug 2024, Jason Merrill wrote:
> > > > > >
> > > > > > > On 8/5/24 1:14 PM, Patrick Palka wrote:
> > > > > > > > On Mon, 5 Aug 2024, Jason Merrill wrote:
> > > > > > > >
> > > > > > > > > On 8/2/24 4:18 PM, Patrick Palka wrote:
> > > > > > > > > > On Fri, 2 Aug 2024, Patrick Palka wrote:
> > > > > > > > > >
> > > > > > > > > > > On Fri, 2 Aug 2024, Jason Merrill wrote:
> > > > > > > > > > >
> > > > > > > > > > > > On 8/1/24 2:52 PM, Patrick Palka wrote:
> > > > > > > > > > > > > In recent versions of GCC we've been diagnosing more
> > > > > > > > > > > > > and
> > > > > > > > > > > > > more
> > > > > > > > > > > > > kinds of
> > > > > > > > > > > > > errors inside a template ahead of time. This is a
> > > > > > > > > > > > > largely
> > > > > > > > > > > > > good
> > > > > > > > > > > > > thing
> > > > > > > > > > > > > because it catches bugs, typos, dead code etc sooner.
> > > > > > > > > > > > >
> > > > > > > > > > > > > But if the template never gets instantiated then such
> > > > > > > > > > > > > errors
> > > > > > > > > > > > > are
> > > > > > > > > > > > > harmless, and can be inconvenient to work around if
> > > > > > > > > > > > > say
> > > > > > > > > > > > > the
> > > > > > > > > > > > > code
> > > > > > > > > > > > > in
> > > > > > > > > > > > > question is third party and in maintenence mode. So
> > > > > > > > > > > > > it'd
> > > > > > > > > > > > > be
> > > > > > > > > > > > > useful to
> > > > > > > > > > > >
> > > > > > > > > > > > "maintenance"
> > > > > > > > > > >
> > > > > > > > > > > Fixed
> > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
> > > > > > > > > > > > > index d80bac822ba..0bb0a482e28 100644
> > > > > > > > > > > > > --- a/gcc/cp/error.cc
> > > > > > > > > > > > > +++ b/gcc/cp/error.cc
> > > > > > > > > > > > > @@ -165,6 +165,58 @@ class cxx_format_postprocessor :
> > > > > > > > > > > > > public
> > > > > > > > > > > > > format_postprocessor
> > > > > > > > > > > > > deferred_printed_type m_type_b;
> > > > > > > > > > > > > };
> > > > > > > > > > > > > +/* A map from TEMPLATE_DECL to the location of
> > > > > > > > > > > > > the
> > > > > > > > > > > > > first
> > > > > > > > > > > > > error (if
> > > > > > > > > > > > > any)
> > > > > > > > > > > > > + within the template that we permissivly downgraded
> > > > > > > > > > > > > to
> > > > > > > > > > > > > a
> > > > > > > > > > > > > warning.
> > > > > > > > > > > > > */
> > > > > > > > > > > >
> > > > > > > > > > > > "permissively"
> > > > > > > > > > >
> > > > > > > > > > > Fixed
> > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > +relaxed_template_errors_t *relaxed_template_errors;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +/* Callback function
> > > > > > > > > > > > > diagnostic_context::m_adjust_diagnostic_info.
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + In -fpermissive mode we downgrade errors within a
> > > > > > > > > > > > > template
> > > > > > > > > > > > > to
> > > > > > > > > > > > > + warnings, and only issue an error if we later need
> > > > > > > > > > > > > to
> > > > > > > > > > > > > instantiate
> > > > > > > > > > > > > + the template. */
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +static void
> > > > > > > > > > > > > +cp_adjust_diagnostic_info (diagnostic_context
> > > > > > > > > > > > > *context,
> > > > > > > > > > > > > + diagnostic_info
> > > > > > > > > > > > > *diagnostic)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + tree ti;
> > > > > > > > > > > > > + if (diagnostic->kind == DK_ERROR
> > > > > > > > > > > > > + && context->m_permissive
> > > > > > > > > > > > > + && !current_instantiation ()
> > > > > > > > > > > > > + && in_template_context
> > > > > > > > > > > > > + && (ti = get_template_info (current_scope ())))
> > > > > > > > > > > > > + {
> > > > > > > > > > > > > + if (!relaxed_template_errors)
> > > > > > > > > > > > > + relaxed_template_errors = new
> > > > > > > > > > > > > relaxed_template_errors_t;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + tree tmpl = TI_TEMPLATE (ti);
> > > > > > > > > > > > > + if (!relaxed_template_errors->get (tmpl))
> > > > > > > > > > > > > + relaxed_template_errors->put (tmpl,
> > > > > > > > > > > > > diagnostic->richloc->get_loc ());
> > > > > > > > > > > > > + diagnostic->kind = DK_WARNING;
> > > > > > > > > > > >
> > > > > > > > > > > > Rather than check m_permissive directly and downgrade to
> > > > > > > > > > > > DK_WARNING,
> > > > > > > > > > > > how
> > > > > > > > > > > > about
> > > > > > > > > > > > downgrading to DK_PERMERROR? That way people will get
> > > > > > > > > > > > the
> > > > > > > > > > > > [-fpermissive]
> > > > > > > > > > > > clue.
