Check for and disallow rules the process the output of other rules

pylib/gyp/input.py

Index: pylib/gyp/input.py
diff --git a/pylib/gyp/input.py b/pylib/gyp/input.py
index 568049df6c349c6dae60fcbd966e73a0c628a7ee..6bd4d172baae21cc153689401a390f10d6207c65 100644
--- a/pylib/gyp/input.py
+++ b/pylib/gyp/input.py
@@ -2190,6 +2190,15 @@ def ValidateRulesInTarget(target, target_dict, extra_sources_for_rules):
   rule_extensions = {}
 
   rules = target_dict.get('rules', [])
+
+  # Gather the outputs for all rules with process_outputs_as_sources so we can
+  # validate that they're not chained below.
+  processed_outputs = []
+  for rule in rules:
+    if rule.get('process_outputs_as_sources', False):
+      for output in rule['outputs']:
+        processed_outputs.append((rule, output))

[Evan Martin, 2012/05/18 22:53:36]

Why not a map of output extension => other stuff, so the below bit of code is a
single lookup?

+
   for rule in rules:
     # Make sure that there's no conflict among rule names and extensions.
     rule_name = rule['rule_name']
@@ -2207,6 +2216,17 @@ def ValidateRulesInTarget(target, target_dict, extra_sources_for_rules):
                        rule_name)
     rule_extensions[rule_extension] = rule
 
+    # Make sure rules aren't chained (i.e. the output of one rule with
+    # process_outputs_as_sources is the input for another rule). Some
+    # generators can't reasonably support this.
+    for other, output in processed_outputs:
+      if other == rule:
+        continue
+      if output.endswith('.' + rule_extension):
+        raise KeyError, ('target %s contains "%s" rule that would handle '
+                         'the output of other rule %s (processing %s)' %
+                         (target, rule_extension, other['rule_name'], output))
+
     # Make sure rule_sources isn't already there.  It's going to be
     # created below if needed.
     if 'rule_sources' in rule: