[applied] Bug 29912 - Better support an ELF symbol alias that designates several functions

diff --git a/include/abg-corpus.h b/include/abg-corpus.h
index 090bad14..cbc7ec24 100644
--- a/include/abg-corpus.h
+++ b/include/abg-corpus.h
@@ -218,7 +218,7 @@  public:
   virtual const functions&
   get_functions() const;
 
-  const vector<function_decl*>*
+  const std::unordered_set<function_decl*>*
   lookup_functions(const string& id) const;
 
   void
@@ -302,13 +302,13 @@  operator&=(corpus::origin &l, corpus::origin r);
 /// parameters needed.
 class corpus::exported_decls_builder
 {
-  class priv;
-  std::unique_ptr<priv> priv_;
-
   // Forbid default construction.
   exported_decls_builder();
 
 public:
+  class priv;
+  std::unique_ptr<priv> priv_;
+
   friend class corpus;
 
   exported_decls_builder(functions& fns,
@@ -327,6 +327,9 @@  public:
   functions&
   exported_functions();
 
+  std::unordered_set<function_decl*>*
+  fn_id_maps_to_several_fns(function_decl*);
+
   const variables&
   exported_variables() const;
 
@@ -334,7 +337,7 @@  public:
   exported_variables();
 
   void
-  maybe_add_fn_to_exported_fns(const function_decl*);
+  maybe_add_fn_to_exported_fns(function_decl*);
 
   void
   maybe_add_var_to_exported_vars(const var_decl*);
diff --git a/include/abg-fwd.h b/include/abg-fwd.h
index fc3f4374..747a625c 100644
--- a/include/abg-fwd.h
+++ b/include/abg-fwd.h
@@ -1004,6 +1004,9 @@  get_function_type_name(const function_type*, bool internal = false);
 interned_string
 get_function_type_name(const function_type&, bool internal = false);
 
+interned_string
+get_function_id_or_pretty_representation(function_decl *fn);
+
 interned_string
 get_method_type_name(const method_type_sptr&, bool internal = false);
 
diff --git a/include/abg-ir.h b/include/abg-ir.h
index 0ca8afcf..6d81097a 100644
--- a/include/abg-ir.h
+++ b/include/abg-ir.h
@@ -1094,6 +1094,9 @@  public:
   elf_symbol_sptr
   get_alias_which_equals(const elf_symbol& other) const;
 
+  elf_symbol_sptr
+  get_alias_with_default_symbol_version() const;
+
   string
   get_aliases_id_string(const string_elf_symbols_map_type& symtab,
 			bool include_symbol_itself = true) const;
diff --git a/src/abg-comparison.cc b/src/abg-comparison.cc
index 1533d9d1..baae56a3 100644
--- a/src/abg-comparison.cc
+++ b/src/abg-comparison.cc
@@ -9036,7 +9036,7 @@  corpus_diff::priv::ensure_lookup_tables_populated()
 	ABG_ASSERT(i < first_->get_functions().size());
 