> > > > > > > > > > > >
> > > > > > > > > > > > ...though I suppose DK_PERMERROR doesn't work where you
> > > > > > > > > > > > call
> > > > > > > > > > > > this
> > > > > > > > > > > > hook
> > > > > > > > > > > > in
> > > > > > > > > > > > report_diagnostic, at which point we've already
> > > > > > > > > > > > reassigned
> > > > > > > > > > > > it
> > > > > > > > > > > > into
> > > > > > > > > > > > DK_WARNING
> > > > > > > > > > > > or DK_ERROR in diagnostic_impl.
> > > > > > > > > > > >
> > > > > > > > > > > > But we could still set diagnostic->option_index even for
> > > > > > > > > > > > DK_ERROR,
> > > > > > > > > > > > whether to
> > > > > > > > > > > > context->m_opt_permissive or to its own warning flag,
> > > > > > > > > > > > perhaps
> > > > > > > > > > > > -Wno-template-body?
> > > > > > > > > > >
> > > > > > > > > > > Fixed by adding an enabled-by-default -Wtemplate-body flag
> > > > > > > > > > > and
> > > > > > > > > > > setting
> > > > > > > > > > > option_index to it for each downgraded error. Thus
> > > > > > > > > > > -permissive
> > > > > > > > > > > -Wno-template-body would suppress the downgraded warnings
> > > > > > > > > > > entirely,
> > > > > > > > > > > and
> > > > > > > > > > > only issue a generic error upon instantiation of the
> > > > > > > > > > > erroneous
> > > > > > > > > > > template.
> > > > > > > > > >
> > > > > > > > > > ... or did you have in mind to set option_index even when
> > > > > > > > > > not
> > > > > > > > > > using
> > > > > > > > > > -fpermissive so that eligible non-downgraded errors get the
> > > > > > > > > > [-fpermissive] or [-Wtemplate-body] hint as well?
> > > > > > > > >
> > > > > > > > > Yes.
> > > > > > > > >
> > > > > > > > > > IMHO I'm not sure that'd be worth the extra noise since the
> > > > > > > > > > vast
> > > > > > > > > > majority of users appreciate and expect errors to get
> > > > > > > > > > diagnosed
> > > > > > > > > > inside
> > > > > > > > > > templates.
> > > > > > > > >
> > > > > > > > > But people trying to build legacy code should appreciate the
> > > > > > > > > pointer
> > > > > > > > > for
> > > > > > > > > how
> > > > > > > > > to make it compile, as with other permerrors.
> > > > > > > > >
> > > > > > > > > > And on second thought I'm not sure what extra value a new
> > > > > > > > > > warning
> > > > > > > > > > flag
> > > > > > > > > > adds either. I can't think of a good reason why one would
> > > > > > > > > > use
> > > > > > > > > > -fpermissive -Wno-template-body?
> > > > > > > > >
> > > > > > > > > One would use -Wno-template-body (or -Wno-error=template-body)
> > > > > > > > > without
> > > > > > > > > -fpermissive, like with the various permerror_opt cases.
> > > > > > > >
> > > > > > > > Since compiling legacy/unmaintained code is the only plausible
> > > > > > > > use
> > > > > > > > case,
> > > > > > > > why have a dedicated warning flag instead of just recommending
> > > > > > > > -fpermissive
> > > > > > > > when compiling legacy code? I don't quite understand the
> > > > > > > > motivation
> > > > > > > > for
> > > > > > > > adding a new permerror_opt flag for this class of errors.
> > > > > > >
> > > > > > > It seems to me an interesting class of errors, but I don't mind
> > > > > > > leaving it
> > > > > > > under just -fpermissive if you prefer.
> > > > > > >
> > > > > > > > -Wnarrowing is an existing permerror_opt flag, but I can imagine
> > > > > > > > it's
> > > > > > > > useful to pass -Wno-error=narrowing etc when incrementally
> > > > > > > > migrating
> > > > > > > > C / C++98 code to modern C++ where you don't want any
> > > > > > > > conformance
> > > > > > > > errors
> > > > > > > > allowed by -fpermissive to sneak in. So being able to narrowly
> > > > > > > > control
> > > > > > > > this class of errors seems useful, so a dedicated flag makes
> > > > > > > > sense.
