It has been reported in sbt/sbt#1237 that stack overflows may occur during the
extraction of used names (and later of dependencies between files). This
problem has been introduced by sbt/sbt#1163, which was about recording the
dependencies of macro arguments.
When a macro is expanded, the compiler attaches the tree before expansion to
the tree representing the expanded macro. As of Scala 2.11-RC3, some macros
have themselves attached as original tree, which caused the same macro to be
inspected over and over until a stack overflow.
This commit solves this problem by making sure that the original of a macro
expansion will be inspected if and only if it is different from the expanded
tree.
Fixessbt/sbt#1237
Add two scripted tests that illustrate a problem occurring with Scala 2.11-RC3
where some macros have themselves attached as original tree, which causes a
stack overflow during dependency extraction.
* sbt 0.12.3 introduced sbt/sbt@482f99 to fix#637 and #641.
* The underlying issue of #641 was an incorrect classifier, and it was
fixed in sbt/sbt@718fa9 for #683 and shipped as sbt 0.13.0.
Prior to this commit, a class that inherited a macro from another
class was considered by incremental compiler as having a macro.
Now, only classes that explicitly define a macro are considered as having
a macro. This influences decision whether to invalidate (recompile)
dependencies of a file that inherits a macro upon a whitespace change.
From now on, we don't invalidate dependencies in such case which
results in much better incremental compiler experience when macros are
being involved. Check #1142 for detailed discussion.
The change to the behavior is reflected by marking the
source-dependencies/inherited-macros test as passing.
The source-dependencies/macro test covers the case of defining the macro
directly in source file. Therefore we know that the desired behavior of
invalidating dependencies of macros is preserved.
Fixes#1142
Add a scripted test documents the current behavior of incremental
compiler when it comes to handling of inherited macros. A whitespace
change to a file that inherits a macro triggers recompilation of all files that
depend (by composition or inheritance) on that file.
* AutoImport trait is subsumed by def autoImport method under
AutoPlugin class.
* When def autoImport is overridden by a lazy val or a val, *.sbt
automatically imports autoImport._.
Add test analogous to source-dependencies/macro-arg-dep
but check if dependencies of nested macro applications are handled
properly. Nested macro applications are tricky because we have to look
into original (before macro expansion) trees recursively. This test verifies
that.
Add a unit test which checks whether we capture dependencies introduced
by arguments to macros. Those dependencies are special because macros
get expanded during type checking and arguments to macros are not visible
during regular tree walk.
It was not possible to make `ScalaCompilerForUnitTesting` compile several
files in different runs, which means that it was not possible to compile
and use a macro in a test case, since macros cannot be used in the same
compilation run that defines them.
This commit allows a test case to provide multiple grouped snippets of
code that will be compiled in separate runs.
For instance :
List(Map(<snippet A>, <snippet B>), Map(<snippet C>))
Here, <snippet A> and <snippet B> will be compiled together, and then
<snippet C> will be compiled, and will be able to use symbols defined
in <snippet A> or <snippet B>.
Macros take arguments as trees and return some other trees; both of
them have dependencies but we see trees only after expansion and
recorded only those dependencies.
This commit solves this problem by looking into the attachments of the
trees that are supposed to contain originals of macro expansions and
recording dependencies of the macro before its expansion.
This allows plugins to define a Plugins instance that captures both the
plugin and its required dependencies.
Also fixed up some scaladocs that were wrong.
Martin Duhem
Josh Suereth
Eugene Yokota
Dan Sanduleac
Grzegorz Kossakowski
Ismael Juma
Sergey Andreev
James Roper