[Lldb-commits] [lldb] 466ea89 - [lldb] Fix failures when evaluating C++ expression and loading modules

[Med Ismail Bennani via lldb-commits]

Author: Med Ismail Bennani
Date: 2023-09-29T18:56:02-07:00
New Revision: 466ea89fc6d8bfd197cbc1055bbc38e730e9d523

URL: https://github.com/llvm/llvm-project/commit/466ea89fc6d8bfd197cbc1055bbc38e730e9d523
DIFF: https://github.com/llvm/llvm-project/commit/466ea89fc6d8bfd197cbc1055bbc38e730e9d523.diff

LOG: [lldb] Fix failures when evaluating C++ expression and loading modules

This patch tentatively fixes the various test failures introduced
following 0ea3d88bdb16:

https://green.lab.llvm.org/green/view/LLDB/job/as-lldb-cmake/6316/

>From my understanding, the main issue here is that we can't find some headers
when evaluating C++ expressions since those headers have been promoted
to be system modules, and to be shipped as part of the toolchain.

Prior to 0ea3d88bdb16, the `BuiltinHeadersInSystemModules` flag for in
the clang `LangOpts` struct was always set, however, after it landed,
the flag becomes opt-in, depending on toolchain that is used with the
compiler instance. This gets set in `clang::createInvocation` down to
`Darwin::addClangTargetOptions`, as this is used mostly on Apple platforms.

However, since `ClangExpressionParser` makes a dummy `CompilerInstance`,
and sets the various language options arbitrarily, instead of using the
`clang::createInvocation`, the flag remains unset, which causes the
various error messages:

```
AssertionError: 'error: module.modulemap:96:11: header 'stdarg.h' not found
   96 |    header "stdarg.h" // note: supplied by the compiler
      |           ^
```

Given that this flag was opt-out previously, this patch brings back that
behavior by setting it in lldb's `ClangExpressionParser` constructor,
until we actually decide to pull the language options from the compiler driver.

Signed-off-by: Med Ismail Bennani <ismail at bennani.ma>

Added: 
    

Modified: 
    lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
index aee0f1f56ec74b5..f6856b1a2558cbc 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -575,6 +575,7 @@ ClangExpressionParser::ClangExpressionParser(
     lang_opts.GNUMode = true;
     lang_opts.GNUKeywords = true;
     lang_opts.CPlusPlus11 = true;
+    lang_opts.BuiltinHeadersInSystemModules = true;
 
     // The Darwin libc expects this macro to be set.
     lang_opts.GNUCVersion = 40201;