> > > > > > > >
> > > > > > > > But there's no parallel for -Wtemplate-body here, since by
> > > > > > > > assumption
> > > > > > > > the code base is unmaintained / immutable. Otherwise the more
> > > > > > > > proper
> > > > > > > > fix would be to just fix and/or delete the uninstantiated
> > > > > > > > erroneous
> > > > > > > > template. If say you're #including a legacy header that has
> > > > > > > > such
> > > > > > > > errors, then doing #pragma GCC diagnostic "-fpermissive -w"
> > > > > > > > around
> > > > > > > > the #include should be totally fine too.
> > > > > >
> > > > > > I just realized #pragma GCC diagnostic warning "-fpermissive" etc
> > > > > > doesn't actually work since -fpermissive isn't a warning flag. So
> > > > > > having a dedicated flag for the class of errors has at least one
> > > > > > clear
> > > > > > benefit -- we can use #pragmas to selectively disable the errors
> > > > > > now.
> > > > > >
> > > > > > > >
> > > > > > > > I just don't see the use case for being able to narrowly control
> > > > > > > > this
> > > > > > > > class of errors that justifies the extra implementation
> > > > > > > > complexity
> > > > > > > > (specifically for properly detecting -Wno-error=template-body in
> > > > > > > > the
> > > > > > > > callback hook)?
> > > > > > >
> > > > > > > The hook shouldn't need to do anything special; report_diagnostic
> > > > > > > handles
> > > > > > > -Wno-error=whatever.
> > > > > >
> > > > > > The issue was that the callback has to know in advance whether
> > > > > > -Wno-error=template-body is active so that it can flag the template
> > > > > > as
> > > > > > having a relaxed error. Checking !warning_enabled_at wasn't enough
> > > > > > because it will return true even for -Wno-error=template-body. I
> > > > > > think we just need to check diagnostic_enabled directly, like so?
> > > > >
> > > > > Why not always flag it? It doesn't seem harmful to give the
> > > > > "instatiating
> > > > > erroneous template" error later even if we gave a hard error during
> > > > > parsing.
> > > >
> > > > Hmm, it just seems redundant to me I guess? The reason we need the
> > > > "instantiating erroneous template" error is to ensure that _some_ error
> > > > was issued rendering the TU ill-formed when an erroneous template gets
> > > > instantiated. If parse-time errors are hard errors then this is
> > > > guaranteed, but it's not if we're downgrading such errors.
> > >
> > > Yes, it's redundant, but avoiding it doesn't seem worth duplicating all
> > > the
> > > logic to determine whether it will be an error or not.
> > >
> > > Simpler might be to skip the "instantiating" error if seen_error()?
> >
> > Sure. This makes the expected diagnostics in the -Wno-template-body
> > testcase a bit lacking since there's three instantiated templates with
> > one logical error each, but only the first error is diagnosed. But I
> > don't particularly mind that.
> >
> > >
> > > > On that note it just occurred to me that we don't need to abort
> > > > instantiation after the "instantiating erroneous template" error --
> > > > for sake of error recovery we can proceed to instantiate as if we
> > > > issued a hard error at parse time.
> > >
> > > Agreed.
> > >
> > > Jason
> > >
> > >
> >
> > -- >8 --
> >
> > Subject: [PATCH] c++: permit errors inside uninstantiated templates
> > [PR116064]
> >
> > In recent versions of GCC we've been diagnosing more and more kinds of
> > errors inside a template ahead of time. This is a largely good thing
> > because it catches bugs, typos, dead code etc sooner.
> >
> > But if the template never gets instantiated then such errors are harmless
> > and can be inconvenient to work around if say the code in question is
> > third party and in maintenance mode. So it'd be handy to be able to
> > prevent these template errors from rendering the entire TU uncompilable.
> > (Note that such code is "ill-formed no diagnostic required" according
> > the standard.)
> >
> > To that end this patch turns any errors issued within a template into
> > premerrors associated with a new -Wtemplate-body flag so that they can
>
> perm
>
> > be downgraded via e.g. -fpermissive or -Wno-template=template-body. If
> > the template containing a downgraded error later needs to be instantiated,
> > we'll issue an error then. But if the template never gets instantiated
> > then the downgraded error won't affect validity of the rest of the TU.
> >
> > This is implemented via a diagnostic hook that gets called for each
> > diagnostic, and which adjusts an error diagnostic if we detect it's
> > occurring from a template context and additionally flags this template
> > context as erroneous.
> >
> > As an example, permissive-error1a.C gives:
> >
> > gcc/testsuite/g++.dg/template/permissive-error1a.C: In function 'void f()':
> > gcc/testsuite/g++.dg/template/permissive-error1a.C:7:5: warning: increment
> > of read-only variable 'n' [-Wtemplate-body]
> > 7 | ++n;
> > | ^
> > ...
> > gcc/testsuite/g++.dg/template/permissive-error1a.C: In instantiation of
> > 'void f() [with T = int]':
> > gcc/testsuite/g++.dg/template/permissive-error1a.C:26:9: required from
> > here
> > 26 | f<int>();
> > | ~~~~~~^~
> > gcc/testsuite/g++.dg/template/permissive-error1a.C:5:6: error: instantiating
> > erroneous template pattern
>
> Drop "pattern" here too.
