This is the reduced output generated by llvm-dwarfdump:

-----------------------------------------------------------------
inlined-dwarf.o:	file format ELF64-x86-64

.debug_info contents:

DW_TAG_compile_unit

  DW_TAG_subprogram
    DW_TAG_formal_parameter
      DW_AT_abstract_origin	(0x00000074 "Param")
    DW_TAG_variable
      DW_AT_abstract_origin	(0x0000007f "Var_1")
    DW_TAG_lexical_block
      DW_TAG_variable
        DW_AT_abstract_origin	(0x0000008b "Var_2")

  DW_TAG_subprogram
    DW_AT_name	("InlineFunction")
    DW_TAG_formal_parameter
      DW_AT_name	("Param")
    DW_TAG_variable
      DW_AT_name	("Var_1")
    DW_TAG_lexical_block
      DW_TAG_variable
        DW_AT_name	("Var_2")

  DW_TAG_subprogram
    DW_AT_name	("testInlined")
    DW_TAG_formal_parameter
      DW_AT_name	("Param_1")
    DW_TAG_formal_parameter
      DW_AT_name	("Param_2")
    DW_TAG_variable
      DW_AT_name	("A")

    DW_TAG_inlined_subroutine
      DW_TAG_formal_parameter
        DW_AT_abstract_origin	(0x00000074 "Param")
      DW_TAG_variable
        DW_AT_abstract_origin	(0x0000007f "Var_1") <------ (*)
      DW_TAG_lexical_block
        DW_TAG_variable
          DW_AT_abstract_origin	(0x0000008b "Var_2") <------ (*)
-----------------------------------------------------------------

(*) Var_1 and Var_2 are at different lexical scopes.

This is the reduced output generated by llvm-readobj:

outline copy (inlineFunction)
-----------------------------------------------------------------

  Subsection [
    ...
    GlobalProcIdSym {
      Kind: S_GPROC32_ID (0x1147)
      ...
      DisplayName: inlineFunction
      LinkageName: ?inlineFunction@@YAHH@Z
    }
    FrameProcSym {
      Kind: S_FRAMEPROC (0x1012)
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Param
    }
    DefRangeFramePointerRelSym {
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Var_1                              <-- Var_1 (*)
    }
    DefRangeFramePointerRelSym {
      Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
      ...
    }
    BlockSym {
      Kind: S_BLOCK32 (0x1103)                    <-- Lexical scope
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Var_2                              <-- Var_2(*)
    }
    DefRangeFramePointerRelSym {
      Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
      ...
    }
    ScopeEndSym {
      Kind: S_END (0x6)                           <-- End lexical scope
    }
    ProcEnd {
      Kind: S_PROC_ID_END (0x114F)
    }
  ]

(*) Var_1 and Var_2 at different lexical scopes.

This is the reduced output generated by llvm-readobj:

caller (testInlined)
-----------------------------------------------------------------


  Subsection [
      ...
    GlobalProcIdSym {
      Kind: S_GPROC32_ID (0x1147)
      ...
      DisplayName: testInlined
      LinkageName: ?testInlined@@YAHHH@Z
    }
    FrameProcSym {
      Kind: S_FRAMEPROC (0x1012)
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Param_1
    }
    DefRangeFramePointerRelSym {
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Param_2
    }
    DefRangeFramePointerRelSym {
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: A
    }
    DefRangeFramePointerRelSym {
      Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
      ...
    }
    InlineSiteSym {
      Kind: S_INLINESITE (0x114D)       <-- Lexical scope for inlined function
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Param
    }
    DefRangeFramePointerRelSym {
      Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Var_1                    <-- Var_1 (*)
    }
    DefRangeFramePointerRelSym {
      Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
      ...
    }
    LocalSym {
      Kind: S_LOCAL (0x113E)
      ...
      VarName: Var_2                    <-- Var_2 (*)
    }
    DefRangeFramePointerRelSym {
      Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
      ...
    }
    InlineSiteEnd {
      Kind: S_INLINESITE_END (0x114E)   <-- End lexical scope inlined function
    }
    ProcEnd {
      Kind: S_PROC_ID_END (0x114F)
    }
  ]
]

(*) Var_1 and Var_2 at the same lexical scope.

