Symbols with the same zero value are not aliases

When looking at ELF file of the ET_REL kind (i.e, relocatable object
files), several kinds of symbols (for instance weak symbols) can have
the symbol value zero.  Although they have the same value, the fact
that that value is zero prevents us from considering those symbols as
being aliases.

Libabigail was wrongly considering those symbols with value zero as
being aliases.  So, in practice, it was considering all WEAK symbols
as being aliases, because the value of a weak symbols is zero.

When comparing two binaries originating from the same source code, one
compiled with g++ and the other one compiled with clang++, abidiff was
thus reporting spurious function aliases changes due to this issue.

Note that the two binaries in question come from the bug PR21486.
Comparing them using abidiff exhibits several other issues that were
fixed in previous commits, such as

 - Reporting changes about top cv qualifier changes on function
 parameter types.
 - Not supporting ELF symbol visibility

	* src/abg-dwarf-reader.cc (load_symbol_maps_from_symtab_section):
	Do not consider symbols with zero value as being aliases.
	* tests/data/test-diff-filter/test20-inline-report-0.txt: Adjust.
	* tests/data/test-diff-filter/test20-inline-report-1.txt:
	Likewise.
	* test-diff-filter/test41-PR21486-abg-writer.gcc.o: New test
	binary input.
	* tests/data/test-diff-filter/test41-PR21486-abg-writer.llvm.o:
	Likewise.
	* tests/data/Makefile.am: Add the new test material to source
	distribution.
	* tests/test-diff-filter.cc (in_out_specs): Run the test harness
	on the new test input above.
	* tests/data/test-diff-dwarf/test5-report.txt: Adjust.
	* tests/data/test-diff-filter/test9-report.txt: Adjust.
	* tests/data/test-diff-filter/test20-inline-report-0.txt: Adjust.
	* tests/data/test-diff-filter/test20-inline-report-1.txt: Adjust.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>

diff --git a/src/abg-dwarf-reader.cc b/src/abg-dwarf-reader.cc
index f6faa34..01e83fb 100644 (file)
--- a/src/abg-dwarf-reader.cc
+++ b/src/abg-dwarf-reader.cc
@@ -6682,7 +6682,7 @@ public:
                    fun_addr_sym_map_->find(sym->st_value);
                  if (it == fun_addr_sym_map_->end())
                    (*fun_addr_sym_map_)[sym->st_value] = symbol;
-                 else
+                 else  if (sym->st_value != 0)
                    it->second->get_main_symbol()->add_alias(symbol);
 
                  if (is_ppc64)

diff --git a/tests/data/Makefile.am b/tests/data/Makefile.am
index c7e405e..bc10730 100644 (file)
--- a/tests/data/Makefile.am
+++ b/tests/data/Makefile.am
@@ -625,6 +625,9 @@ test-diff-filter/libtest40-v1.so \
 test-diff-filter/test40-report-0.txt \
 test-diff-filter/test40-v0.cc \
 test-diff-filter/test40-v1.cc \
+test-diff-filter/test41-PR21486-abg-writer.gcc.o \
+test-diff-filter/test41-PR21486-abg-writer.llvm.o \
+test-diff-filter/test41-report-0.txt \
 \
 test-diff-suppr/test0-type-suppr-v0.cc \
 test-diff-suppr/test0-type-suppr-v1.cc \

diff --git a/tests/data/test-diff-dwarf/test5-report.txt b/tests/data/test-diff-dwarf/test5-report.txt
index 2f099db..c8c9830 100644 (file)
--- a/tests/data/test-diff-dwarf/test5-report.txt
+++ b/tests/data/test-diff-dwarf/test5-report.txt
@@ -4,8 +4,6 @@ Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
 1 function with some indirect sub-type change:
 
