Printing a useful error message if a version field is a num

sdk/lib/_internal/pub/lib/src/pubspec.dart

Index: sdk/lib/_internal/pub/lib/src/pubspec.dart
diff --git a/sdk/lib/_internal/pub/lib/src/pubspec.dart b/sdk/lib/_internal/pub/lib/src/pubspec.dart
index 55b2df7ba57935ac2744e369b76012169e6515e1..75cfd8c76f9e3fcb700d36ce59a2caf8f237757f 100644
--- a/sdk/lib/_internal/pub/lib/src/pubspec.dart
+++ b/sdk/lib/_internal/pub/lib/src/pubspec.dart
@@ -74,6 +74,9 @@ class Pubspec {
     }
 
     var span = fields.nodes['version'].span;
+    if (version is num) {
+      _error('"version" field must be written in MAJOR.MINOR.PATCH[SUFFIX] format', span);

[Bob Nystrom, 2014/10/06 16:19:34]

I think the all caps part might confuse users a bit. How about:

"version" field must have three numeric components: major, minor, and patch.
Instead of "$version", consider "$fixed".

where fixed is the original version with ".0.0" added if it's an int or ".0"
added if it is a float.

Also, long line.

[srawlins, 2014/10/06 17:33:08]

Love it! Done.

+    }
     if (version is! String) {
       _error('"version" field must be a string.', span);
     }