 	function_decl* deleted_fn = first_->get_functions()[i];
-	string n = deleted_fn->get_id();
+	string n = get_function_id_or_pretty_representation(deleted_fn);
 	ABG_ASSERT(!n.empty());
 	// The below is commented out because there can be several
 	// functions with the same ID in the corpus.  So several
@@ -9056,7 +9056,7 @@  corpus_diff::priv::ensure_lookup_tables_populated()
 	  {
 	    unsigned i = *iit;
 	    function_decl* added_fn = second_->get_functions()[i];
-	    string n = added_fn->get_id();
+	    string n = get_function_id_or_pretty_representation(added_fn);
 	    ABG_ASSERT(!n.empty());
 	    // The below is commented out because there can be several
 	    // functions with the same ID in the corpus.  So several
diff --git a/src/abg-corpus-priv.h b/src/abg-corpus-priv.h
index 422b7870..412db377 100644
--- a/src/abg-corpus-priv.h
+++ b/src/abg-corpus-priv.h
@@ -40,6 +40,12 @@  typedef vector<regex_t_sptr> regex_t_sptrs_type;
 /// Convenience typedef for a hash map which key is a string and which
 /// data is a vector of abigail::ir::function_decl*
 typedef unordered_map<string, vector<function_decl*> > str_fn_ptrs_map_type;
+
+/// Convenience typedef for a hash map which key is a string and which
+/// data is a set of abigail::ir::function_decl*
+typedef unordered_map<string, std::unordered_set<function_decl*> >
+str_fn_ptr_set_map_type;
+
 /// Convenience typedef for a hash map which key is a string and
 /// which data is an abigail::ir::var_decl*.
 typedef unordered_map<string, var_decl*> str_var_ptr_map_type;
@@ -63,7 +69,7 @@  class corpus::exported_decls_builder::priv
   // template parameters of the second instantiation are just typedefs
   // of the first instantiation, for instance.  So there can be cases
   // where one ID appertains to more than one function.
-  str_fn_ptrs_map_type	id_fns_map_;
+  str_fn_ptr_set_map_type	id_fns_map_;
   str_var_ptr_map_type	id_var_map_;
   strings_type&	fns_suppress_regexps_;
   regex_t_sptrs_type	compiled_fns_suppress_regexp_;
@@ -197,7 +203,7 @@  public:
   ///
   /// @return a map which key is a string and which data is a pointer
   /// to a function.
-  const str_fn_ptrs_map_type&
+  const str_fn_ptr_set_map_type&
   id_fns_map() const
   {return id_fns_map_;}
 
@@ -210,7 +216,7 @@  public:
   ///
   /// @return a map which key is a string and which data is a pointer
   /// to a function.
-  str_fn_ptrs_map_type&
+  str_fn_ptr_set_map_type&
   id_fns_map()
   {return id_fns_map_;}
 
@@ -267,11 +273,11 @@  public:
   ///
   /// @return the pointer to the vector of functions with ID @p fn_id,
   /// or nil if no function with that ID exists.
-  vector<function_decl*>*
+  std::unordered_set<function_decl*>*
   fn_id_is_in_id_fns_map(const string& fn_id)
   {
-    str_fn_ptrs_map_type& m = id_fns_map();
-    str_fn_ptrs_map_type::iterator i = m.find(fn_id);
+    str_fn_ptr_set_map_type& m = id_fns_map();
+    str_fn_ptr_set_map_type::iterator i = m.find(fn_id);
     if (i == m.end())
       return 0;
     return &i->second;
@@ -286,47 +292,87 @@  public:
   /// @p fn, that are present in the id-functions map, or nil if no
   /// function with the same ID as @p fn is present in the
   /// id-functions map.
-  vector<function_decl*>*
+  std::unordered_set<function_decl*>*
   fn_id_is_in_id_fns_map(const function_decl* fn)
   {
     string fn_id = fn->get_id();
     return fn_id_is_in_id_fns_map(fn_id);
   }
 
-  /// Test if a given function is present in a vector of functions.
+  /// Test if a given function is present in a set of functions.
   ///
   /// The function compares the ID and the qualified name of
   /// functions.
   ///
   /// @param fn the function to consider.
   ///
-  /// @parm fns the vector of functions to consider.
+  /// @parm fns the set of functions to consider.
   static bool
-  fn_is_in_fns(const function_decl* fn, const vector<function_decl*>& fns)
+  fn_is_in_fns(function_decl* fn,
+	       const std::unordered_set<function_decl*>& fns)
   {
     if (fns.empty())
       return false;
 
+    if (fns.find(fn) != fns.end())
+      return true;
+
     const string fn_id = fn->get_id();
-    for (vector<function_decl*>::const_iterator i = fns.begin();
-	 i != fns.end();
-	 ++i)
-      if ((*i)->get_id() == fn_id
-	  && (*i)->get_qualified_name() == fn->get_qualified_name())
+    for (const auto f : fns)
+      if (f->get_id() == fn_id
+	  && f->get_qualified_name() == fn->get_qualified_name())
 	return true;
 