   [C]'function C0 foo()' has some indirect sub-type changes:
-    Please note that the symbol of this function is _ZN2C0C2Ev
-     and it aliases symbols: _ZN2C0C1Ev, _Z3foov
     return type changed:
       entity changed from 'class C0' to compatible type 'typedef c0_type'
         type size hasn't changed

diff --git a/tests/data/test-diff-filter/test20-inline-report-0.txt b/tests/data/test-diff-filter/test20-inline-report-0.txt
index e69de29..9666a8f 100644 (file)
--- a/tests/data/test-diff-filter/test20-inline-report-0.txt
+++ b/tests/data/test-diff-filter/test20-inline-report-0.txt
@@ -0,0 +1,3 @@
+Functions changes summary: 0 Removed, 0 Changed (1 filtered out), 0 Added function
+Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
+

diff --git a/tests/data/test-diff-filter/test20-inline-report-1.txt b/tests/data/test-diff-filter/test20-inline-report-1.txt
index e69de29..2abdae7 100644 (file)
--- a/tests/data/test-diff-filter/test20-inline-report-1.txt
+++ b/tests/data/test-diff-filter/test20-inline-report-1.txt
@@ -0,0 +1,9 @@
+Functions changes summary: 0 Removed, 1 Changed, 0 Added function
+Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
+
+1 function with some indirect sub-type change:
+
+  [C]'function int bar()' has some indirect sub-type changes:
+    'function int bar() {_ZN1S3fooEv}' now becomes 'method int S::foo() {_ZN1S3fooEv}'
+
+

diff --git a/tests/data/test-diff-filter/test41-PR21486-abg-writer.gcc.o b/tests/data/test-diff-filter/test41-PR21486-abg-writer.gcc.o
new file mode 100644 (file)
index 0000000..2927c24
Binary files /dev/null and b/tests/data/test-diff-filter/test41-PR21486-abg-writer.gcc.o differ

diff --git a/tests/data/test-diff-filter/test41-PR21486-abg-writer.llvm.o b/tests/data/test-diff-filter/test41-PR21486-abg-writer.llvm.o
new file mode 100644 (file)
index 0000000..1a9f8f9
Binary files /dev/null and b/tests/data/test-diff-filter/test41-PR21486-abg-writer.llvm.o differ