Fixed
>
> > 5 | void f() {
> > | ^
> > gcc/testsuite/g++.dg/template/permissive-error1a.C:7:5: note: first error
> > appeared here
> > 7 | ++n; // {
> > | ^
> > ...
>
> What happens if we compile an interface/header unit with an erroneous
> uninstantiated template? I'd probably reject such a module rather than write
> out the erroneity. Possibly just if the template isn't discarded, not sure if
> that distinction is too much trouble to bother with.
I think it's good enough to uniformly reject the module given how small
the intersection -fpermissive and modules users is, I imagine.
>
> > PR c++/116064
> >
> > gcc/c-family/ChangeLog:
> >
> > * c.opt (Wtemplate-body): New warning.
> >
> > gcc/cp/ChangeLog:
> >
> > * cp-tree.h (erroneous_templates_t): Declare.
> > (erroneous_templates): Declare.
> > (cp_seen_error): Declare.
> > (basic_seen_error): Define as alias to existing seen_error.
>
> Or we could use (seen_error)() where we mean the basic one?
Sure, changed.
>
> > (seen_error): #define to cp_seen_error.
> > * error.cc (get_current_template): Define.
> > (relaxed_template_errors): Define.
> > (cp_adjust_diagnostic_info): Define.
> > (cp_seen_error): Define.
> > (cxx_initialize_diagnostics): Set
> > diagnostic_context::m_adjust_diagnostic_info.
> > * pt.cc (instantiate_class_template): Issue a hard error
> > when trying to instantiate a template pattern containing
> > a permissively downgraded error.
> > (instantiate_decl): Likewise.
> >
> > gcc/ChangeLog:
> >
> > * diagnostic.cc (diagnostic_context::initialize): Set
> > m_adjust_diagnostic_info.
> > (diagnostic_context::report_diagnostic): Call
> > m_adjust_diagnostic_info.
> > * diagnostic.h (diagnostic_context::diagnostic_enabled): Make
> > public.
>
> You shouldn't need this change now?
Oops, removed.
>
> > +static void
> > +cp_adjust_diagnostic_info (diagnostic_context *context,
> > + diagnostic_info *diagnostic)
> > +{
> > + if (diagnostic->kind == DK_ERROR)
> > + if (tree tmpl = get_current_template ())
> > + {
> > + diagnostic->option_index = OPT_Wtemplate_body;
> > +
> > + if (context->m_permissive)
> > + diagnostic->kind = DK_WARNING;
> > +
> > + if (!erroneous_templates)
> > + erroneous_templates = new erroneous_templates_t;
> > + if (!erroneous_templates->get (tmpl))
> > + {
> > + /* Remember that this template had a parse-time error so
> > + that we'll ensure a hard error has been issued upon
> > + its instantiation. */
> > + location_t error_loc = diagnostic->richloc->get_loc ();
> > + erroneous_templates->put (tmpl, error_loc);
>
> Instead of get+put you could use the get return value to store error_loc?
We need to use get_or_insert if we want to combine the two lookups.
I went ahead and used hash_map_safe_get_or_insert here to get rid
of the construction boilerplate as well.
>
> > +@opindex Wtemplate-body
> > +@opindex Wno-template-body
> > +@item -Wno-template-body @r{(C++ and Objective-C++ only)}
> > +Disable diagnosing errors when parsing a template, and instead issue an
> > +error only upon instantiation of the template. This flag can also be
> > +used to downgrade such errors into warnings with @option{Wno-error=} or
> > +@option{-fpermissive}.
>
> Please also refer to this flag in the -fpermissive documentation.
Done.
-- >8 --
Subject: [PATCH] c++: permit errors inside uninstantiated templates [PR116064]
In recent versions of GCC we've been diagnosing more and more kinds of
errors inside a template ahead of time. This is a largely good thing
because it catches bugs, typos, dead code etc sooner.
But if the template never gets instantiated then such errors are harmless
and can be inconvenient to work around if say the code in question is
third party and in maintenance mode. So it'd be handy to be able to
prevent these template errors from rendering the entire TU uncompilable.
(Note that such code is "ill-formed no diagnostic required" according
the standard.)
To that end this patch turns any errors issued within a template into
permerrors associated with a new -Wtemplate-body flag so that they can
be downgraded via e.g. -fpermissive or -Wno-template=template-body. If
the template containing a downgraded error later needs to be instantiated,
we'll issue an error then. But if the template never gets instantiated
then the downgraded error won't affect validity of the rest of the TU.
This is implemented via a diagnostic hook that gets called for each
diagnostic, and which adjusts an error diagnostic if we detect it's
occurring from a template context and additionally flags this template
context as erroneous.
