[PING][PATCH][gdb/symtab] Fix language of duplicate static minimal symbol

[Tom de Vries <tdevries at suse dot de>]

On 10/31/18 10:09 AM, Tom de Vries wrote:
> On 10/30/18 10:21 PM, Keith Seitz wrote:
>> On 10/30/18 12:11 PM, Tom de Vries wrote:
>>> However, when we use gdb to print info on foo, both foos are listed, but we
>>> get one symbol mangled and one symbol demangled:
>>> ...
>>> $ gdb ./a.out -batch -ex "info func foo"
>>> All functions matching regular expression "foo":
>>>
>>> Non-debugging symbols:
>>> 0x00000000004004c7  foo()
>>> 0x00000000004004dd  _ZL3foov
>>> ...
>>>
>> Good catch!
>>>> Build and reg-tested on x86_64-linux.
>>> OK for trunk?
>> I have just a few comments.
>>
>>> 2018-10-30  Tom de Vries  <tdevries@suse.de>
>>>
>>> 	* symtab.c (symbol_set_names): Call symbol_find_demangled_name
>>> 	unconditionally, to get the language of the symbol.
>> s/get/set/ ? When reading the patch, I originally wondered how that would help,
>> but symbol_find_demangled_name actually *sets* the gsymbol's language if
>> it is language_auto.
>>
> Typo fixed.
> 
>>> 	* gdb.base/msym.c: New test.
>>> 	* gdb.base/msym.exp: New file.
>>> 	* gdb.base/msym_main.c: New test.
>> These entries should be listed under the testsuite ChangeLog, like:
>>
>> testsuite/ChangeLog:
>> YYYY-MM-DD ....
>>
>> 	* gdb.xyz/file1.c: ...
>> 	* gdb.xyz/file1.exp: ....
>>
>> [https://sourceware.org/gdb/wiki/ContributionChecklist#Properly_Formatted_GNU_ChangeLog]
>>
> I have a pre-commit script (for both gcc and gdb) that uses this format,
> and puts ChangeLog hunks in the correct ChangeLog file ( more detail
> here: https://sourceware.org/ml/gdb-patches/2018-06/msg00351.html ).
> Sofar this format has been acceptable for maintainers.
> 
>> "msym.c" et al aren't particularly descriptive, though. Can we devise a better,
>> more explicit name? Something along the lines of "multiple-language-msyms.exp".
>> It's long, but it describes things better. [I'm not saying you should use
>> this name, but something other than just "msym.{c,exp}".]
>>
> Renamed to msym-lang.exp et al.
> 
>> Sorry, some of that is kinda nitpicky.
>>
> Np, I'm still kinda new to gdb, all input appreciated.
> 
>>> diff --git a/gdb/symtab.c b/gdb/symtab.c
>>> index cd27a75e8c..481428f733 100644
>>> --- a/gdb/symtab.c
>>> +++ b/gdb/symtab.c
>>> @@ -818,6 +818,10 @@ symbol_set_names (struct general_symbol_info *gsymbol,
>>>    else
>>>      linkage_name_copy = linkage_name;
>>>  
>>> +  /* Set the symbol language.  */
>>> +  char *demangled_name = symbol_find_demangled_name (gsymbol,
>>> +						     linkage_name_copy);
>>> +
>>>    entry.mangled = linkage_name_copy;
>>>    slot = ((struct demangled_name_entry **)
>>>  	  htab_find_slot (per_bfd->demangled_names_hash,
>> symbol_find_demangled_name returns a malloc'd string which will leak here unless
>> the code goes through the branch. You'll need to save the result into a
>> unique_xmalloc_ptr and adjust the code accordingly.
>>
> Done, thanks for pointing that out.
> 
>> Otherwise, LGTM. Thanks very much for the patch.
>>
> And thanks for the review.
> 
> Re-tested as attached.
> 

Ping. Ok for trunk?

