# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1484867385 -3600
# Node ID e678f1913dabede0fa8949a5e0acd22a470c91a1
# Parent  c0237ee9fb81de5cd75a5c4bf2aa68db8e5cedb5
Record namespaces with exception handling in order to avoid generating unused
variables that provoke warnings when compiling the generated program.

diff -r c0237ee9fb81 -r e678f1913dab inspector.py
--- a/inspector.py	Fri Jan 20 00:08:26 2017 +0100
+++ b/inspector.py	Fri Jan 20 00:09:45 2017 +0100
@@ -4,7 +4,7 @@
 Inspect and obtain module structure.
 
 Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013,
-              2014, 2015, 2016 Paul Boddie <paul@boddie.org.uk>
+              2014, 2015, 2016, 2017 Paul Boddie <paul@boddie.org.uk>
 
 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
@@ -920,6 +920,8 @@
         Process the given "try...except" node 'n'.
         """
 
+        self.record_exception_handler()
+
         tracker = self.trackers[-1]
         tracker.new_branchpoint()
 
@@ -967,6 +969,8 @@
         Process the given "try...finally" node 'n'.
         """
 
+        self.record_exception_handler()
+
         tracker = self.trackers[-1]
         self.process_structure_node(n.body)
 
@@ -1492,4 +1496,12 @@
         self.function_targets[path][0] -= 1
         self.function_arguments[path][0] -= len(args) + 1
 
+    # Exceptions.
+
+    def record_exception_handler(self):
+
+        "Record the current namespace as employing an exception handler."
+
+        self.exception_namespaces.add(self.get_namespace_path())
+
 # vim: tabstop=4 expandtab shiftwidth=4
diff -r c0237ee9fb81 -r e678f1913dab modules.py
--- a/modules.py	Fri Jan 20 00:08:26 2017 +0100
+++ b/modules.py	Fri Jan 20 00:09:45 2017 +0100
@@ -4,7 +4,7 @@
 Module abstractions.
 
 Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013,
-              2014, 2015, 2016 Paul Boddie <paul@boddie.org.uk>
+              2014, 2015, 2016, 2017 Paul Boddie <paul@boddie.org.uk>
 
 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
@@ -71,6 +71,10 @@
         self.function_targets = {}
         self.function_arguments = {}
 
+        # Exception handler details.
+
+        self.exception_namespaces = set()
+
         # Attribute usage at module and function levels.
 
         self.attr_usage = {}
@@ -401,6 +405,7 @@
             self._get_attr_access_modifiers(f)
             self._get_constant_literals(f)
             self._get_constant_values(f)
+            self._get_exception_namespaces(f)
 
         finally:
             f.close()
@@ -633,6 +638,12 @@
             self.constant_values[name] = value, value_type, encoding
             line = f.readline().rstrip()
 
+    def _get_exception_namespaces(self, f):
+        f.readline() # "exception namespaces:"
+        values = f.readline.rstrip().split(", ")
+        self.exception_namespaces = set(values)
+        f.readline()
+
     # Generic parsing methods.
 
     def from_lines(self, f, d):
@@ -759,10 +770,15 @@
         (empty line)
         "attribute access modifiers:"
         zero or more: qualified function name " " local/global variable name " " attribute name " " access modifiers
+        (empty line)
         "constant literals:"
         zero or more: qualified scope name " " value type " " constant literal
+        (empty line)
         "constant values:"
         zero or more: qualified name " " value type " " constant literal
+        (empty line)
+        "exception namespaces:"
+        qualified names
 
         All collections of names are separated by ", " characters.
 
@@ -995,6 +1011,12 @@
                 value, value_type, encoding = self.constant_values[name]
                 print >>f, name, value_type, encoding or "{}", repr(value)
 
+            print >>f
+            print >>f, "exception namespaces:"
+            paths = list(self.exception_namespaces)
+            paths.sort()
+            print >>f, ", ".join(paths)
+
         finally:
             f.close()
 
diff -r c0237ee9fb81 -r e678f1913dab translator.py
--- a/translator.py	Fri Jan 20 00:08:26 2017 +0100
+++ b/translator.py	Fri Jan 20 00:09:45 2017 +0100
@@ -1722,7 +1722,10 @@
 
         self.writeline("__ref __tmp_context, __tmp_value, __tmp_target_value;")
         self.writeline("__attr %s__tmp_result;" % targets)
-        self.writeline("__exc __tmp_exc;")
+
+        module = self.importer.get_module(self.name)
+        if self.get_namespace_path() in module.exception_namespaces:
+            self.writeline("__exc __tmp_exc;")
 
     def write_parameters(self, name):