     return false;
   }
 
+  /// Test if a given function is present in a set of functions,
+  /// by looking at the pretty representation of the function, in
+  /// addition to looking at its ID.
+  ///
+  /// This is useful because sometimes a given ELF symbol (alias)
+  /// might be for several different functions.  In that case, using
+  /// the function pretty representation might be a way to
+  /// differentiate the functions having the same ELF symbol alias.
+  ///
+  /// The function compares the ID and the qualified name of
+  /// functions.
+  ///
+  /// @param fn the function to consider.
+  ///
+  /// @parm fns the set of functions to consider.
+  ///
+  /// @return true if @p fn is present in @p fns.
+  static bool
+  fn_is_in_fns_by_repr(function_decl* fn,
+		       const std::unordered_set<function_decl*>& fns,
+		       string& pretty_representation)
+  {
+    if (!fn_is_in_fns(fn, fns))
+      return false;
+
+    const string repr = fn->get_pretty_representation();
+    const string fn_id = fn->get_id();
+    for (const auto f : fns)
+      if (f->get_id() == fn_id
+	  && f->get_pretty_representation() == repr)
+	{
+	  pretty_representation = repr;
+	  return true;
+	}
+
+    return false;
+  }
+
   ///  Test if a function is in the id-functions map.
   ///
   ///  @param fn the function to consider.
   ///
   ///  @return true iff the function is in the id-functions map.
   bool
-  fn_is_in_id_fns_map(const function_decl* fn)
+  fn_is_in_id_fns_map(function_decl* fn)
   {
-    vector<function_decl*>* fns = fn_id_is_in_id_fns_map(fn);
+    std::unordered_set<function_decl*>* fns = fn_id_is_in_id_fns_map(fn);
     if (fns && fn_is_in_fns(fn, *fns))
       return true;
     return false;
@@ -344,10 +390,10 @@  public:
 
     // First associate the function id to the function.
     string fn_id = fn->get_id();
-    vector<function_decl*>* fns = fn_id_is_in_id_fns_map(fn_id);
+    std::unordered_set<function_decl*>* fns = fn_id_is_in_id_fns_map(fn_id);
     if (!fns)
-      fns = &(id_fns_map()[fn_id] = vector<function_decl*>());
-    fns->push_back(fn);
+      fns = &(id_fns_map()[fn_id] = std::unordered_set<function_decl*>());
+    fns->insert(fn);
 
     // Now associate all aliases of the underlying symbol to the
     // function too.
@@ -361,8 +407,8 @@  public:
 	  goto loop;
 	fns = fn_id_is_in_id_fns_map(fn_id);
 	if (!fns)
-	  fns = &(id_fns_map()[fn_id] = vector<function_decl*>());
-	fns->push_back(fn);
+	  fns = &(id_fns_map()[fn_id] = std::unordered_set<function_decl*>());
+	fns->insert(fn);
       loop:
 	sym = sym->get_next_alias();
       }
@@ -403,12 +449,12 @@  public:
   ///
   /// @param fn the function to add to the set of exported functions.
   void
-  add_fn_to_exported(const function_decl* fn)
+  add_fn_to_exported(function_decl* fn)
   {
     if (!fn_is_in_id_fns_map(fn))
       {
-	fns_.push_back(const_cast<function_decl*>(fn));
-	add_fn_to_id_fns_map(const_cast<function_decl*>(fn));
+	fns_.push_back(fn);
+	add_fn_to_id_fns_map(fn);
       }
   }
 
diff --git a/src/abg-corpus.cc b/src/abg-corpus.cc
index cf6685d6..fa308151 100644
--- a/src/abg-corpus.cc
+++ b/src/abg-corpus.cc
@@ -109,6 +109,28 @@  corpus::functions&
 corpus::exported_decls_builder::exported_functions()
 {return priv_->fns_;}
 