Thanks,
- Tom

> 0001-gdb-symtab-Fix-language-of-duplicate-static-minimal-symbol.patch
> 
> [gdb/symtab] Fix language of duplicate static minimal symbol
> 
> Consider a test-case with source files msym.c:
> ...
> static int foo (void) { return 1; }
> ...
> and msym_main.c:
> ...
> static int foo (void) { return 2; }
> int main (void) { return 0; }
> ..
> compiled as c++ with minimal symbols:
> ...
> $ g++ msym_main.c msym.c
> ...
> 
> With objdump -x we find the two foo symbols prefixed with their corresponding
> files in the symbol table:
> ...
> 0000000000000000 l    df *ABS*  0000000000000000              msym_main.c
> 00000000004004c7 l     F .text  000000000000000b              _ZL3foov
> 0000000000000000 l    df *ABS*  0000000000000000              msym.c
> 00000000004004dd l     F .text  000000000000000b              _ZL3foov
> ...
> 
> However, when we use gdb to print info on foo, both foos are listed, but we
> get one symbol mangled and one symbol demangled:
> ...
> $ gdb ./a.out -batch -ex "info func foo"
> All functions matching regular expression "foo":
> 
> Non-debugging symbols:
> 0x00000000004004c7  foo()
> 0x00000000004004dd  _ZL3foov
> ...
> 
> During minimal symbol reading symbol_set_names is called for each symbol.
> 
> First, it's called with foo from msym.c, an entry is created in
> per_bfd->demangled_names_hash and symbol_find_demangled_name is called, which
> has the side effect of setting the language of the symbol to language_cplus.
> 
> Then, it's called with foo from msym_main.c.  Since
> per_bfd->demangled_names_hash already has an entry for that name,
> symbol_find_demangled_name is not called, and the language of the symbol
> remains language_auto.
> 
> Fix this by doing the symbol_find_demangled_name call unconditionally.
> 
> Build and reg-tested on x86_64-linux.
> 
> 2018-10-30  Tom de Vries  <tdevries@suse.de>
> 
> 	* symtab.c (symbol_set_names): Call symbol_find_demangled_name
> 	unconditionally, to set the language of the symbol.  Manage freeing
> 	returned pointer using gdb::unique_xmalloc_ptr.
> 
> 	* gdb.base/msym-lang.c: New test.
> 	* gdb.base/msym-lang.exp: New file.
> 	* gdb.base/msym-lang-main.c: New test.
> 
> ---
>  gdb/symtab.c                            | 14 +++++++-------
>  gdb/testsuite/gdb.base/msym-lang-main.c | 28 ++++++++++++++++++++++++++++
>  gdb/testsuite/gdb.base/msym-lang.c      | 22 ++++++++++++++++++++++
>  gdb/testsuite/gdb.base/msym-lang.exp    | 25 +++++++++++++++++++++++++
>  4 files changed, 82 insertions(+), 7 deletions(-)
> 
> diff --git a/gdb/symtab.c b/gdb/symtab.c
> index cd27a75e8c..aee4c0c710 100644
> --- a/gdb/symtab.c
> +++ b/gdb/symtab.c
> @@ -818,6 +818,11 @@ symbol_set_names (struct general_symbol_info *gsymbol,
>    else
>      linkage_name_copy = linkage_name;
>  
> +  /* Set the symbol language.  */
> +  char *demangled_name_ptr
> +    = symbol_find_demangled_name (gsymbol, linkage_name_copy);
> +  gdb::unique_xmalloc_ptr<char> demangled_name (demangled_name_ptr);
> +
>    entry.mangled = linkage_name_copy;
>    slot = ((struct demangled_name_entry **)
>  	  htab_find_slot (per_bfd->demangled_names_hash,
> @@ -830,9 +835,7 @@ symbol_set_names (struct general_symbol_info *gsymbol,
>        || (gsymbol->language == language_go
>  	  && (*slot)->demangled[0] == '\0'))
>      {
> -      char *demangled_name = symbol_find_demangled_name (gsymbol,
> -							 linkage_name_copy);
> -      int demangled_len = demangled_name ? strlen (demangled_name) : 0;
> +      int demangled_len = demangled_name ? strlen (demangled_name.get ()) : 0;
>  
>        /* Suppose we have demangled_name==NULL, copy_name==0, and
>  	 linkage_name_copy==linkage_name.  In this case, we already have the
> @@ -870,10 +873,7 @@ symbol_set_names (struct general_symbol_info *gsymbol,
>  	}
>  
>        if (demangled_name != NULL)
> -	{
> -	  strcpy ((*slot)->demangled, demangled_name);
> -	  xfree (demangled_name);
> -	}
> +	strcpy ((*slot)->demangled, demangled_name.get());
>        else
>  	(*slot)->demangled[0] = '\0';
>      }
> diff --git a/gdb/testsuite/gdb.base/msym-lang-main.c b/gdb/testsuite/gdb.base/msym-lang-main.c
> new file mode 100644
> index 0000000000..f093f71ca4
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/msym-lang-main.c
> @@ -0,0 +1,28 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2018 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +static int
> +foo (void)
> +{
> +  return 2;
> +}
> +
> +int
> +main (void)
> +{
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.base/msym-lang.c b/gdb/testsuite/gdb.base/msym-lang.c
> new file mode 100644
> index 0000000000..c9610154dd
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/msym-lang.c
> @@ -0,0 +1,22 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2018 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +static int
> +foo (void)
> +{
> +  return 1;
> +}
> diff --git a/gdb/testsuite/gdb.base/msym-lang.exp b/gdb/testsuite/gdb.base/msym-lang.exp
> new file mode 100644
> index 0000000000..993225c9d6
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/msym-lang.exp
> @@ -0,0 +1,25 @@
> +# Copyright (C) 2018 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +standard_testfile msym-lang-main.c msym-lang.c
> +
> +if {[prepare_for_testing "failed to prepare" $testfile [list $srcfile $srcfile2] \
> +	 {c++}]} {
> +    return -1
> +}
> +
> +clean_restart ${testfile}
> +
> +gdb_test "info func foo" ".* foo\\(\\).* foo\\(\\).*"
>