Specifically, we're turning off Eclipse warnings about missing version
constraints on required bundles ("Require-Bundle"), exported
packages ("Export-Package"), and imported packages ("Import-Package").
We're not turning these off absolutely everywhere, though: only in
packages where one or more such warnings were actually being reported.
So if a given package was already providing all version constraints
for, say, package imports, then we've kept that warning on in that
package.
Honestly I don't entirely understand the practical implications of
these warnings. However, there were 355 of them across many WALA
subprojects. I take this as evidence that the WALA developers do not
consider these version constraints to be important. Therefore, we may
as well stop warning about something we have no intention of fixing.
That being said, if we *do* want to fix some or all of these, I
welcome any advice on what those fixes should look like. I am rather
ignorant about all things OSGi.
Manu requested that we use this approach instead of adding
`@SuppressWarnings("unused")` at each affected catch block. That
seems reasonable to me, given the large number of such warnings and
the lack of likely harm from ignoring such caught exceptions.
Fixing these Javadoc comments would require adding packages to various
other packages' build paths. In some of the cases suppressed,
changing build paths in that manner would create circular build
dependencies. In other cases, it would simply add a Javadoc-motivated
dependency that does not exist for the real code, which seems
undesirable. For a few cases, the reference seems to be to types in
code we don't even have here, such as code from "android" or
"org.mozilla" packages.
These changes turn off Eclipse warnings for Javadoc tags without
descriptions. In some subprojects, we turn these off entirely. In
others, leave on missing-descrption checks for "@return" tags only.
We don't turn this warning off in all projects. Rather, we turn it
off only in projects that were producing at least one such warning.
In other words, if a project was already completely "clean" with
respect to this warning, then we leave this warning enabled for that
project.
Turning off these warnings is a partial declaration of Javadoc
bankruptcy. In an ideal world, we would enable and fix all of these
warnings. However, there are 576 of them. Apparently the WALA team's
implicit coding style says that omitting descriptions is OK. If
there's no intent to systematically add descriptions, then we may as
well turn off these warnings so that we can see other warnings that we
may want to fix.
Effectively these two checks could only be false if the instance being
tested were null. So we replace the instanceof checks with null
checks. Sometimes that, in turn, makes other surrounding code
simpler. In the case of ApplicationLoaderFilter.test, for example,
a whole conditional case ("o instanceof LocalPointerKey") becomes
statically impossible. That seems a bit strange to me, but that's
what the code was effectively doing.
In the cases addressed here, the caught exception was being "handled"
by throwing some new exception. Instead of discarding the old
exception, pass it to the new exception's constructor to indicate the
original cause of the newly-created exception. This practice, called
"exception chaining", can often be useful in debugging.
This fixes the remaining 34 Eclipse "Resource '...' should be managed
by try-with-resource" warnings that were still left after the previous
commit.
Unlike the fixes in that previous commit, the changes here are *not*
plugging potential resource leaks. However, in many cases that is
simply because the code before the close() call cannot currently throw
exceptions. If exceptions became possible in the future, leaks could
result. Using try-with-resource preemptively avoids that.
Furthermore, in code that was already dealing with exceptions, the
try-with-resource style is usually considerably simpler.
This fixes 33 out of 37 Eclipse "Potential resource leak: '...' may
not be closed" warnings. It also fixes 3 out of 37 Eclipse "Resource
'...' should be managed by try-with-resource" warnings, although that
was not the main focus of this effort.
The remaining 4 warnings about potential resource leaks all involve a
leaked JarFile instance that is passed to a JarFileModule constructor
call. JarFileModile never attempts to close its underlying JarFile;
this code is written as though JarFile cleanup were the caller's
responsibility. However, the JarFile often cannot be closed by the
code that creates the JarFileModule either, since the JarFile needs to
remain open while the JarFileModule is in use, and some of these
JarFileModules stay around beyond the lifetime of the code that
created them. Truly fixing this would essentially require making
JarFileModule implement Closeable, which in turn would probably
require that Module implement Closeable, which in turn would require
changes to lots of code that deals with Module instances to arrange
for them to be properly closed. That's more invasive than I'm
prepared to take on right now.
Instead, rely on Java's ability to infer type parameters in many
contexts. This removes 665 Eclipse warnings.