As an example, permissive-error1a.C gives:
gcc/testsuite/g++.dg/template/permissive-error1a.C: In function 'void f()':
gcc/testsuite/g++.dg/template/permissive-error1a.C:7:5: warning: increment of
read-only variable 'n' [-Wtemplate-body]
7 | ++n;
| ^
...
gcc/testsuite/g++.dg/template/permissive-error1a.C: In instantiation of 'void
f() [with T = int]':
gcc/testsuite/g++.dg/template/permissive-error1a.C:26:9: required from here
26 | f<int>();
| ~~~~~~^~
gcc/testsuite/g++.dg/template/permissive-error1a.C:5:6: error: instantiating
erroneous template
5 | void f() {
| ^
gcc/testsuite/g++.dg/template/permissive-error1a.C:7:5: note: first error
appeared here
7 | ++n; // {
| ^
...
PR c++/116064
gcc/c-family/ChangeLog:
* c.opt (Wtemplate-body): New warning.
gcc/cp/ChangeLog:
* cp-tree.h (erroneous_templates_t): Declare.
(erroneous_templates): Declare.
(cp_seen_error): Declare.
(seen_error): #define to cp_seen_error.
* error.cc (get_current_template): Define.
(relaxed_template_errors): Define.
(cp_adjust_diagnostic_info): Define.
(cp_seen_error): Define.
(cxx_initialize_diagnostics): Set
diagnostic_context::m_adjust_diagnostic_info.
* module.cc (finish_module_processing): Don't write the
module if it contains an erroneous template.
* pt.cc (instantiate_class_template): Issue a hard error
when trying to instantiate a template containing a
permissively downgraded error.
(instantiate_decl): Likewise.
gcc/ChangeLog:
* diagnostic.cc (diagnostic_context::initialize): Set
m_adjust_diagnostic_info.
(diagnostic_context::report_diagnostic): Call
m_adjust_diagnostic_info.
* diagnostic.h (diagnostic_context::m_adjust_diagnostic_info):
New data member.
* doc/invoke.texi (-Wno-template-body): Document.
(-fpermissive): Mention -Wtemplate-body.
gcc/testsuite/ChangeLog:
* g++.dg/ext/typedef-init.C: Downgrade error inside template
to warning due to -fpermissive.
* g++.dg/pr84492.C: Likewise.
* g++.old-deja/g++.pt/crash51.C: Remove unneeded dg-options.
* g++.dg/template/permissive-error1.C: New test.
* g++.dg/template/permissive-error1a.C: New test.
* g++.dg/template/permissive-error1b.C: New test.
* g++.dg/template/permissive-error1c.C: New test.
---
gcc/c-family/c.opt | 4 ++
gcc/cp/cp-tree.h | 7 ++
gcc/cp/error.cc | 67 +++++++++++++++++++
gcc/cp/module.cc | 5 +-
gcc/cp/pt.cc | 24 +++++++
gcc/diagnostic.cc | 4 ++
gcc/diagnostic.h | 4 ++
gcc/doc/invoke.texi | 12 +++-
gcc/testsuite/g++.dg/ext/typedef-init.C | 2 +-
gcc/testsuite/g++.dg/pr84492.C | 4 +-
.../g++.dg/template/permissive-error1.C | 20 ++++++
.../g++.dg/template/permissive-error1a.C | 31 +++++++++
.../g++.dg/template/permissive-error1b.C | 30 +++++++++
.../g++.dg/template/permissive-error1c.C | 31 +++++++++
gcc/testsuite/g++.old-deja/g++.pt/crash51.C | 1 -
15 files changed, 240 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/template/permissive-error1.C
create mode 100644 gcc/testsuite/g++.dg/template/permissive-error1a.C
create mode 100644 gcc/testsuite/g++.dg/template/permissive-error1b.C
create mode 100644 gcc/testsuite/g++.dg/template/permissive-error1c.C
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index a52682d835c..44117ba713c 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1420,6 +1420,10 @@ Wtautological-compare
C ObjC C++ ObjC++ Var(warn_tautological_compare) Warning LangEnabledBy(C ObjC
C++ ObjC++,Wall)
Warn if a comparison always evaluates to true or false.
+Wtemplate-body
+C++ ObjC++ Var(warn_template_body) Warning Init(1)
+Diagnose errors when parsing a template.
