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c++clanglibclanglibtooling

Reparse an ASTUnit with relative header include paths fails

I'm using libclang's LibTooling to get code completion data from C++ source files. The ASTUnits are generated from a compile_commands.json file created via CMake with Ninja as the generator.

In the compiler invocation commands, there are relative header include paths (such as -Ifoo -I../bar).

To successfully generate a clang::ASTUnit, I need to set clang::FileManager::FileSystemOptions::WorkingDir to instruct clang on how to canonicalise the relative paths.

Problem is, when calling clang::ASTUnit::Reparse() on my ASTUnits, this value is discarded and my clang::DiagnosticConsumer then reports missing header files.

As a workaround, I'm regenerating the ASTUnits from scratch instead of reparsing them when the sources changes.

Questions:

Q1: Is this normal behavior ? For me it essencialy makes Reparse useless.
Q2: How to successfully reparse an ASTUnit with relative header include paths ?

Solution

  • Follow-up : Using Clang/LLVM 4.0.0, it is not possible to reparse an ASTUnit which compiler invocation contains relative include paths.

    Starting from 5.0.0 however, clang::ASTUnit::Reparse contains a third argument that allows to pass a clang::vfs::FileSystem object that can solve this problem.