+/// Test if a given function ID maps to several functions in the same corpus.
+///
+/// The magic of ELF symbol aliases makes it possible for an ELF
+/// symbol alias to designate several different functions.  This
+/// function tests if the ELF symbol of a given function has a aliases
+/// that designates another function or not.
+///
+/// @param fn the function to consider.
+///
+/// @return the set of functions designated by the ELF symbol of @p
+/// fn, or nullptr if the function ID maps to just @p fn.
+std::unordered_set<function_decl*>*
+corpus::exported_decls_builder::fn_id_maps_to_several_fns(function_decl* fn)
+{
+  std::unordered_set<function_decl*> *fns_for_id =
+    priv_->fn_id_is_in_id_fns_map(fn);
+  if (fns_for_id && fns_for_id->size() > 1)
+    return fns_for_id;
+
+  return nullptr;
+}
+
 /// Getter for the reference to the vector of exported variables.
 /// This vector is shared with with the @ref corpus.  It's where the
 /// set of exported variable is ultimately stored.
@@ -133,7 +155,7 @@  corpus::exported_decls_builder::exported_variables()
 ///
 /// @param fn the function to add the set of exported functions.
 void
-corpus::exported_decls_builder::maybe_add_fn_to_exported_fns(const function_decl* fn)
+corpus::exported_decls_builder::maybe_add_fn_to_exported_fns(function_decl* fn)
 {
   if (!fn->get_is_in_public_symbol_table())
     return;
@@ -1314,12 +1336,11 @@  corpus::get_functions() const
 ///
 /// @return the vector functions which ID is @p id, or nil if no
 /// function with that ID was found.
-const vector<function_decl*>*
+const std::unordered_set<function_decl*>*
 corpus::lookup_functions(const string& id) const
 {
   exported_decls_builder_sptr b = get_exported_decls_builder();
-  str_fn_ptrs_map_type::const_iterator i =
-    b->priv_->id_fns_map_.find(id);
+  auto i = b->priv_->id_fns_map_.find(id);
   if (i == b->priv_->id_fns_map_.end())
     return 0;
   return &i->second;
diff --git a/src/abg-dwarf-reader.cc b/src/abg-dwarf-reader.cc
index 037538af..66b99fd5 100644
--- a/src/abg-dwarf-reader.cc
+++ b/src/abg-dwarf-reader.cc
@@ -4460,19 +4460,14 @@  public:
 
     string id = fn->get_id_string();
 
-    const vector<function_decl*> *fns = corp->lookup_functions(id);
+    const std::unordered_set<function_decl*> *fns = corp->lookup_functions(id);
     if (!fns)
       return false;
 
-    for (vector<function_decl*>::const_iterator i = fns->begin();
-	 i != fns->end();
-	 ++i)
-      {
-	function_decl* f = *i;
-	ABG_ASSERT(f);
-	if (f->get_symbol())
-	  return true;
-      }
+    for (auto f : *fns)
+      if (f->get_symbol())
+	return true;
+
     return false;
   }
 
diff --git a/src/abg-fe-iface.cc b/src/abg-fe-iface.cc
index f3798cd6..bc272425 100644
--- a/src/abg-fe-iface.cc
+++ b/src/abg-fe-iface.cc
@@ -310,7 +310,7 @@  fe_iface::maybe_add_fn_to_exported_decls(const function_decl* fn)
   if (fn)
     if (corpus::exported_decls_builder* b =
 	corpus()->get_exported_decls_builder().get())
-      b->maybe_add_fn_to_exported_fns(fn);
+      b->maybe_add_fn_to_exported_fns(const_cast<function_decl*>(fn));
 }
 
 /// Try and add the representation of the ABI of a variable to the set
diff --git a/src/abg-ir.cc b/src/abg-ir.cc
index 047b755d..514013c7 100644
--- a/src/abg-ir.cc
+++ b/src/abg-ir.cc
@@ -8900,6 +8900,30 @@  get_function_type_name(const function_type& fn_type,
   return env.intern(o.str());
 }
 
+/// Get the ID of a function, or, if the ID can designate several
+/// different functions, get its pretty representation.
+///
+/// @param fn the function to consider
+///
+/// @return the function ID of pretty representation of @p fn.
+interned_string
+get_function_id_or_pretty_representation(function_decl *fn)
+{
+  ABG_ASSERT(fn);
+
+  interned_string result = fn->get_environment().intern(fn->get_id());
+
+  if (corpus *c = fn->get_corpus())
+    {
+      corpus::exported_decls_builder_sptr b =
+	c->get_exported_decls_builder();
+      if (b->fn_id_maps_to_several_fns(fn))
+	result = fn->get_environment().intern(fn->get_pretty_representation());
+    }
+
+  return result;
+}
+
 /// Get the name of a given method type and return a copy of it.
 ///
 /// @param fn_type the function type to consider.