+
Wtemplate-id-cdtor
C++ ObjC++ Var(warn_template_id_cdtor) Warning
Warn about simple-template-id in a constructor or destructor.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 238d786b067..08ee5895c6a 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7190,6 +7190,13 @@ extern location_t location_of (tree);
extern void qualified_name_lookup_error (tree, tree, tree,
location_t);
+using erroneous_templates_t
+ = hash_map<tree, location_t, simple_hashmap_traits<tree_decl_hash,
location_t>>;
+extern erroneous_templates_t *erroneous_templates;
+
+extern bool cp_seen_error ();
+#define seen_error() cp_seen_error()
+
/* in except.cc */
extern void init_terminate_fn (void);
extern void init_exception_processing (void);
diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
index d80bac822ba..7eab0bf76b4 100644
--- a/gcc/cp/error.cc
+++ b/gcc/cp/error.cc
@@ -165,6 +165,72 @@ class cxx_format_postprocessor : public
format_postprocessor
deferred_printed_type m_type_b;
};
+/* Return the in-scope template that's currently being parsed, or
+ NULL_TREE otherwise. */
+
+static tree
+get_current_template ()
+{
+ if (scope_chain && in_template_context && !current_instantiation ())
+ if (tree ti = get_template_info (current_scope ()))
+ return TI_TEMPLATE (ti);
+
+ return NULL_TREE;
+}
+
+/* A map from TEMPLATE_DECLs that we've determined to be erroneous
+ at parse time to the location of the first error within. */
+
+erroneous_templates_t *erroneous_templates;
+
+/* Callback function diagnostic_context::m_adjust_diagnostic_info.
+
+ Errors issued when parsing a template are automatically treated like
+ permerrors associated with the -Wtemplate-body flag and can be
+ downgraded into warnings accordingly, in which case we'll still
+ issue an error if we later need to instantiate the template. */
+
+static void
+cp_adjust_diagnostic_info (diagnostic_context *context,
+ diagnostic_info *diagnostic)
+{
+ if (diagnostic->kind == DK_ERROR)
+ if (tree tmpl = get_current_template ())
+ {
+ diagnostic->option_index = OPT_Wtemplate_body;
+
+ if (context->m_permissive)
+ diagnostic->kind = DK_WARNING;
+
+ bool existed;
+ location_t &error_loc
+ = hash_map_safe_get_or_insert<false> (erroneous_templates,
+ tmpl, &existed);
+ if (!existed)
+ /* Remember that this template had a parse-time error so
+ that we'll ensure a hard error has been issued upon
+ its instantiation. */
+ error_loc = diagnostic->richloc->get_loc ();
+ }
+}
+
+/* A generalization of seen_error which also returns true if we've
+ permissively downgraded an error to a warning inside a template. */
+
+bool
+cp_seen_error ()
+{
+ if ((seen_error) ())
+ return true;
+
+ if (erroneous_templates)
+ if (tree tmpl = get_current_template ())
+ if (erroneous_templates->get (tmpl))
+ return true;
+
+ return false;
+}
+
/* CONTEXT->printer is a basic pretty printer that was constructed
presumably by diagnostic_initialize(), called early in the
compiler's initialization process (in general_init) Before the FE
@@ -187,6 +253,7 @@ cxx_initialize_diagnostics (diagnostic_context *context)
diagnostic_starter (context) = cp_diagnostic_starter;
/* diagnostic_finalizer is already c_diagnostic_finalizer. */
diagnostic_format_decoder (context) = cp_printer;
+ context->m_adjust_diagnostic_info = cp_adjust_diagnostic_info;
pp_format_postprocessor (pp) = new cxx_format_postprocessor ();
}
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index d1607a06757..7130faf26f5 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -20768,7 +20768,10 @@ finish_module_processing (cpp_reader *reader)
cookie = new module_processing_cookie (cmi_name, tmp_name, fd, e);
- if (errorcount)
+ if (errorcount
+ /* Don't write the module if it contains an erroneous template. */
+ || (erroneous_templates
+ && !erroneous_templates->is_empty ()))
warning_at (state->loc, 0, "not writing module %qs due to errors",
state->get_flatname ());
else if (cookie->out.begin ())
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 77fa5907c3d..b83922a530d 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -12376,6 +12376,18 @@ instantiate_class_template (tree type)
if (! push_tinst_level (type))
return type;
+ if (erroneous_templates && !(seen_error) ())
+ if (location_t *error_loc = erroneous_templates->get (templ))
+ {
+ /* We're trying to instantiate a template pattern containing
+ an error that we've permissively downgraded to a warning.
+ Issue a hard error now to ensure the TU is considered
+ ill-formed. */
+ location_t decl_loc = location_of (templ);
+ error_at (decl_loc, "instantiating erroneous template");
+ inform (*error_loc, "first error appeared here");
+ }
+
int saved_unevaluated_operand = cp_unevaluated_operand;
int saved_inhibit_evaluation_warnings = c_inhibit_evaluation_warnings;
@@ -27291,6 +27303,18 @@ instantiate_decl (tree d, bool defer_ok, bool
expl_inst_class_mem_p)
}
}
+ if (erroneous_templates && !(seen_error) ())
+ if (location_t *error_loc = erroneous_templates->get (td))
+ {
+ /* We're trying to instantiate a template pattern containing
+ an error that we've permissively downgraded to a warning.
