<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Clang crashes on code completion in comment [clang::Lexer::Lex (this=0x0, Result=...), clang::Preprocessor::Lex (this=0x450df0, Result=...)]"
   href="https://bugs.llvm.org/show_bug.cgi?id=32732">32732</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Clang crashes on code completion in comment [clang::Lexer::Lex (this=0x0, Result=...), clang::Preprocessor::Lex (this=0x450df0, Result=...)]
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>C++
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>kfunk@kde.org
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>LLVM @ <a href="https://llvm.org/svn/llvm-project/llvm/trunk@300096">https://llvm.org/svn/llvm-project/llvm/trunk@300096</a>
Clang @ <a href="https://llvm.org/svn/llvm-project/cfe/trunk@300074">https://llvm.org/svn/llvm-project/cfe/trunk@300074</a>

I can reproduce the crash with Clang 3.8/3.9/4.0 & current trunk.

Test case:
% cat ~/test5.c 
#include "test5.h"

% cat ~/test5.h 
#pragma once

struct a {
  /* <CURSOR_HERE> */
  struct {
  } b;
};

% clang++ -cc1 -xc -fsyntax-only -code-completion-at /home/kfunk/test5.h:4:7
/home/kfunk/test5.c

Backtrace:
Thread 1 (Thread 0x7ffff3125740 (LWP 23633)):
#0  clang::Lexer::Lex (this=0x0, Result=...) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Lex/Lexer.cpp:2912
#1  0x00007ffff415bd24 in clang::Preprocessor::Lex (this=0x450df0, Result=...)
at /home/kfunk/devel/src/llvm/tools/clang/lib/Lex/Preprocessor.cpp:745
#2  0x00007ffff3f92306 in clang::Parser::ConsumeToken (this=0x498000) at
/home/kfunk/devel/src/llvm/tools/clang/include/clang/Parse/Parser.h:313
#3  clang::Parser::ParseDeclOrFunctionDefInternal (this=0x498000, attrs=...,
DS=..., AS=clang::AS_none) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Parse/Parser.cpp:932
#4  0x00007ffff3f91f69 in clang::Parser::ParseDeclarationOrFunctionDefinition
(this=0x498000, attrs=..., DS=<optimized out>, AS=clang::AS_none) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Parse/Parser.cpp:1001
#5  0x00007ffff3f91564 in clang::Parser::ParseExternalDeclaration
(this=0x498000, attrs=..., DS=0x0) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Parse/Parser.cpp:851
#6  0x00007ffff3f906d7 in clang::Parser::ParseTopLevelDecl (this=0x498000,
Result=...) at /home/kfunk/devel/src/llvm/tools/clang/lib/Parse/Parser.cpp:624
#7  0x00007ffff3f90139 in clang::Parser::ParseFirstTopLevelDecl (this=0x498000,
Result=...) at /home/kfunk/devel/src/llvm/tools/clang/lib/Parse/Parser.cpp:558
#8  0x00007ffff3f08975 in clang::ParseAST (S=..., PrintStats=<optimized out>,
SkipFunctionBodies=<optimized out>) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Parse/ParseAST.cpp:146
#9  0x00007ffff608975f in clang::FrontendAction::Execute (this=0x44e1f0) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Frontend/FrontendAction.cpp:512
#10 0x00007ffff604d288 in clang::CompilerInstance::ExecuteAction
(this=0x44bf80, Act=...) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Frontend/CompilerInstance.cpp:969
#11 0x00007ffff5fd57c1 in clang::ExecuteCompilerInvocation (Clang=<optimized
out>) at
/home/kfunk/devel/src/llvm/tools/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:249
#12 0x000000000040def1 in cc1_main (Argv=..., Argv0=<optimized out>,
MainAddr=<optimized out>) at
/home/kfunk/devel/src/llvm/tools/clang/tools/driver/cc1_main.cpp:221
#13 0x000000000040c669 in ExecuteCC1Tool (Tool=..., argv=...) at
/home/kfunk/devel/src/llvm/tools/clang/tools/driver/driver.cpp:299
#14 main (argc_=<optimized out>, argv_=<optimized out>) at
/home/kfunk/devel/src/llvm/tools/clang/tools/driver/driver.cpp:380

This seems to cause frequent crashes inside KDevelop. See downstream bug
report:
  <a href="https://bugs.kde.org/show_bug.cgi?id=372686">https://bugs.kde.org/show_bug.cgi?id=372686</a></pre>
        </div>
      </p>


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