<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">A general thought:</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">What makes this perhaps unnecessarily difficult is that ASTConsumer does not provide a full suite of overrideable `Handle*` functions to be called in the midst of parsing.</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">There is `HandleTranslationUnit()` (called after the full translation unit has been parsed), `HandleTopLevelDecl()` (called after each top-level decl is parsed), and the remainder seem to be assorted special cases (`HandleInterestingDecl()` etc).</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">If there were e.g. `HandleCXXThisExpr(CXXThisExpr *E)` et al, called while `E`’s proper scope/state data is still active, Oleksandr could define his logic in an override of that, within which he could simply call `S.LookupName(Result, S.getCurScope())` to get his lookup results. No need to copy and paste implementation details to reenter the proper scope/state.</div><p style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class="webkit-block-placeholder"></p><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">Re how it could be implemented to minimize overhead:</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">```</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">// — ASTConsumer.h — //</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">class AbstractDeclHandler {…}; // Like DeclVisitor but using virtuals instead of CRTP</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">class AbstractStmtHandler {…}; //""</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">class AbstractExprHandler {</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> … //e.g.:</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> virtual bool HandleCXXThisExpr(Expr *E) { return true; }</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> …</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">};</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">class ASTConsumer {</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> AbstractDeclHandler *DH = nullptr;</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> AbstractStmtHandler *SH = nullptr;</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> AbstractExprHandler *EH = nullptr;</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">public:</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> //getDeclHandler/setDeclHandler/et al</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> …</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">};</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">// - lib/Sema/… - //</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">ExprResult Sema::BuildCXXThisExpr(…) {</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> ExprResult res = …;</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> if (auto *Handler = Consumer.getExprHandler())</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> if (!Handler->HandleCXXThisExpr(res.get()))</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> return ExprError();</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> return res;</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">}</div><div style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;" class="">// same for other Stmts & Decls: always Handle* after building</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">```</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">To further reduce overhead: "handling" Exprs immediately upon building is too fine-grained — probably only need to handle Stmts and Decls immediately after building them, and group the Expr handling calls together in the handling of their parent Stmt.</div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><br class=""></div><div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">But this at least demonstrates how a user override called in this way would have access to all the proper scope/state info originally available to the node, which could be a very useful addition to ASTConsumer.</div><div><br class=""><blockquote type="cite" class=""><div class="">On Oct 4, 2020, at 3:15 AM, Vassil Vassilev via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" class="">cfe-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
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<div class="">
<div class="moz-cite-prefix">On 10/3/20 3:40 PM, Oleksandr Koval via
cfe-dev wrote:<br class="">
</div>
<blockquote type="cite" cite="mid:CAGatSHGuxARpSxiESd60Q_5AJbmbCDXuGjCQ6Yq8Cg+A5mL+jw@mail.gmail.com" class="">
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<div class="">Hi, I'm writing a check that detects and removes redundant
`this->` usage. Finding explicit `this->` was simple,
now I want to check whether it's safe to remove it. My main
concern is such case:</div>
<pre style="background-image: none; background-attachment: scroll; background-color: rgb(255, 255, 255); background-position: 0% 0%; background-repeat: repeat repeat;" class=""><span style="color:rgb(128,0,0);font-weight:bold" class="">struct</span> X<span style="color:rgb(128,0,128)" class="">{</span>
<span style="color:rgb(128,0,0);font-weight:bold" class="">void</span> f<span style="color:rgb(128,128,48)" class="">(</span><span style="color:rgb(128,0,0);font-weight:bold" class="">int</span> x<span style="color:rgb(128,128,48)" class="">)</span><span style="color:rgb(128,0,128)" class="">{</span>
<span style="color:rgb(105,105,105)" class="">// without `this->` will use parameter</span>
<span style="color:rgb(128,0,0);font-weight:bold" class="">this</span><span style="color:rgb(128,128,48)" class="">-</span><span style="color:rgb(128,128,48)" class="">></span>x<span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,0,128)" class="">;</span>
<span style="color:rgb(105,105,105)" class="">// can remove `this->` because</span>
<span style="color:rgb(105,105,105)" class="">// local `y` is not visible yet</span>
<span style="color:rgb(128,0,0);font-weight:bold" class="">this</span><span style="color:rgb(128,128,48)" class="">-</span><span style="color:rgb(128,128,48)" class="">></span>y<span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,0,128)" class="">;</span>
y<span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,0,128)" class="">;</span>
<span style="color:rgb(128,0,0);font-weight:bold" class="">int</span> y<span style="color:rgb(128,0,128)" class="">;</span>
y<span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,128,48)" class="">+</span><span style="color:rgb(128,0,128)" class="">;</span>
<span style="color:rgb(128,0,128)" class="">}</span>
<span style="color:rgb(128,0,0);font-weight:bold" class="">int</span> x<span style="color:rgb(128,0,128)" class="">;</span>
<span style="color:rgb(128,0,0);font-weight:bold" class="">int</span> y<span style="color:rgb(128,0,128)" class="">;</span>
<span style="color:rgb(128,0,128)" class="">}</span><span style="color:rgb(128,0,128)" class="">;</span>
</pre>
<div class="">I need to know whether a specific name(function or
variable) will resolve to the same declaration without
`this->` part. My matcher is <i class="">memberExpr(has(cxxThisExpr()))</i>,
I bind MemberExpr and CXXThisExpr, I can rewrite matcher to
also bind enclosing CXXMethodDecl. As I understand, simple
enumeration of parameter/local variable names won't work(as in
case with `y`) because of lookup/visibility rules. Is there
some `lookup()` function whose result I can compare against
the declaration of original function/variable? I found
Sema::LookupName() but can't figure out how to get Scope of
the found expression. Can you give me an example please?<br class="">
</div>
</div>
</blockquote><p class=""><br class="">
</p><p class=""> The Scope is a parser thing which contains an opaque ptr to the
DeclContext. In principle, you can create a fake Scope and attach
the relevant DeclContext via setEntity. I think just passing
Sema::TUScope may work. If you want some pseudocode:</p><p class=""> Scope *fakeS = new Scope(...);<br class="">
fakeS->setEntity(DC);<br class="">
// you may need to do some work for the variable shadowing<br class="">
LookupResult R(Sema, Var->getName(), SourceLocation(),
Sema::LookupOrdinaryName, Sema::ForRedeclaration);<br class="">
Sema->LookupName(R, fakeS);<br class="">
delete fakeS;</p><p class=""> Note that is an approximation as we do not attach the scope to
the chain of scopes like the parser does. It some extra work that
is also possible.</p><p class=""><br class="">
</p>
<blockquote type="cite" cite="mid:CAGatSHGuxARpSxiESd60Q_5AJbmbCDXuGjCQ6Yq8Cg+A5mL+jw@mail.gmail.com" class="">
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<div class=""><br class="">
</div>
<div class="">-- <br class="">
<div dir="ltr" data-smartmail="gmail_signature" class="">
<div dir="ltr" class="">
<div class="">Regards,</div>
<div class="">Oleksandr Koval.<br class="">
</div>
</div>
</div>
</div>
</div>
<br class="">
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</blockquote><p class=""><br class="">
</p>
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