[mycpp] Write else: body connected with if 0:

This is useful for comparing Pythona and C++.

Note that mycpp can't print if 0:, because it happens at the top level
too (outside of functions).

Found a translation bug with arg_jw.pretty in 'json write'.

builtin/json_ysh.py

@@ -15,6 +15,7 @@
 from frontend import args
 from frontend import typed_args
 from mycpp import mylib
+from mycpp.mylib import log
 from ysh import cpython
 
 import sys
@@ -25,6 +26,8 @@
 if TYPE_CHECKING:
     from core.ui import ErrorFormatter
 
+_ = log
+
 _JSON_ACTION_ERROR = "builtin expects 'read' or 'write'"
 
 
@@ -72,14 +75,17 @@ def Run(self, cmd_val):
             val = rd.PosValue()
             rd.Done()
 
-            if arg_jw.pretty:
+            if arg_jw.pretty:  # C++ BUG Here!
                 indent = arg_jw.indent
+                #log('arg_jw indent %d', indent)
                 extra_newline = False
             else:
                 # How yajl works: if indent is -1, then everything is on one line.
                 indent = -1
                 extra_newline = True
 
+            #log('json write indent %d', indent)
+
             if mylib.PYTHON:
                 #if 0:
                 obj = cpython._ValueToPyObj(val)
@@ -90,7 +96,7 @@ def Run(self, cmd_val):
                     sys.stdout.write('\n')
             else:
                 buf = mylib.BufWriter()
-                self.printer.Print(val, buf, indent=indent)
+                self.printer.Print(val, buf, indent)
                 self.stdout_.write(buf.getvalue())
                 self.stdout_.write('\n')
 

mycpp/const_pass.py

@@ -474,8 +474,8 @@ def visit_if_stmt(self, o: 'mypy.nodes.IfStmt') -> T:
             return
 
         # Omit if 0:
-        if isinstance(cond, IntExpr) and cond.value == 0:
-            return
+        #if isinstance(cond, IntExpr) and cond.value == 0:
+        #    return
 
         # Omit if TYPE_CHECKING blocks.  They contain type expressions that
         # don't type check!

mycpp/cppgen_pass.py

@@ -2738,6 +2738,10 @@ def visit_if_stmt(self, o: 'mypy.nodes.IfStmt') -> T:
 
         # Omit if 0:
         if isinstance(cond, IntExpr) and cond.value == 0:
+            # But write else: body
+            # Note: this would be invalid at the top level!
+            if o.else_body:
+                self.accept(o.else_body)
             return
 
         # Omit if TYPE_CHECKING blocks.  They contain type expressions that