diff --git a/tests/data/test-diff-filter/test41-report-0.txt b/tests/data/test-diff-filter/test41-report-0.txt
new file mode 100644 (file)
index 0000000..b167de0
--- /dev/null
+++ b/tests/data/test-diff-filter/test41-report-0.txt
@@ -0,0 +1,42 @@
+Functions changes summary: 0 Removed, 0 Changed (4 filtered out), 1 Added function
+Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
+Function symbols changes summary: 12 Removed, 15 Added function symbols not referenced by debug info
+Variable symbols changes summary: 0 Removed, 0 Added variable symbol not referenced by debug info
+
+1 Added function:
+
+  'function bool abigail::xml_writer::annotate(const abigail::ir::function_type_sptr&, abigail::xml_writer::write_context&, unsigned int)'    {_ZN7abigail10xml_writer13write_context10sort_typesERKSt6vectorINSt3tr110shared_ptrINS_2ir13function_typeEEESaIS7_EERS2_INS4_INS5_9type_baseEEESaISD_EE}
+
+12 Removed function symbols not referenced by debug info:
+
+  _ZN7abigail10xml_writer13write_context32record_decl_only_type_as_emittedEPNS_2ir9type_baseE
+  _ZN7abigail10xml_writer13write_contextC1EPKNS_2ir11environmentERSob
+  _ZN7abigail10xml_writer13write_contextD1Ev
+  _ZNKSt3tr18__detail20_Prime_rehash_policy14_M_need_rehashEmmm
+  _ZNSt11_Deque_baseIjSaIjEED1Ev
+  _ZNSt11_Deque_baseIjSaIjEED2Ev
+  _ZNSt3tr114__shared_countILN9__gnu_cxx12_Lock_policyE2EEaSERKS3_
+  _ZNSt3tr116_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EE10_M_releaseEv
+  _ZNSt5dequeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EE12emplace_backIJS5_EEEvDpOT_
+  _ZNSt5dequeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EE16_M_push_back_auxIJS5_EEEvDpOT_
+  _ZNSt5dequeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EED1Ev
+  _ZNSt5dequeIjSaIjEE16_M_push_back_auxIJRKjEEEvDpOT_
+
+15 Added function symbols not referenced by debug info:
+
+  _ZN7abigail10xml_writer13write_context10sort_typesERNSt3tr113unordered_mapIPNS_2ir9type_baseENS_15interned_stringENS0_11type_hasherENS_10diff_utils19deep_ptr_eq_functorESaISt4pairIKS6_S7_EEEERSt6vectorIS6_SaIS6_EE
+  _ZN7abigail10xml_writer13write_context18get_id_for_fn_tmplB5cxx11ERKNSt3tr110shared_ptrINS_2ir14function_tdeclEEE
+  _ZN7abigail10xml_writer13write_context21get_id_for_class_tmplB5cxx11ERKNSt3tr110shared_ptrINS_2ir11class_tdeclEEE
+  _ZN7abigail10xml_writer13write_context25record_type_id_as_emittedERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE
+  _ZNSt11_Deque_baseINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EE15_M_create_nodesEPPS5_S9_
+  _ZNSt11_Deque_baseIjSaIjEE15_M_create_nodesEPPjS3_
+  _ZNSt20__uninitialized_copyILb0EE13__uninit_copyISt15_Deque_iteratorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS8_PS9_ES2_IS8_RS8_PS8_EEET0_T_SH_SG_
+  _ZNSt3tr116_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EED2Ev
+  _ZNSt3tr132__enable_shared_from_this_helperILN9__gnu_cxx12_Lock_policyE2EEEvRKNS_14__shared_countIXT_EEEz
+  _ZNSt5dequeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EE16_M_push_back_auxERKS5_
+  _ZNSt5dequeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EE17_M_reallocate_mapEmb
+  _ZNSt5dequeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EE19_M_destroy_data_auxESt15_Deque_iteratorIS5_RS5_PS5_ESB_
+  _ZNSt5dequeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS5_EEC2ERKS7_
+  _ZNSt5dequeIjSaIjEE17_M_reallocate_mapEmb
+  _ZNSt5stackINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt5dequeIS5_SaIS5_EEE4pushERKS5_
+

diff --git a/tests/data/test-diff-filter/test9-report.txt b/tests/data/test-diff-filter/test9-report.txt
index a600efe..94b973b 100644 (file)
--- a/tests/data/test-diff-filter/test9-report.txt
+++ b/tests/data/test-diff-filter/test9-report.txt
@@ -1,5 +1,7 @@
 Functions changes summary: 0 Removed, 1 Changed, 2 Added functions
 Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
+Function symbols changes summary: 0 Removed, 1 Added function symbol not referenced by debug info
+Variable symbols changes summary: 0 Removed, 0 Added variable symbol not referenced by debug info
 
 2 Added functions:
 
@@ -16,3 +18,7 @@ Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
           'int S::m0', at offset 0 (in bits)
 
 
+1 Added function symbol not referenced by debug info:
+
+  _ZN1SC1Ev
+

diff --git a/tests/test-diff-filter.cc b/tests/test-diff-filter.cc
index 4254aaa..1b8e38d 100644 (file)
--- a/tests/test-diff-filter.cc
+++ b/tests/test-diff-filter.cc
@@ -471,6 +471,13 @@ InOutSpec in_out_specs[] =
     "data/test-diff-filter/test40-report-0.txt",
     "output/test-diff-filter/test40-report-0.txt",
   },
+  {
+    "data/test-diff-filter/test41-PR21486-abg-writer.gcc.o",
+    "data/test-diff-filter/test41-PR21486-abg-writer.llvm.o",
+    "--no-default-suppression",
+    "data/test-diff-filter/test41-report-0.txt",
+    "output/test-diff-filter/test41-report-0.txt",
+  },
   // This should be the last entry
   {NULL, NULL, NULL, NULL, NULL}
 };