[Ping v2] [PATCH 1/1] gdb: Enable complete to show members of anonymous classes/structs.

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

*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

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