This is the ouput from llvm-diva (tool under development).


llvm-diva --print=scopes,symbols,types inlined-dwarf.o inlined-coff.o --attribute=level,format

Logical View:
[000]           {File} 'inlined-dwarf.o' -> ELF64-x86-64

[001]             {CompileUnit} 'inlined.cpp'
[002]     2         {Function} inlined 'inlineFunction' -> 'int'
[003]                 {Block} 
[004]     5             {Variable} 'Var_2' -> 'int'
[003]     2           {Parameter} 'Param' -> 'int'
[003]     3           {Variable} 'Var_1' -> 'int'
[002]     2         {Function} extern inlined 'inlineFunction' -> 'int'
[003]                 {Block} 
[004]     5             {Variable} 'Var_2' -> 'int'
[003]     2           {Parameter} 'Param' -> 'int'
[003]     3           {Variable} 'Var_1' -> 'int'
[002]    11         {Function} extern not_inlined 'testInlined' -> 'int'
[003]    13           {InlinedFunction} inlined 'inlineFunction' -> 'int'
[004]                   {Block} 
[005]     5               {Variable} 'Var_2' -> 'int'      <-- Var_2 (*)
[004]     2             {Parameter} 'Param' -> 'int'
[004]     3             {Variable} 'Var_1' -> 'int'        <-- Var_1 (*)
[003]    11           {Parameter} 'Param_1' -> 'int'
[003]    11           {Parameter} 'Param_2' -> 'int'
[003]    12           {Variable} 'A' -> 'int'

Logical View:
[000]           {File} 'inlined-coff.o' -> COFF-x86-64

[001]             {CompileUnit} 'inlined.cpp'
[002]               {Function} not_inlined 'inlineFunction' -> 'int'
[003]                 {Block} 
[004]                   {Variable} 'Var_2' -> 'int'
[003]                 {Parameter} 'Param' -> 'int'
[003]                 {Variable} 'Var_1' -> 'int'
[002]               {Function} not_inlined 'testInlined' -> 'int'
[003]                 {Variable} 'A' -> 'int'
[003]                 {Parameter} 'Param_1' -> 'int'
[003]                 {Parameter} 'Param_2' -> 'int'
[003]                 {InlinedFunction} inlined 'inlineFunction' -> 'int'
[004]                   {Parameter} 'Param' -> 'int'
[004]                   {Variable} 'Var_1' -> 'int'      <-- (**) Var_1
[004]                   {Variable} 'Var_2' -> 'int'      <-- (**) Var_2

The logical view for the DWARF debug info, shows 'Var_1' and 'Var_2'
at different lexical scopes:

(*) Var_1, scope [004]
(*) Var_2, scope [005]

The logical view for the COFF debug-info, shows 'Var_1' and 'Var_2'
at the same lexical scopes.

(**) Var_1, scope [004]
(**) Var_2, scope [004]

Would it be correct to say that the bug is: lexical scopes disappear from codeview after inlining?

There are some conditions under which lexical scopes may be ignored:
https://github.com/llvm/llvm-project/blob/master/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp#L2754

Perhaps this example hits one of those cases.

(In reply to Reid Kleckner from comment #5)

> There are some conditions under which lexical scopes may be ignored:
> https://github.com/llvm/llvm-project/blob/master/llvm/lib/CodeGen/AsmPrinter/
> CodeViewDebug.cpp#L2754

Thanks very much for the link.

For the given case,

https://github.com/llvm/llvm-project/blob/master/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp#L2769

const DILexicalBlock *DILB = dyn_cast<DILexicalBlock>(Scope.getScopeNode());

DILB is null.

From my understanding, the lexical blocks created due to the inlining
are not treated as standard ones and they have been ignored.

(In reply to Reid Kleckner from comment #5)
> Would it be correct to say that the bug is: lexical scopes disappear from
> codeview after inlining?

Yes. That would be a better description for the bug.

I am just starting to get familiar with the CodeView format and the
main question I have now is: Why the lexical scopes created during
inlining are treated in a different way as in DWARF?