[llvm-bugs] [Bug 44695] New: [DebugInfo] Static variables declared inside functions always have the function scope

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=44695

            Bug ID: 44695
           Summary: [DebugInfo] Static variables declared inside functions
                    always have the function scope
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: DebugInfo
          Assignee: unassignedbugs at nondot.org
          Reporter: ch.bessonova at gmail.com
                CC: aprantl at apple.com, jdevlieghere at apple.com,
                    keith.walker at arm.com, llvm-bugs at lists.llvm.org,
                    paul_robinson at playstation.sony.com

If a static variable is defined inside of some bracketed block in a function,
clang/llvm will handle it as it has the function scope, not the corresponded
bracketed block scope.
Conside the following example:

 1  int foo() { return 42; };
 2  int main() {
 3    int a = foo();
 4    switch(a) {
 5    case 1: {
 6      static const int a = 1;
 7      return a;
 8    }
 9    case 2: {
10      static const int a = 2;
11      return a;
12    }
13    }
14  }

Here are 3 'a' variables, all of them have function scope according to the
dwarfdump:

0x0000002a:   DW_TAG_subprogram
                DW_AT_low_pc  (0x0000000000401120)
                DW_AT_high_pc (0x000000000040117a)
                DW_AT_frame_base  (DW_OP_reg6 RBP)
                DW_AT_name  ("main")
                DW_AT_decl_file ("temp.cpp")
                DW_AT_decl_line (3) 
                DW_AT_type  (0x00000081 "int")
                DW_AT_external  (true)

0x00000043:     DW_TAG_variable
                  DW_AT_name  ("a")
                  DW_AT_type  (0x0000007c "const int")
                  DW_AT_decl_file ("temp.cpp")
                  DW_AT_decl_line (7) 
                  DW_AT_location  (DW_OP_addr 0x402004)

0x00000058:     DW_TAG_variable
                  DW_AT_name  ("a")
                  DW_AT_type  (0x0000007c "const int")
                  DW_AT_decl_file ("temp.cpp")
                  DW_AT_decl_line (11)
                  DW_AT_location  (DW_OP_addr 0x402008)

0x0000006d:     DW_TAG_variable
                  DW_AT_location  (DW_OP_fbreg -8) 
                  DW_AT_name  ("a")
                  DW_AT_decl_file ("temp.cpp")
                  DW_AT_decl_line (4) 
                  DW_AT_type  (0x00000081 "int")


This confuses debuggers: gdb will print 1 for 'a' even on line 4.

Note: gcc-9.2 generates DW_TAG_lexical_block's for the bracketed blocks and
puts static 'a's there, so gdb prints 42 for 'a' on line 4 as expected.

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