qapi: Prepare for catching more semantic parse errors

This patch widens the scope of a try block (with the attending
reindentation required by Python) in preparation for a future
patch adding more instances of QAPIExprError inside the block.
It's easier to separate indentation from semantic changes, so
this patch has no real behavior change.

Backports commit 268a1c5eb10832c2e4476d3fe199ea547dabecb7 from qemu

qemu/scripts/qapi.py

@@ -398,6 +398,7 @@ def check_exprs(schema):
             check_event(expr, info)
 
 def parse_schema(input_file):
+    # First pass: read entire file into memory
     try:
         schema = QAPISchema(open(input_file, "r"))
     except (QAPISchemaError, QAPIExprError), e:
@@ -406,24 +407,26 @@ def parse_schema(input_file):
 
     exprs = []
 
-    for expr_elem in schema.exprs:
-        expr = expr_elem['expr']
-        if expr.has_key('enum'):
-            add_enum(expr['enum'], expr.get('data'))
-        elif expr.has_key('union'):
-            add_union(expr)
-        elif expr.has_key('type'):
-            add_struct(expr)
-        exprs.append(expr)
-
-    # Try again for hidden UnionKind enum
-    for expr_elem in schema.exprs:
-        expr = expr_elem['expr']
-        if expr.has_key('union'):
-            if not discriminator_find_enum_define(expr):
-                add_enum('%sKind' % expr['union'])
-
     try:
+        # Next pass: learn the types.
+        for expr_elem in schema.exprs:
+            expr = expr_elem['expr']
+            if expr.has_key('enum'):
+                add_enum(expr['enum'], expr.get('data'))
+            elif expr.has_key('union'):
+                add_union(expr)
+            elif expr.has_key('type'):
+                add_struct(expr)
+            exprs.append(expr)
+
+        # Try again for hidden UnionKind enum
+        for expr_elem in schema.exprs:
+            expr = expr_elem['expr']
+            if expr.has_key('union'):
+                if not discriminator_find_enum_define(expr):
+                    add_enum('%sKind' % expr['union'])
+
+        # Final pass - validate that exprs make sense
         check_exprs(schema)
     except QAPIExprError, e:
         print >>sys.stderr, e