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    <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 - lld-link reporting undefined symbol with lto"
   href="https://bugs.llvm.org/show_bug.cgi?id=42536">42536</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>lld-link reporting undefined symbol with lto
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>lld
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

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

        <tr>
          <th>OS</th>
          <td>Windows NT
          </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>COFF
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>russell_gallop@sn.scee.net
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=22205" name="attach_22205" title="Reproducible">attachment 22205</a> <a href="attachment.cgi?id=22205&action=edit" title="Reproducible">[details]</a></span>
Reproducible

lld-link 8.0.0 crashes when reporting an undefined symbol (still present at
r364942).

(note that the test case below wouldn't link successfully with the bug fixed
due to the undefined symbols).

--- library.cpp
struct S {
  virtual void foo() {}
};
void a() { S b; }

--- main.cpp
struct __declspec(dllimport) S {
  virtual void foo();
};
struct a {
  a();
};
struct {
  a b;
  S c;
} d;

<span class="quote">> clang-cl /c /nologo /O2 /MT /TP -m64 -flto library.cpp
> llvm-lib /OUT:library.lib /NOLOGO library.obj
> clang-cl /c /nologo /O2 /MT /TP -m64 -flto main.cpp
>lld-link /OUT:test.exe "library.lib" "main.obj" /MACHINE:X64 /INCREMENTAL:NO /SUBSYSTEM:CONSOLE /ERRORREPORT:PROMPT /NOLOGO /NODEFAULTLIB</span >
lld-link: error: <root>: undefined symbol: mainCRTStartup
Stack dump:
0.      Program arguments: lld-link /OUT:test.exe library.lib main.obj
/MACHINE:X64 /INCREMENTAL:NO /SUBSYSTEM:CONSOLE /ERRORREPORT:PROMPT /NOLOGO
/NODEFAULTLIB
 #0 0x00007ff6b77886d3 lld::coff::getSymbol
F:\git\llvm-project\lld\COFF\SymbolTable.cpp:72:0
 #1 0x00007ff6b7787c0c lld::coff::getSymbolLocations(class lld::coff::ObjFile
*,unsigned int) F:\git\llvm-project\lld\COFF\SymbolTable.cpp:102:0
 #2 0x00007ff6b778bcaf lld::coff::reportUndefinedSymbol
F:\git\llvm-project\lld\COFF\SymbolTable.cpp:147:0
 #3 0x00007ff6b778b498 lld::coff::SymbolTable::reportRemainingUndefines(void)
F:\git\llvm-project\lld\COFF\SymbolTable.cpp:331:0
 #4 0x00007ff6b76f0437 lld::coff::LinkerDriver::link(class llvm::ArrayRef<char
const *>) F:\git\llvm-project\lld\COFF\Driver.cpp:1761:0
 #5 0x00007ff6b76e89e1 lld::coff::link(class llvm::ArrayRef<char const
*>,bool,class llvm::raw_ostream &) F:\git\llvm-project\lld\COFF\Driver.cpp:78:0
 #6 0x00007ff6b76b1227 main F:\git\llvm-project\lld\tools\lld\lld.cpp:155:0
 #7 0x00007ff6b95fbc94 __scrt_common_main_seh
d:\agent\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288:0
 #8 0x00007ffe2d414034 (C:\WINDOWS\System32\KERNEL32.DLL+0x14034)
 #9 0x00007ffe2e553691 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x73691)

Without -flto this reports:
lld-link: error: <root>: undefined symbol: mainCRTStartup
lld-link: error: undefined symbol: public: __cdecl a::a(void)
<span class="quote">>>> referenced by main.obj:(_GLOBAL__sub_I_main.cpp)</span >

lld-link: error: undefined symbol: const type_info::`vftable'
<span class="quote">>>> referenced by main.obj:(struct S `RTTI Type Descriptor')
>>> referenced by library.lib(library.obj)</span ></pre>
        </div>
      </p>


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