[lmi-commits] [lmi] master 78a4de0 5/7: Enable '-Wnull-dereference'; fix the issues it flags

[Greg Chicares]

branch: master
commit 78a4de074070eae5daf69dfd397297765d8a3793
Author: Gregory W. Chicares <address@hidden>
Commit: Gregory W. Chicares <address@hidden>

    Enable '-Wnull-dereference'; fix the issues it flags
    
    Incidentally, shortened an argument name to make the widest line
    (aside from the copyright notice) no wider than eighty characters.
---
 input_sequence_entry.cpp |  2 +-
 main_wx_test.cpp         |  6 +++++-
 system_command_wx.cpp    | 17 +++++++++--------
 workhorse.make           |  8 +++++---
 4 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/input_sequence_entry.cpp b/input_sequence_entry.cpp
index 902ef9b..34d1ce9 100644
--- a/input_sequence_entry.cpp
+++ b/input_sequence_entry.cpp
@@ -806,7 +806,7 @@ void InputSequenceEditor::remove_row(int row)
         int index = row * Col_Max;
         wxWindow* win = sizer_->GetItem(index)->GetWindow();
         sizer_->Detach(index);
-        win->Destroy();
+        win && win->Destroy();
         }
 
     redo_layout();
diff --git a/main_wx_test.cpp b/main_wx_test.cpp
index a4d5a3d..25ee2a3 100644
--- a/main_wx_test.cpp
+++ b/main_wx_test.cpp
@@ -591,7 +591,11 @@ wxWindow* wx_test_focus_controller_child(MvcController& 
dialog, char const* name
     // until we reach it.
     for(wxWindow* maybe_page = w;;)
         {
-        wxWindow* const maybe_book = maybe_page->GetParent();
+        wxWindow* const maybe_book =
+            (maybe_page && maybe_page->GetParent())
+            ? maybe_page->GetParent()
+            : nullptr
+            ;
 
         // As we know that w is a descendant of the dialog, this check ensures
         // that the loop terminates as sooner or later we must reach the dialog
diff --git a/system_command_wx.cpp b/system_command_wx.cpp
index b7d9f85..7a28236 100644
--- a/system_command_wx.cpp
+++ b/system_command_wx.cpp
@@ -77,22 +77,23 @@ void assemble_console_lines
 /// for the wxEXEC_NODISABLE rationale. This is potentially dangerous,
 /// and could be inhibited (by an extra argument) if ever needed.
 
-void concrete_system_command(std::string const& command_line)
+void concrete_system_command(std::string const& cmd_line)
 {
     Timer timer;
     wxBusyCursor reverie;
 
-    bool const b =
-                                  wxTheApp
-        && dynamic_cast<wxFrame*>(wxTheApp->GetTopWindow())
-        && dynamic_cast<wxFrame*>(wxTheApp->GetTopWindow())->GetStatusBar()
+    wxFrame const* f =
+                                 wxTheApp
+        ? dynamic_cast<wxFrame*>(wxTheApp->GetTopWindow())
+        : nullptr;
         ;
+    bool const b = f && f->GetStatusBar();
     std::ostream& statusbar_if_available = b ? status() : null_stream();
 
     statusbar_if_available << "Running..." << std::flush;
     wxArrayString output;
     wxArrayString errors;
-    long int exit_code = wxExecute(command_line, output, errors, 
wxEXEC_NODISABLE);
+    long int exit_code = wxExecute(cmd_line, output, errors, wxEXEC_NODISABLE);
     statusbar_if_available << timer.stop().elapsed_msec_str() << std::flush;
 
     if(0L == exit_code)
@@ -103,7 +104,7 @@ void concrete_system_command(std::string const& 
command_line)
         {
         alarum()
             << "Command '"
-            << command_line
+            << cmd_line
             << "' not recognized."
             << std::flush
             ;
@@ -114,7 +115,7 @@ void concrete_system_command(std::string const& 
command_line)
             << "Exit code "
             << exit_code
             << " from command '"
-            << command_line
+            << cmd_line
             << "'.\n"
             ;
         assemble_console_lines(alarum(), output, "Output:");
diff --git a/workhorse.make b/workhorse.make
index 382d8fd..1d4db80 100644
--- a/workhorse.make
+++ b/workhorse.make
@@ -447,6 +447,7 @@ gcc_common_warnings := \
   -Wlogical-op \
   -Wmissing-include-dirs \
   -Wmultichar \
+  -Wnull-dereference \
   -Wpacked \
   -Wpointer-arith \
   -Wredundant-decls \
@@ -471,7 +472,6 @@ gcc_common_warnings := \
 
 postponed_gcc_common_warnings := \
   -Wmissing-declarations \
-  -Wnull-dereference \
   -Wswitch-enum \
 
 gcc_c_warnings := \
@@ -615,10 +615,13 @@ endif
 # Too many warnings for wx and various boost libraries:
 #  -Wold-style-cast \
 
+# See:
+#   https://lists.nongnu.org/archive/html/lmi/2019-03/msg00018.html
+$(xmlwrapp_objects): gcc_common_extra_warnings += -Wno-null-dereference
+
 # SOMEDAY !! Address some of these '-Wconversion' issues.
 
 wno_conv_objects := \
-  $(xmlwrapp_objects) \
   CgiUtils.o \
   currency_test.o \
   rate_table.o \
@@ -632,7 +635,6 @@ wno_sign_conv_objects := \
   $(boost_filesystem_objects) \
   $(boost_regex_objects) \
   $(wx_dependent_objects) \
-  $(xmlwrapp_objects) \
   CgiEnvironment.o \
   CgiUtils.o \
   crc32.o \