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Re: [cdt-dev] PDOMWriter and IncludeInformation

I've created 413768, and am working on a junit to reproduce the problem.


On 13-07-25 04:11 PM, Andrew Eidsness wrote:
> Summary:
> I have a source file with two #include statements. The PDOMFile that is created has a list of three PDOMIncludes. This
> doesn't seem valid, I think the conditional on line 601 of PDOMWriter is backward:
> |
> 600: for (ISignificantMacros sig : stmt.getLoadedVersions()) {
> 601:     if (!sig.equals(mainSig)) {
> 602:         includeInfos.add(new IncludeInformation(stmt, targetLoc, sig, false));
> 603:     }
> 604: }
> 605: final boolean isContext = stmt.isActive() && stmt.isResolved() &&
> 606:         (data.fContextIncludes.contains(stmt) || isContextFor(oldFile, stmt));
> 607: includeInfos.add(new IncludeInformation(stmt, targetLoc, mainSig, isContext));|
> It would make sense to me if that condition were saying “If there is already an IncludeInfo and its significant macros
> are the same as what is needed, then reuse that IncludeInfo.”
> The part of the hypothesis that confuses me is line 607. It seems that if things really are as simple as that, then
> there should be something to ensure that only one of 601 and 607 are executed. Also, the loop on line 600 should be
> aborted when an existing IncludeInfo is chosen.
> Are there cases where there should be more than one IncludeInformation for a single #include directive?
> I‘ll create a bug to track this. I’m sending the email now in case someone can correct my logic. I don‘t really
> understand the pragma-once handling which is what the code’s checkin comment references.
> The rest of this (long) email describes how I got to this point.
> Details:
> This test code has been reduced from larger files.
> |src.c:
> #include "h1.h"
> #include "h2.h"
> int m1 = MACRO; // ProblemBinding for MACRO
> h1.h:
> #ifndef H1
> #define H1
> #include "h1a.h" // line 5 (see below)
> #undef D1
> #include "h1a.h" // line 7 (see below)
> #endif
> h1a.h:
> extern int i;
> #ifndef H1a
> #define H1a
> #define D1
> #endif
> h2.h:
> #define MACRO 1
> #ifdef D1
> #endif|
> With the current implementation the reference to MACRO is not resolved in src.c and there is a ProblemBinding in the
> initialization clause.
> Here is a trace of the PDOMIncludes that are stored into the PDOMFile for h1.h:
> PDOMFile(5498) /JI449520-C2/src/h1.h {}
> PDOMInclude(5802) stmt-line 5 ‘#include “h1a.h”’ -> PDOMFile(4506)
> PDOMInclude(5834) stmt-line 7 ‘#include “h1a.h”’ -> PDOMFile(4506)
> PDOMInclude(5866) stmt-line 7 ‘#include “h1a.h”’ -> PDOMFile(5330)
> I think that the first and third PDOMInclude instances are valid, but the second one is not.
> The trouble with the second instance is that it is created from the #include on line 7, but it points to the PDOMFile
> that has the same context as the #include on line 5.
> The reason this causes the problem binding is as follows.
> h2.h is stored into the index with D1 being a significant macro. The CPreprocessor.fCurrentContext says that D1 is
> undefined at this point (from line 6 of h1.h). The index lookup code ensures that h2.h will only be used in contexts
> where D1 is not defined.
> h1a.h is stored into the index two times. The first time the fCurrentContext says that H1a is not defined, the second
> time it says that H1a is defined. The first version of the file has the directive #define D1, the second version does not.
> When CReconciler processes the #include‘s in src.c is has problems while processing h1.h. It processes the first
> instance of h1a.h including the #define’s D1; D1 is added to the fMacroDictionary. Good.
> Then it processes the #undef D1 and removes the value. Good.
> Then it processes the first instance of h1a.h again. This puts D1 back into the fMacroDictionary. Oh-oh.
> Later the processor tries to handle h2.h. The version of this file that is in the index requires D1 to be undefined —
> which it is not. We don't get to use the indexed version of h2.h and have to look at the source code. However,
> PREF_USE_STRUCTURAL_PARSE_MODE is set to false, so it ignores the content of the file. The #define MACRO directive is
> not found.
> -Andrew
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