TO BE SQUASHED: suggestion for 3-arg version

Suggestion for the 3-arg version of
_ORTE_SETUP_DEBUGGER_FLAGS_TRY_CFLAGS().  Have to make it a bit
cleaner than the originally-proposed version to enable the nesting.
Also put in a final MSG_CHECKING/RESULT to indicate which flags were
ultimately chosen (it also gives a good place to grep for in the
configure output).

Signed-off-by: Jeff Squyres <[email protected]>

Author: jsquyres

config/orte_setup_debugger_flags.m4

@@ -10,7 +10,7 @@ dnl Copyright (c) 2004-2007 High Performance Computing Center Stuttgart,
 dnl                         University of Stuttgart.  All rights reserved.
 dnl Copyright (c) 2004-2005 The Regents of the University of California.
 dnl                         All rights reserved.
-dnl Copyright (c) 2006-2009 Cisco Systems, Inc.  All rights reserved.
+dnl Copyright (c) 2006-2019 Cisco Systems, Inc.  All rights reserved.
 dnl Copyright (c) 2006-2009 Sun Microsystems, Inc.  All rights reserved.
 dnl Copyright (c) 2006-2007 Los Alamos National Security, LLC.  All rights
 dnl                         reserved.
@@ -27,16 +27,23 @@ dnl
 dnl Check to see if specific CFLAGS work
 dnl $1: compiler flags to check
 dnl $2: Action if the flags work
+dnl $3: Action if the flags do not work
 AC_DEFUN([_ORTE_SETUP_DEBUGGER_FLAGS_TRY_CFLAGS],[
     OPAL_VAR_SCOPE_PUSH([ORTE_SETUP_DEBUGGER_FLAGS_CFLAGS_save])
+
     ORTE_SETUP_DEBUGGER_FLAGS_CFLAGS_save=$CFLAGS
     AC_MSG_CHECKING([if $1 compiler flag works])
     CFLAGS="$CFLAGS $1"
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],[int i = 3;])],
-        [$2; AC_MSG_RESULT([yes])],
-        [AC_MSG_RESULT([no])])
+        [ORTE_SETUP_DEBUGGER_FLAGS_HAPPY=yes],
+        [ORTE_SETUP_DEBUGGER_FLAGS_HAPPY=no])
+    AC_MSG_RESULT([$ORTE_SETUP_DEBUGGER_FLAGS_HAPPY])
     CFLAGS=$ORTE_SETUP_DEBUGGER_FLAGS_CFLAGS_save
+
     OPAL_VAR_SCOPE_POP
+
+    AS_IF([test $ORTE_SETUP_DEBUGGER_FLAGS_HAPPY = yes],
+          [$2], [$3])
 ])
 
 AC_DEFUN([ORTE_SETUP_DEBUGGER_FLAGS],[
@@ -75,25 +82,15 @@ AC_DEFUN([ORTE_SETUP_DEBUGGER_FLAGS],[
     # producing a stack when explicit unwind information is unavailable.
     # This is implied by -g, but we want to save space and don't need
     # full debug symbols.
-    OPAL_VAR_SCOPE_PUSH([foundFlags])
-    foundFlags=no
-    MPIR_UNWIND_CFLAGS=
-
-    # Test for GNU and Intel compiler flags
     _ORTE_SETUP_DEBUGGER_FLAGS_TRY_CFLAGS([-fasynchronous-unwind-tables],
-       [MPIR_UNWIND_CFLAGS=-fasynchronous-unwind-tables foundFlags=yes])
+        [MPIR_UNWIND_CFLAGS="-fasynchronous-unwind-tables"],
+        [_ORTE_SETUP_DEBUGGER_FLAGS_TRY_CFLAGS([-Meh_frame -Mframe],
+            [MPIR_UNWIND_CFLAGS="-Meh_frame -Mframe"],
+            [MPIR_UNWIND_CFLAGS=-g])
+        ])
 
-    # Test for PGI compiler flags
-    if test $foundFlags = no; then
-        _ORTE_SETUP_DEBUGGER_FLAGS_TRY_CFLAGS([-Meh_frame -Mframe],
-            [MPIR_UNWIND_CFLAGS="-Meh_frame -Mframe" foundFlags=yes])
-    fi
+    AC_MSG_CHECKING([for final compiler unwind flags])
+    AC_MSG_RESULT([$MPIR_UNWIND_CFLAGS])
 
-    # Finally fall back to -g if neither of the above were available
-    if test $foundFlags = no; then
-        _ORTE_SETUP_DEBUGGER_FLAGS_TRY_CFLAGS([-g],
-            [MPIR_UNWIND_CFLAGS=-g])
-    fi
     AC_SUBST(MPIR_UNWIND_CFLAGS)
-    OPAL_VAR_SCOPE_POP
 ])