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

[Willgerodt, Felix]

*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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