RE: [Ping v3] [PATCH 1/1] gdb: Enable complete to show members of anonymous classes/structs.

["Willgerodt, Felix" <felix.willgerodt@intel.com>]

*Ping* v3

Thanks,
Felix

> -----Original Message-----
> From: Willgerodt, Felix
> Sent: Montag, 17. Oktober 2022 10:34
> To: gdb-patches@sourceware.org
> Subject: [Ping v2] [PATCH 1/1] gdb: Enable complete to show members of
> anonymous classes/structs.
> 
> *Ping* v2
> 
> Thanks,
> Felix
> 
> > -----Original Message-----
> > From: Willgerodt, Felix
> > Sent: Dienstag, 20. September 2022 11:49
> > To: gdb-patches@sourceware.org
> > Subject: [Ping] [PATCH 1/1] gdb: Enable complete to show members of
> > anonymous classes/structs.
> >
> > *Ping*
> >
> > One non-maintainer has "+1"-ed this:
> > https://sourceware.org/pipermail/gdb-patches/2022-
> > September/191705.html
> >
> > But there is still the open question, if the current code is actually right
> > filtering for LOC_TYPEDEF
> > (or for LOC_COMPUTED now). Any hints are appreciated.
> >
> > Thanks,
> > Felix
> >
> > > -----Original Message-----
> > > From: Willgerodt, Felix <felix.willgerodt@intel.com>
> > > Sent: Dienstag, 6. September 2022 09:22
> > > To: gdb-patches@sourceware.org
> > > Cc: Willgerodt, Felix <felix.willgerodt@intel.com>
> > > Subject: [PATCH 1/1] gdb: Enable complete to show members of
> > anonymous
> > > classes/structs.
> > >
> > > This problem shows with anonymous structs/classes:
> > >
> > > ~~~
> > >   struct {
> > >     private:
> > >       int unique_name_foo = 5;
> > >     public:
> > >       int get() { return unique_name_foo; } /* breakpoint.  */
> > >   } a;
> > > ~~~
> > >
> > > Before:
> > >
> > > ~~~
> > > (gdb) p unique_name_foo
> > > $1 = 5
> > > (gdb) complete p unique_name_fo
> > > (gdb)
> > >
> > > ~~~
> > >
> > > After:
> > >
> > > ~~~
> > > (gdb) p unique_name_foo
> > > $1 = 5
> > > (gdb) complete p unique_name_fo
> > > p unique_name_foo
> > > (gdb)
> > > ~~~
> > >
> > > As we are able to print the member we should be able to complete on it.
> > > GDB doesn't look at "this" and its members for complete, while it does
> > > when printing.  So I tried fixing that.
> > > I saw that "this" is always represented as a PTR type with the symbol
> > > class LOC_COMPUTED (with g++ 11.3.1, clang++ 10.0.1 and icpx 2022.1).
> > >
> > > Not knowing too much about LOC_COMPUTED, I am assuming that this is
> > the
> > > right
> > > symbol class for this case and that we should adjust
> > > completion_list_add_fields() for it.
> > > But it could very well be that I missed something.  Any comments
> > welcome!
> > > ---
> > >  gdb/symtab.c                          | 18 ++++++++++++------
> > >  gdb/testsuite/gdb.cp/cpcompletion.exp | 16 +++++++++++++---
> > >  gdb/testsuite/gdb.cp/pr9594.cc        |  9 ++++++---
> > >  3 files changed, 31 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/gdb/symtab.c b/gdb/symtab.c
> > > index 40887f59d1f..6edeb4ea9db 100644
> > > --- a/gdb/symtab.c
> > > +++ b/gdb/symtab.c
> > > @@ -5688,14 +5688,20 @@ completion_list_add_fields
> > (completion_tracker
> > > &tracker,
> > >  			    const lookup_name_info &lookup_name,
> > >  			    const char *text, const char *word)
> > >  {
> > > -  if (sym->aclass () == LOC_TYPEDEF)
> > > +  struct type *t = sym->type ();
> > > +
> > > +  if (sym->aclass () == LOC_TYPEDEF