+ Issue a hard error now to ensure the TU is considered
+ ill-formed. */
+ location_t decl_loc = location_of (td);
+ error_at (decl_loc, "instantiating erroneous template");
+ inform (*error_loc, "first error appeared here");
+ }
+
code_pattern = DECL_TEMPLATE_RESULT (td);
/* We should never be trying to instantiate a member of a class
diff --git a/gcc/diagnostic.cc b/gcc/diagnostic.cc
index 71d2f44e40c..e90c121cb95 100644
--- a/gcc/diagnostic.cc
+++ b/gcc/diagnostic.cc
@@ -219,6 +219,7 @@ diagnostic_context::initialize (int n_opts)
m_warn_system_headers = false;
m_max_errors = 0;
m_internal_error = nullptr;
+ m_adjust_diagnostic_info = nullptr;
m_text_callbacks.m_begin_diagnostic = default_diagnostic_starter;
m_text_callbacks.m_start_span = default_diagnostic_start_span_fn;
m_text_callbacks.m_end_diagnostic = default_diagnostic_finalizer;
@@ -1416,6 +1417,9 @@ diagnostic_context::report_diagnostic (diagnostic_info
*diagnostic)
if (was_warning && m_inhibit_warnings)
return false;
+ if (m_adjust_diagnostic_info)
+ m_adjust_diagnostic_info (this, diagnostic);
+
if (diagnostic->kind == DK_PEDWARN)
{
diagnostic->kind = m_pedantic_errors ? DK_ERROR : DK_WARNING;
diff --git a/gcc/diagnostic.h b/gcc/diagnostic.h
index 79386ccbf85..d3d77c85e9a 100644
--- a/gcc/diagnostic.h
+++ b/gcc/diagnostic.h
@@ -699,6 +699,10 @@ public:
/* Client hook to report an internal error. */
void (*m_internal_error) (diagnostic_context *, const char *, va_list *);
+ /* Client hook to adjust properties of the given diagnostic that we're
+ about to issue, such as its kind. */
+ void (*m_adjust_diagnostic_info)(diagnostic_context *, diagnostic_info *);
+
private:
/* Client-supplied callbacks for working with options. */
struct {
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index ef2213b4e84..643016a9e93 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -270,7 +270,8 @@ in the following sections.
-Wno-non-template-friend -Wold-style-cast
-Woverloaded-virtual -Wno-pmf-conversions -Wself-move -Wsign-promo
-Wsized-deallocation -Wsuggest-final-methods
--Wsuggest-final-types -Wsuggest-override -Wno-template-id-cdtor
+-Wsuggest-final-types -Wsuggest-override -Wno-template-body
+-Wno-template-id-cdtor
-Wno-terminate -Wno-vexing-parse -Wvirtual-inheritance
-Wno-virtual-move-assign -Wvolatile -Wzero-as-null-pointer-constant}
@@ -4634,6 +4635,14 @@ namespaces, and this may be used to enforce that rule.
The warning is
inactive inside a system header file, such as the STL, so one can still
use the STL. One may also use using directives and qualified names.
+@opindex Wtemplate-body
+@opindex Wno-template-body
+@item -Wno-template-body @r{(C++ and Objective-C++ only)}
+Disable diagnosing errors when parsing a template, and instead issue an
+error only upon instantiation of the template. This flag can also be
+used to downgrade such errors into warnings with @option{Wno-error=} or
+@option{-fpermissive}.
+
@opindex Wtemplate-id-cdtor
@opindex Wno-template-id-cdtor
@item -Wno-template-id-cdtor @r{(C++ and Objective-C++ only)}
@@ -6361,6 +6370,7 @@ that have their own flag:
-Wint-conversion @r{(C and Objective-C only)}
-Wnarrowing @r{(C++ and Objective-C++ only)}
-Wreturn-mismatch @r{(C and Objective-C only)}
+-Wtemplate-body @r{(C++ and Objective-C++ only)}
}
The @option{-fpermissive} option is the default for historic C language
diff --git a/gcc/testsuite/g++.dg/ext/typedef-init.C
b/gcc/testsuite/g++.dg/ext/typedef-init.C
index 153303d217b..47a6642de51 100644
--- a/gcc/testsuite/g++.dg/ext/typedef-init.C
+++ b/gcc/testsuite/g++.dg/ext/typedef-init.C
@@ -32,5 +32,5 @@ struct S {
template<int> void foo()
{
- typedef int i = 0; /* { dg-error "is initialized" } */
+ typedef int i = 0; /* { dg-warning "is initialized" } */
}
diff --git a/gcc/testsuite/g++.dg/pr84492.C b/gcc/testsuite/g++.dg/pr84492.C
index 1a2922096d1..08f368ff29b 100644
--- a/gcc/testsuite/g++.dg/pr84492.C
+++ b/gcc/testsuite/g++.dg/pr84492.C
@@ -3,7 +3,7 @@
template<int> int foo()
{
- return ({ foo; }); // { dg-error "insufficient context" }
+ return ({ foo; }); // { dg-warning "insufficient context" }
}
int bar()
@@ -35,6 +35,6 @@ class C
}
bool g(int)
{
- return ({ g; }); // { dg-error "insufficient context" }
+ return ({ g; }); // { dg-warning "insufficient context" }
}
};
diff --git a/gcc/testsuite/g++.dg/template/permissive-error1.C
b/gcc/testsuite/g++.dg/template/permissive-error1.C
new file mode 100644
index 00000000000..e4536a8b90e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/permissive-error1.C
@@ -0,0 +1,20 @@
+// PR c++/116064
+// { dg-additional-options -fpermissive }
+
+template<class T>
+void f() {
+ const int n = 42;
+ ++n; // { dg-warning "read-only" }
+}
+
+template<class T>
+struct A {
+ void f(typename A::type); // { dg-warning "does not name a type" }
+};
+
+template<class T>
+struct B {
+ void f() {
+ this->g(); // { dg-warning "no member" }
+ }
+};
diff --git a/gcc/testsuite/g++.dg/template/permissive-error1a.C
b/gcc/testsuite/g++.dg/template/permissive-error1a.C
new file mode 100644
index 00000000000..ac47151f0db
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/permissive-error1a.C
@@ -0,0 +1,31 @@
+// PR c++/116064
+// { dg-additional-options -fpermissive }
+// Like permissive-error1.C but verify instantiating the errorneous
+// templates gives an error after all.
