From: =?utf-8?b?SMOpY3RvciBPcsOzbiBNYXJ0w61uZXo=?= <zumbi@debian.org>
Date: Wed, 20 Feb 2019 13:25:36 +0100
Subject: gdb-fortran-main

Daniel,

Although the proper way of adding case insensitivity to symbol lookup is 
still under discussion, I think it might be desirable to set the main 
function of Fortran programs to "MAIN__" first.  Because it can at least 
let GDB recognize that the language is Fortran after loading a Fortran 
executable only.  What is your idea on this?  Please comments.  TIA!

Here is the patch to set the main function in Fortran programs to 
"MAIN__".  And followed is a patch to verify this.  Tested with g77 and 
gfortran on x86, and g77 on ppc64.  With the first patch, it reported 
PASS; without, report FAIL.  No regression is found in gdb.fortran 
testcases.  

P.S: if there is a symbol named "MAIN__" in sources of other languages, it 
might disturb the debugging.  But I am not sure how much it is.
---
 gdb/symtab.c                       |  9 +++++++--
 gdb/testsuite/gdb.fortran/lang.exp | 40 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 gdb/testsuite/gdb.fortran/lang.exp

Index: gdb/gdb/symtab.c
===================================================================
--- gdb.orig/gdb/symtab.c
+++ gdb/gdb/symtab.c
@@ -6156,7 +6156,13 @@ find_main_name (void)
       return;
     }
 
-  set_main_name ("main", language_unknown);
+/* Fallback to "MAIN__" (g77 and gfortran) if we can find it in the
+ * minimal symtab, to "main" otherwise.  */
+  struct bound_minimal_symbol msym = lookup_minimal_symbol ("MAIN__", NULL, NULL);
+  if (msym.minsym)
+    set_main_name ("MAIN__", language_fortran);
+  else
+    set_main_name ("main", language_unknown);
 }
 
 /* See symtab.h.  */
Index: gdb/gdb/testsuite/gdb.fortran/lang.exp
===================================================================
--- /dev/null
+++ gdb/gdb/testsuite/gdb.fortran/lang.exp
@@ -0,0 +1,40 @@
+# Copyright 2005 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+# This file was written by Wu Zhou. (woodzltc@cn.ibm.com)
+
+# This file is part of the gdb testsuite.  It is intended to test that gdb
+# could recognize the Fortran language after loading the binary
+
+if $tracelevel then {
+	strace $tracelevel
+}
+
+set testfile "array-element"
+set srcfile ${srcdir}/${subdir}/${testfile}.f
+set binfile ${objdir}/${subdir}/${testfile}
+
+if  { [gdb_compile "${srcfile}" "${binfile}" executable {debug f77}] != "" } {
+    untested "Couldn't compile ${srcfile}"
+    return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+gdb_test "show language" ".*currently fortran.*" "show language(fortran)"