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Ah, my memory of a surgeonfish never fails me.<br>
Yeah, i guess just take it over.<br>
<br>
<div class="moz-cite-prefix">On 10/25/18 2:55 AM, Gábor Horváth
wrote:<br>
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<div dir="ltr">Given the lack of recent activity feel free to
commandeer the revision. I think it should be quite close to be
merged.<br>
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<div dir="ltr">On Thu, 25 Oct 2018 at 10:30, Alexander Zaitsev
<<a href="mailto:zamazan4ik@tut.by" moz-do-not-send="true">zamazan4ik@tut.by</a>>
wrote:<br>
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<p>Didn't know that this check is already implemented. I
think I can continue this work (seems like original author
of the change don't work on it now). What do you think?<br>
</p>
<div class="m_3497051423702866874moz-cite-prefix">25.10.2018
6:34, Gábor Horváth пишет:<br>
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<div dir="auto">Hi!
<div dir="auto"><br>
</div>
<div dir="auto">Do you have something in mind like
this: <a href="https://reviews.llvm.org/D33672"
target="_blank" moz-do-not-send="true">https://reviews.llvm.org/D33672</a>
?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Regards,</div>
<div dir="auto">Gábor</div>
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<br>
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<div dir="ltr">Artem Dergachev via cfe-dev <<a
href="mailto:cfe-dev@lists.llvm.org" target="_blank"
moz-do-not-send="true">cfe-dev@lists.llvm.org</a>>
ezt írta (időpont: 2018. okt. 25., Cs 4:32):<br>
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<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
<br>
Your overall plan sounds good, and i believe that such
checker will be <br>
very useful, i'd love to have such check in the
analyzer. If you want to <br>
post it upstream, i encourage you to start early by
publishing <br>
prototypes on Phabricator for code reviews, even when
you think they're <br>
not ready, just because code reviews are cool!<br>
<br>
Path-sensitive analysis is indeed useful here because
sometimes it's not <br>
immediately obvious from the code which values are
possible for the <br>
sub-expression. Defining the buggy state can be a bit
annoying because <br>
enum values can be non-contiguous and/or numerous; the
former means that <br>
you'll potentially need to make a lot of
State->assume(...) calls and <br>
see if none of the states with assumptions are null;
the latter means <br>
that you'll need to make sure you identify segments of
values to avoid <br>
calling assume() for *every* enum item. I also
recommend <br>
ConstraintManager::assumeInclusiveRange() for direct
assumptions over <br>
segments.<br>
<br>
Your questions so far are AST questions, not specific
to the analyzer. <br>
First of all, notice that every expression has a
(qualified) type, which <br>
is the type of the value it evaluates to, and it can
always be obtained <br>
via Expr::getType(). It may be void (eg., call
expression for a function <br>
that returns void), but it's always there.<br>
<br>
For cast-expression, as you might have already
guessed, the type of the <br>
expression is the target type of the cast. Because,
well, that's the <br>
whole point of the cast. This takes care of question
2.<br>
<br>
Most functions return not raw Types but QualType
objects that are types <br>
with qualifiers. You can always use the overloaded
operator->() on the <br>
QualType to access the underlying Type; there's also <br>
QualType::getTypePtr(), but if you think you need it -
most likely you <br>
don't.<br>
<br>
Now, types, like statements or declarations, are a
hierarchy. Some types <br>
are integer types, some are array or structure types,
some are enum <br>
types. Enum types are represented by the EnumType
class, to which you <br>
can try to dyn_cast<>() your type. Or, even
better, use Type::getAs<>(), <br>
which can be accessed directly with operator->() on
QualType.<br>
<br>
If dyn_cast<>()/getAs<>() is successful -
your type is an enum and you <br>
have a pointer to an EnumType object, so you can call
<br>
EnumType::getDecl() to find the *declaration* of the
enum in the code.<br>
<br>
Also if the enum hides under a typedef, then the type
wouldn't be an <br>
EnumType but it'd be a TypedefType, so the cast would
fail. The easy way <br>
to get rid of typedefs is to do
QualType::getCanonicalType().<br>
<br>
Some declarations are forward declarations. You might
need to do <br>
EnumDecl::getDefinition() to find the actual
definition. Maybe you don't <br>
need that: i don't remember what operations are
allowed on incomplete <br>
enum types.<br>
<br>
Once you have your EnumDecl that is the definition,
you can iterate over <br>
EnumDecl::enumerators() to see what values are
present.<br>
<br>
In Clang there are a lot more cast kinds of
expressions than you <br>
probably expect, so you might want to take a look at
the list of casts <br>
in clang/AST/OperationKinds.def and see which ones do
you need; i don't <br>
think it'll be important at first, but just in case.<br>
<br>
In order to quickly catch up on the basics, i also
recommend the AST <br>
tutorial by Manuel Klimek at <a
href="https://www.youtube.com/watch?v=VqCkCDFLSsc"
rel="noreferrer noreferrer" target="_blank"
moz-do-not-send="true">https://www.youtube.com/watch?v=VqCkCDFLSsc</a><br>
<br>
<br>
On 10/24/18 5:16 PM, Alexander Zaitsev via cfe-dev
wrote:<br>
><br>
> Hello. I am newbie in Clang Static Analyzer and I
am trying to write <br>
> new Clang Static Analyzer check, which is aimed
to find issues with <br>
> casting values to enum: if we cast anything which
is no presented in <br>
> target enum it will be unspecified/undefined
behavior(depends on C++ <br>
> version).<br>
><br>
> So my plan is:<br>
><br>
> 1. Find all casts in source code. Seems like<br>
> 'check::PreStmt<CastExpr>>' it's
what I need.<br>
> 2. In my implementation of `checkPreStmt` method
I must get target<br>
> type from CastExpr, but I don't know, how to
do it - can you help<br>
> with it?<br>
> 3. Then if target type in Cast is Enum, I must
get all values from<br>
> this Enum and compare it with all possible
values which can be<br>
> presented by CastExpr->getSubExpr() - here
I don't know how to<br>
> evaluate CastExpr->getSubExpr() and how to
get all values from Enum.<br>
><br>
> Do you have any ideas?<br>
><br>
> -- <br>
> Best regards,<br>
> Alexander Zaitsev<br>
><br>
><br>
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<pre class="m_3497051423702866874moz-signature" cols="72">--
Best regards,
Alexander Zaitsev</pre>
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