Previously:
Without `--screw-ie`, UglifyJS would always leak names of function
expressions into the containing scope, as if they were function
declarations. That was to emulate IE<9 behavior. Code relying on this
IE bug would continue to work properly after mangling, although it would
only work in IE (since other engines don't share the bug). Sometimes
this broke legitimage code (see #153 and #155).
With `--screw-ie` the names would not be leaked into the current scope,
working properly in legit cases; but still it broke legit code when
running in IE<9 (see #24).
Currently:
Regardless of the `--screw-ie` setting, the names will not be leaked.
Code relying on the IE bug will not work properly after mangling.
<evil laughter here>
Without `--screw-ie`: a hack has been added to the mangler to avoid
using the same name for a function expression and some other variable in
the same scope. This keeps legit code working, at the (negligible,
indeed) cost of one more identifier.
With `--screw-ie` you allow the mangler to name function expressions
with the same identifier as another variable in scope. After mangling
code might break in IE<9.
Oh man, the commit message is longer than the patch.
Fix#153, #155
For now the implication is that UglifyJS will not leak a function
expression's name in the surrounding scope (IE < 9 does that).
(ref. mishoo/UglifyJS#485)
AST_Accessor will represent the function for a setter or getter. Since they
are not mangleable, and they should not introduce a name in scope, we have a
new node for their name (AST_SymbolAccessor) which doesn't inherit from
AST_SymbolDeclaration.
fix#37
we need to mangle names from outermost to innermost scope; mangling names
from inner scopes before we got to the outer scope won't work correctly,
therefore sorting doesn't make sense.
- all symbols now have a `thedef` property which is a SymbolDef object,
instead of the `uniq` that we had before (pointing to the first occurrence
of the name as declaration).
- for undeclared symbols we still create a SymbolDef object in the toplevel
scope but mark it "undeclared"
- we can now call figure_out_scope after squeezing, which is useful in order
not to mangle names that were dropped by the squeezer
The following nodes were instances of AST_BlockStatement: AST_Scope,
AST_SwitchBlock, AST_SwitchBranch. Also, AST_Try, AST_Catch, AST_Finally
were having a body instanceof AST_BlockStatement.
Overloading the meaning of AST_BlockStatement this way turned out to be a
mess; we now have an AST_Block class that is the base class for things
having a block of statements (might or might not be bracketed). The
`this.body` of AST_Scope, AST_Try, AST_Catch, AST_Finally is now an array of
statements (as they inherit from AST_Block).
Avoiding calling superclass's _walk function in walkers (turns out we walked
a node multiple times).
