gdb: remove check for minimal symbols in 'start_command'

GDB aborts the 'start' command if the minimal symbols cannot be
resolved.  On Windows, GDB reads the minimal symbols from the COFF
header of the PE file.  The symbol table is deprecated and the
number of symbols in the COFF header may be zero:

  https://learn.microsoft.com/en-us/windows/win32/debug/pe-format

This is reproducible with clang version 18.1.8 on Windows:

  clang++ -g -O0 -gdwarf -fuse-ld=lld test.cpp -o test_clang

The COFF file header shows:

  FILE HEADER VALUES
        8664 machine (x64)
           E number of sections
    66E889EC time date stamp Mon Sep 16 21:41:32 2024
       FB400 file pointer to symbol table
           0 number of symbols
          F0 size of optional header
          22 characteristics

GDB is not able to read the minimal symbols; the `start' command fails
with an error:

  (gdb) start
  No symbol table loaded.  Use the "file" command.

Manually inserting a breakpoint in main works fine:

  (gdb) tbreak main
  Temporary breakpoint 1 at 0x14000100c: file test.cpp, line 6.
  (gdb) run
  Starting program: C:\test-clang

  Temporary breakpoint 1, main () at test.cpp:6
  6         std::cout << "Hello World.\n";

Remove the check entirely; a 'NOT_FOUND_ERROR' is thrown if 'main'
cannot be resolved.  The error is consumed in 'create_breakpoint ()'
and an error message is displayed to the user.

Approved-by: Kevin Buettner <kevinb@redhat.com>
Reviewed-By: Guinevere Larsen <guinevere@redhat.com>

diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index b6b21a46b3d457ca45973bc1ddf0738804b52bcb..00703e44b7b5e7e070eb2080f96323d68f163609 100644 (file)
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -517,12 +517,6 @@ run_command (const char *args, int from_tty)
 static void
 start_command (const char *args, int from_tty)
 {
-  /* Some languages such as Ada need to search inside the program
-     minimal symbols for the location where to put the temporary
-     breakpoint before starting.  */
-  if (!have_minimal_symbols (current_program_space))
-    error (_("No symbol table loaded.  Use the \"file\" command."));
-
   /* Run the program until reaching the main procedure...  */
   run_command_1 (args, from_tty, RUN_STOP_AT_MAIN);
 }