Note: a few of these changes are to files under "test" subdirectories.
Presumably those are files that serve as test inputs rather than being
part of WALA code proper. As far as I can tell, these changes do not
break any WALA tests. But if any of those tests were specifically
intended to exercise WALA on code with non-inferred generic type
parameters, then I really should be leaving those alone.
Previously, the various Eclipse projects' Java configurations used
mixtures of 1.6, 1.7, and 1.8. Many were internally inconsistent,
such as requiring 1.7 in "MANIFEST.MF" but 1.6 in the Eclipse JDT
build preferences. The Travis-CI configuration tests against both 1.7
and 1.8, but does not test against 1.6.
Across all projects, the most common version was 1.7. So I'm going to
assume that 1.7 is the intended build target. This commit makes 1.7
the selected version nearly everywhere.
"com.ibm.wala.core.testdata" is the one exception. This specific
project uses a few features only found in 1.8, such as lambda
expressions. Previously, "com.ibm.wala.core.testdata" used 1.7 in
some aspects of its configuration but 1.8 in others. Now it
consistently targets 1.8. I wish this one project didn't need to be
inconsistent with the rest of WALA, but at least now it's consistent
with itself.
(Personally, I'd be happy to target 1.8 only. But my impression
across all of these configuration files is that the WALA developers
still want to be compatible with 1.7. If that is no longer a
requirement, let me know and I will adjust these changes accordingly
to target 1.8 only.)
This change eliminates 11 "There is no 'jre.compilation.profile' build
entry and the project has Java compliance preferences set" warnings
and 13 "The JRE container on the classpath is not a perfect match to
the 'JavaSE-1.7' execution environment" warnings. However, it also
adds 450 "Redundant specification of type arguments <...>" warnings
and 17 "Resource '...' should be managed by try-with-resource"
warnings. So this seems like a net step backward in my wish to reduce
WALA warnings. However, those new warnings concern Java 1.7 language
features that we were not previously using to good effect in projects
that targeted 1.6. If we all agree that we can now target 1.7
instead, then we can use these helpful features as the newly-added
warnings suggest. So I call that a step in the right direction.
I think the "target/p2artifacts.xml" and "target/p2content.xml" files
are generated by Maven. They are well-formed XML but Eclipse's XML
validator legitimately warns that they lack grammar constraints.
Since we're not maintaining the tool that creates these files, we are
not in a position to do anything about that. Therefore, we may as
well exclude these from validation entirely. That way we can
more-clearly recognize warnings that we *can* do something about.
Most of the invalid HTML arose from bare "<" and ">" characters.
These should be escaped as "<" and ">" when not intended to
introduce HTML tags. When you have many such characters close
together, "{@literal ...}" is a nice, readable alternative that
automatically escapes its contents. If the text in question is
intended to be a code fragment, then "{@code ...}" is appropriate:
this is essentially equivalent to "<code>{@literal ...}</code>".
There were a few other HTML violations too, but none common enough to
be worth detailing here.
Eclipse validation warns about invalid HTML content in all
Maven-generated "target/site/dependency-convergence.html" files. The
warnings are legitimate: these HTML files are indeed invalid.
However, we don't maintain the tool that generates these files, so we
are not in a position to fix them. Better, therefore, to suppress
these warnings so that we can notice and fix other problems over which
we do have control.
In general, the WALA code base is not really ready for nullness
checking. It would be nice if we got there some day, but I'm not
planning to take that on now or any time soon. Until then, it's not
useful to warn about missing @NonNullByDefault declarations on WALA
packages.
See also older commit 7b6811b.
Eclipse Mars Service Release 2 finds 45 potential null pointer accesses
across WALA's various Eclipse projects. Eclipse ignores these by
default, but any individual user may have changed their personal Eclipse
configuration to treat them as warnings or errors. Thus, some people
will find that the code builds while others find that it fails. Better
to explicitly use a known-good configuration.
In the long run someone should inspect these cases one-by-one and fix
them where appropriate. But that is probably better managed as part of a
larger effort to tidy up nulls in WALA. I'm not planning to take that on
now or any time soon, though, so this is a better setup for now.
Ben Liblit
Manu Sridharan
Julian Dolby
Brian Alliet
Martin Mohr
Juergen Graf
Manu Sridharan
Julian Dolby