[llvm-bugs] [Bug 46131] New: libclang crash on lambda capture using deleted copy constructor

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=46131

            Bug ID: 46131
           Summary: libclang crash on lambda capture using deleted copy
                    constructor
           Product: clang
           Version: 10.0
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: libclang
          Assignee: unassignedclangbugs at nondot.org
          Reporter: f.dennemont at gmail.com
                CC: klimek at google.com, llvm-bugs at lists.llvm.org,
                    richard-llvm at metafoo.co.uk

Created attachment 23554
  --> https://bugs.llvm.org/attachment.cgi?id=23554&action=edit
The file that crashes libclang.

== Overview
When using libclang to parse the attached C++ file, it crashes. The C++ file
simply contains a lambda definition that captures by copy an object that has a
deleted copy constructor.

== Steps to Reproduce
1. Download the attached file.
2. Use libclang to parse that file. I use a simple code similar to this for the
parsing :
//---
ClangIndex = createIndex(false, false);
unsigned int options =
CXTranslationUnit_DetailedPreprocessingRecord|CXTranslationUnit_KeepGoing;
char const* const flags = ["-w", "-O0", "--std=c++17", "-c",
"--target=i686-pc-win32", "-fexceptions", "-fno-rtti", "-undef",
"-ferror-limit=100000", "-xc++", "-fshort-wchar",
"-Wno-dollar-in-identifier-extension"];
TU = parseTranslationUnit(ClangIndex, BuildOptions.szFileName, flags,
sizeof(flags)/sizeof(*Flags), Ocp.UnsavedFiles, Ocp.UnsavedFileCount, options);
CXCursor startCursor = getTranslationUnitCursor(TU);
visitChildren(startCursor, buildTree, &Datas);
//---

== Actual Results
The application crashed.

== Expected Results
No crash and libclang gives a diagnostic with a message similar to "call to a
deleted copy constructor".

== Build Date & Hardware
2020-05-29 on Windows 7.

== libclang version : 10 (on that commit :
https://github.com/llvm/llvm-project/commit/92d5c1be9ee93850c0a8903f05f36a23ee835dc2)


== Additional Information
I fixed the bug locally by simply ignoring a null pointer, like this :
in clang/tools/libclang/CIndex.cpp line 3174 :
        // Visit init captures
        for (auto InitExpr : E->capture_inits()) {
-          if (Visit(InitExpr))
+          if (InitExpr && Visit(InitExpr))
            return true;
        }

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