<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Jun 6, 2014 at 4:48 PM, Alex Horn <span dir="ltr"><<a href="mailto:alex.horn@cs.ox.ac.uk" target="_blank">alex.horn@cs.ox.ac.uk</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">> [...] Why not write all tools to work on the non-macro-rewritten code?<br>
<div class="">> (you can get macros yourself via the PPCallbacks interface).<br>
<br>
</div>As far as I understand, PPCallbacks operate on a different level of<br>
abstraction than ASTMatchers. The RefactoringTool I have in mind<br>
rewrites two things: (1) "assert()" macros and (2) control-flow<br>
conditions in "if-then-else", "while" and "for" statements. The<br>
rewriting of both (1) and (2) is now implemented as ASTMatchers.<br>
Unfortunately, (2) does not work correctly unless macros are rewritten<br>
beforehand. To see this, consider "#define compare(a, b) do { if ((a)<br>
< (b)) swap(a, b) } while(0);".<br></blockquote><div><br></div><div>I'm considering it :) So what's the problem rewriting this inside the macro?</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I presumed for now that it does not make sense, generally speaking, to<br>
invoke ASTMatchers from within PPCallbacks because the source code<br>
inside a macro definition may not be well-formed. This is why I was<br>
merely looking for a way to combine ASTMatchers and cc1 drivers.<br></blockquote><div><br></div><div>No, my idea on how to use PPCallbacks was to just use them to collect information about the macros, and then use that information to generate the replacements.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Best,<br>
Alex<br>
<div class="HOEnZb"><div class="h5"><br>
On 6 June 2014 15:13, Manuel Klimek <<a href="mailto:klimek@google.com">klimek@google.com</a>> wrote:<br>
> On Fri, Jun 6, 2014 at 4:10 PM, Alex Horn <<a href="mailto:alex.horn@cs.ox.ac.uk">alex.horn@cs.ox.ac.uk</a>> wrote:<br>
>><br>
>> Thanks for the effective response. This helped on the right track and<br>
>> I've successfully used SourceManager::getImmediateExpansionRange() to<br>
>> insert BAR and its surrounding parenthesis correctly.<br>
>><br>
>> As a directly related issue: The proposed technique of using the<br>
>> expansion range does the trick but of course requires that "-cc1<br>
>> -rewrite-macros" is _not_ invoked prior to rewriting "assert()"<br>
>> macros. However, this is problematic when other rewrites in the same<br>
>> RefactoringTool _do_ rely on macros having been rewritten. This poses<br>
>> the question whether these things can coexist in the same<br>
>> RefactoringTool. In particular, is it possible to call the<br>
>> RewriteMacros functionality only after certain matches have completed?<br>
>><br>
>> To ask the same thing differently, what is the preferred way to<br>
>> compose ASTMatchers and cc1 drivers such as RewriteMacros?<br>
><br>
><br>
> I wouldn't combine them. Why not write all tools to work on the<br>
> non-macro-rewritten code? (you can get macros yourself via the PPCallbacks<br>
> interface).<br>
><br>
>><br>
>><br>
>> On 6 June 2014 13:56, Manuel Klimek <<a href="mailto:klimek@google.com">klimek@google.com</a>> wrote:<br>
>> > On Tue, Jun 3, 2014 at 5:36 PM, Alex Horn <<a href="mailto:alex.horn@cs.ox.ac.uk">alex.horn@cs.ox.ac.uk</a>> wrote:<br>
>> >><br>
>> >> Hello,<br>
>> >><br>
>> >> I am struggling to replace "assert(c)" macro calls by "BAR(c)" where c<br>
>> >> is some integer expression and BAR is a function.<br>
>> >><br>
>> >> The problem manifests itself in RefactoringTool::applyAllReplacements<br>
>> >> which returns false, thereby causing the tool to skip replacements.<br>
>> >><br>
>> >> I am using the following ASTMatcher:<br>
>> >><br>
>> >> StatementMatcher makeAssertMatcher() {<br>
>> >> return<br>
>> >><br>
>> >> callExpr(callee(functionDecl(hasName("__builtin_expect")))).bind("AssertBindId");<br>
>> >> }<br>
>> >><br>
>> >> Note: callExpr(callee(functionDecl(hasName("assert"))) won't work here<br>
>> >> because assert() is a macro according to the assert.h and cassert<br>
>> >> headers.<br>
>> >><br>
>> >> Here's an example match using clang-query:<br>
>> >><br>
>> >> example.cpp:<br>
>> >><br>
>> >> #include <assert.h><br>
>> >> int main() {<br>
>> >> assert(false);<br>
>> >> return 0;<br>
>> >> }<br>
>> >><br>
>> >> $ clang-query> match<br>
>> >> callExpr(callee(functionDecl(hasName("__builtin_expect"))))<br>
>> >><br>
>> >> Match #1:<br>
>> >><br>
>> >> example.cpp:4:3: note: "AssertBindId" binds here<br>
>> >> assert(false);<br>
>> >> ^~~~~~~~~~~~~<br>
>> >> /usr/include/assert.h:93:6: note: expanded from macro 'assert'<br>
>> >> (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__,<br>
>> >> __LINE__, #e) : (void)0)<br>
>> >> ^~~~~~~~~~~~~~~~~~~~~~~~~<br>
>> >> 1 match.<br>
>> >><br>
>> >> But I cannot find the correct way to rewrite the match; the following<br>
>> >> replacement is skipped (i.e. see line 295 in Refactoring.cpp):<br>
>> >><br>
>> >> const CallExpr *E = Result.Nodes.getNodeAs<CallExpr>("AssertBindId");<br>
>> >> SourceManager &SM = *Result.SourceManager;<br>
>> >> SourceLocation LocBegin = E->getLocStart();<br>
>> >> Replace->insert(tooling::Replacement(SM, LocBegin,<br>
>> >> /* number of letters in assert */ 6, "BAR"));<br>
>> >><br>
>> >> What is the correct way (if any) to rewrite call expressions of macros<br>
>> >> such as "assert()"?<br>
>> ><br>
>> ><br>
>> > You need to get the expansion location:<br>
>> > SourceLocation ExpLocBegin = SM.getExpansionLoc(LocBegin);<br>
>> > Replace->insert(tooling::Replacement(SM, ExpLocBegin, 6, "BAR"));<br>
>> ><br>
>> > Something like this should do the trick...<br>
>> > Cheers,<br>
>> > /Manuel<br>
><br>
><br>
</div></div></blockquote></div><br></div></div>