Tighten up attribute recognition during parsing

Now it should be possible to use `[]` for wildcard patterns, for example:

  foo = foo.[hit]xx

Note that a leading bracket expression will still be recognized as attributes
and escaping or quoting it will inhibit pattern matching. To resolve this case
we need to specify an empty attribute list:

  foo = [] [abc]-foo.cxx

2 files changed, 3 insertions, 4 deletions

diff --git a/old-tests/attribute/buildfile b/old-tests/attribute/buildfile
index 7338641..a9abf24 100644
--- a/old-tests/attribute/buildfile
+++ b/old-tests/attribute/buildfile
@@ -6,10 +6,10 @@
 #[foo=dir/file{bar}]  # error: invalid attribute key
 
 #[foo] print hello    # error: attributes before print
-#[foo]./              # error: attributes before directory scope
+#[foo] ./             # error: attributes before directory scope
 #{
 #}
-#[foo]./:             # error: attributes before target scope
+#[foo] ./:            # error: attributes before target scope
 #./: [foo] buildfile  # error: attributes before prerequisites
 #import [foo] libz    # error: attributes without variable
 
diff --git a/old-tests/variable/override/test.sh b/old-tests/variable/override/test.sh
index 94ed61f..4675b7e 100755
--- a/old-tests/variable/override/test.sh
+++ b/old-tests/variable/override/test.sh
@@ -53,8 +53,7 @@ function test ()
   fi
 }
 
-fail foo=bar[]             # error: unexpected [ in variable assignment 'foo=bar[]'
-fail foo=[string]bar       # error: typed override of variable foo
+fail "foo= [string] bar"    # error: typed override of variable foo
 #fail "!foo=bar" "!foo=BAR" # error: multiple global overrides of variable foo
 #fail "foo=bar" "foo=BAR"   # error: multiple project overrides of variable foo
 #fail "%foo=bar" "%foo=BAR" # error: multiple project overrides of variable foo