> > > +      || (sym->aclass () == LOC_COMPUTED && t->code () ==
> > > TYPE_CODE_PTR))
> > >      {
> > > -      struct type *t = sym->type ();
> > > -      enum type_code c = t->code ();
> > > -      int j;
> > > +      /* Anonymous classes/structs are often/always represented as a
> > > +	 pointer with LOC_COMPUTED.  Since we also want to show their
> > > +	 fields as a completion result (as we can print them) we resolve
> > > +	 their target type.  */
> > > +      if (t->code () == TYPE_CODE_PTR)
> > > +	t = TYPE_TARGET_TYPE (t);
> > >
> > > -      if (c == TYPE_CODE_UNION || c == TYPE_CODE_STRUCT)
> > > -	for (j = TYPE_N_BASECLASSES (t); j < t->num_fields (); j++)
> > > +      if (t->code () == TYPE_CODE_UNION || t->code () ==
> > > TYPE_CODE_STRUCT)
> > > +	for (int j = TYPE_N_BASECLASSES (t); j < t->num_fields (); j++)
> > >  	  if (t->field (j).name ())
> > >  	    completion_list_add_name (tracker, sym->language (),
> > >  				      t->field (j).name (),
> > > diff --git a/gdb/testsuite/gdb.cp/cpcompletion.exp
> > > b/gdb/testsuite/gdb.cp/cpcompletion.exp
> > > index d19ac9c1b69..07ec936e95a 100644
> > > --- a/gdb/testsuite/gdb.cp/cpcompletion.exp
> > > +++ b/gdb/testsuite/gdb.cp/cpcompletion.exp
> > > @@ -76,10 +76,11 @@ test_class_complete Foo F "complete class methods
> > > beginning with F" \
> > >
> > >  # The tests below depend on the current code scope.
> > >
> > > -set bp_location [gdb_get_line_number "Set breakpoint here" ${srcfile}]
> > > +set bp_1 [gdb_get_line_number "BP1" ${srcfile}]
> > > +set bp_2 [gdb_get_line_number "BP2" ${srcfile}]
> > >
> > > -if {![runto "${srcfile}:$bp_location"]} {
> > > -    perror "test suppressed"
> > > +if {![runto "${srcfile}:$bp_1"]} {
> > > +    untested "failed to run to first breakpoint"
> > >      return
> > >  }
> > >
> > > @@ -135,3 +136,12 @@ with_test_prefix "expression with namespace" {
> > >      # Add a disambiguating character and we get a unique completion.
> > >      test_gdb_complete_unique "p Test_NS::f" "p Test_NS::foo"
> > >  }
> > > +
> > > +# Test completion when stopped in a method of an anonymous struct.
> > > +gdb_breakpoint "$srcfile:$bp_2"
> > > +gdb_continue_to_breakpoint "continue to second bp"
> > ".*$srcfile:$bp_2.*"
> > > +
> > > +# We should be able to complete on the members.  We are able to print
> > > +# them after all.
> > > +gdb_test "p unique_name_foo" "= 5"
> > > +gdb_test "complete p unique_name_fo" "p unique_name_foo"
> > > diff --git a/gdb/testsuite/gdb.cp/pr9594.cc
> > b/gdb/testsuite/gdb.cp/pr9594.cc
> > > index 54ddaafc0ca..a3823f9b84f 100644
> > > --- a/gdb/testsuite/gdb.cp/pr9594.cc
> > > +++ b/gdb/testsuite/gdb.cp/pr9594.cc
> > > @@ -56,10 +56,13 @@ int main ()
> > >  {
> > >    // Anonymous struct with method.
> > >    struct {
> > > -    int get() { return 5; }
> > > +    private:
> > > +      int unique_name_foo = 5;
> > > +    public:
> > > +      int get() { return unique_name_foo; } /* BP2.  */
> > >    } a;
> > >    Foo foo1;
> > > -  foo1.set_foo (42);		// Set breakpoint here.
> > > -  a.get();			// Prevent compiler from throwing 'a' away.
> > > +  foo1.set_foo (42);		/* BP1.  */
> > > +  a.get ();
> > >    return 0;
> > >  }
> > > --
> > > 2.34.3

Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva  
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928