+
+template<class T>
+void f() { // { dg-error "instantiating erroneous template" }
+ const int n = 42;
+ ++n; // { dg-warning "read-only variable 'n' .-Wtemplate-body." }
+ // { dg-message "first error appeared here" "" { target *-*-* } .-1 }
+ // { dg-error "read-only variable 'n'\[\n\r\]" "" { target *-*-* } .-2 }
+}
+
+template<class T>
+struct A {
+ void f(typename A::type); // { dg-warning "does not name a type" }
+};
+
+template<class T>
+struct B {
+ void f() {
+ this->g(); // { dg-warning "no member" }
+ }
+};
+
+int main() {
+ f<int>(); // { dg-message "required from here" }
+ A<int> a;
+ B<int> b;
+ b.f();
+}
diff --git a/gcc/testsuite/g++.dg/template/permissive-error1b.C
b/gcc/testsuite/g++.dg/template/permissive-error1b.C
new file mode 100644
index 00000000000..a67b7374625
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/permissive-error1b.C
@@ -0,0 +1,30 @@
+// PR c++/116064
+// { dg-additional-options -Wno-template-body }
+// Like permissive-error1a.C but verify -Wno-template-body suppresses
+// diagnostics.
+
+template<class T>
+void f() { // { dg-error "instantiating erroneous template" }
+ const int n = 42;
+ ++n; // { dg-message "first error appeared here" "" { target *-*-* } }
+ // { dg-error "read-only variable 'n'\[\n\r\]" "" { target *-*-* } .-1 }
+}
+
+template<class T>
+struct A {
+ void f(typename A::type);
+};
+
+template<class T>
+struct B {
+ void f() {
+ this->g();
+ }
+};
+
+int main() {
+ f<int>(); // { dg-message "required from here" }
+ A<int> a;
+ B<int> b;
+ b.f();
+}
diff --git a/gcc/testsuite/g++.dg/template/permissive-error1c.C
b/gcc/testsuite/g++.dg/template/permissive-error1c.C
new file mode 100644
index 00000000000..fd5f26655e5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/permissive-error1c.C
@@ -0,0 +1,31 @@
+// PR c++/116064
+// { dg-additional-options -Wno-error=template-body }
+// Like permissive-error1a.C but verify the diagnostics can also
+// be downgraded via Wno-error=template-body.
+
+template<class T>
+void f() { // { dg-error "instantiating erroneous template" }
+ const int n = 42;
+ ++n; // { dg-warning "read-only variable 'n' .-Wtemplate-body." }
+ // { dg-message "first error appeared here" "" { target *-*-* } .-1 }
+ // { dg-error "read-only variable 'n'\[\n\r\]" "" { target *-*-* } .-2 }
+}
+
+template<class T>
+struct A {
+ void f(typename A::type); // { dg-warning "does not name a type" }
+};
+
+template<class T>
+struct B {
+ void f() {
+ this->g(); // { dg-warning "no member" }
+ }
+};
+
+int main() {
+ f<int>(); // { dg-message "required from here" }
+ A<int> a;
+ B<int> b;
+ b.f();
+}
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash51.C
b/gcc/testsuite/g++.old-deja/g++.pt/crash51.C
index a3fbc17f163..c5cbde521ad 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/crash51.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/crash51.C
@@ -1,5 +1,4 @@
// { dg-do assemble }
-// { dg-options "-fpermissive -w" }
// Origin: Mark Mitchell <m...@codesourcery.com>
char foo[26];
--
2.46.0.39.g891ee3b9db
