Compile time error if name is used before variable is declared

Compile time error if name is used before variable is declared

Implement proper semantics if a name has been referenced in a
block and later a variable with that same name is declared.

Fix library code that was wrong.

Add new language test, delete a couple of tests that are
outdated, file co19 bug 649.

Dart2js and dart2dart are not yet implementing these compile-time
errors.

R=iposva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=29770

[Ivan Posva, 2013-11-01 16:35:12]

LGTM -ip

https://codereview.chromium.org/51533003/diff/1/runtime/vm/parser.cc
File runtime/vm/parser.cc (right):

https://codereview.chromium.org/51533003/diff/1/runtime/vm/parser.cc#newcode5273
runtime/vm/parser.cc:5273: script_.GetTokenLocation(previous_pos, &line_number,
NULL);
Since we are only getting the line number here we should not need to make the
distinction whether we have source or not.

https://codereview.chromium.org/51533003/diff/1/runtime/vm/scopes.cc
File runtime/vm/scopes.cc (right):

https://codereview.chromium.org/51533003/diff/1/runtime/vm/scopes.cc#newcode104
runtime/vm/scopes.cc:104: ref->set_token_pos(token_pos);
Is it your intent to show the last reference when printing the possible error?

[hausner, 2013-11-01 16:42:51]

Thank you.

Nicolas, I removed tests/language/bailout3_test.dart because my impression is
that it depends on declaring variable a in line 31 after the name a has been
used in the same scope. This is not legal in dart, and the test no longer
compiles after this change. Is my assumption correct? If not, let me know how to
fix the test please.

https://codereview.chromium.org/51533003/diff/1/runtime/vm/parser.cc
File runtime/vm/parser.cc (right):

https://codereview.chromium.org/51533003/diff/1/runtime/vm/parser.cc#newcode5273
runtime/vm/parser.cc:5273: script_.GetTokenLocation(previous_pos, &line_number,
NULL);
On 2013/11/01 16:35:12, Ivan Posva wrote:
> Since we are only getting the line number here we should not need to make the
> distinction whether we have source or not.

True. I figured line numbers make less sense if a user has no access to the
source code. Removed the distinction.

https://codereview.chromium.org/51533003/diff/1/runtime/vm/scopes.cc
File runtime/vm/scopes.cc (right):

https://codereview.chromium.org/51533003/diff/1/runtime/vm/scopes.cc#newcode104
runtime/vm/scopes.cc:104: ref->set_token_pos(token_pos);
On 2013/11/01 16:35:12, Ivan Posva wrote:
> Is it your intent to show the last reference when printing the possible error?
Yes.

[hausner, 2013-11-01 21:28:43]

Committed patchset #1 manually as r29770 (presubmit successful).

[ngeoffray, 2013-11-01 21:41:06]

https://codereview.chromium.org/51533003/diff/1/tests/language/bailout3_test....
File tests/language/bailout3_test.dart (left):

https://codereview.chromium.org/51533003/diff/1/tests/language/bailout3_test....
tests/language/bailout3_test.dart:31: var a = bar();
This should be var b = bar().

https://codereview.chromium.org/51533003/diff/1/tests/language/bailout3_test....
tests/language/bailout3_test.dart:34: Expect.equals(1, a.length);
-> b.length.