gdb/testsuite/fortran: Add mixed language stack test

This commit adds a test that builds a mixed language stack, the stack
contains frames of Fortran, C, and C++.  The test prints the backtrace
and explores the stack printing arguments of different types in frames
of different languages.

The core of the test is repeated with GDB's language set to auto,
fortran, c, and c++ in turn to ensure that GDB is happy to print
frames and frame arguments when the language is set to a value that
doesn't match the frame language.

This test currently passes, and there are no known bugs in this area.
The aim of this commit is simply to increase test coverage, as I don't
believe this functionality is currently tested.

gdb/testsuite/ChangeLog:

	* gdb.fortran/mixed-lang-stack.c: New file.
	* gdb.fortran/mixed-lang-stack.cpp: New file.
	* gdb.fortran/mixed-lang-stack.exp: New file.
	* gdb.fortran/mixed-lang-stack.f90: New file.

1 files changed, 163 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.fortran/mixed-lang-stack.exp b/gdb/testsuite/gdb.fortran/mixed-lang-stack.exp
new file mode 100644
index 0000000..df0807e
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/mixed-lang-stack.exp
@@ -0,0 +1,163 @@
+# Copyright 2020 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 3 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, see <http://www.gnu.org/licenses/> .
+
+# This test covers some basic functionality for debugging mixed
+# Fortran, C, and C++ applications.  Features tested include examining
+# the backtrace, and printing frame arguments in frames of different
+# languages.
+#
+# One important aspect of this test is that we set the language in
+# turn to auto, fortran, c, and c++, and carry out the full test in
+# each case to ensure that trying to print objects or types from one
+# language, while GDB's language is set to another, doesn't crash GDB.
+
+if {[skip_fortran_tests]} { return -1 }
+
+standard_testfile mixed-lang-stack.c mixed-lang-stack.cpp mixed-lang-stack.f90
+
+if {[prepare_for_testing_full "failed to prepare" \
+	 [list ${binfile} {debug f90 additional_flags=-lstdc++} \
+	      $srcfile {debug} \
+	      $srcfile2 {debug c++} \
+	      $srcfile3 {debug f90}]]} {
+    return -1
+}
+
+# Runs the test program and examins the stack.  LANG is a string, the
+# value to pass to GDB's 'set language ...' command.
+proc run_tests { lang } {
+    with_test_prefix "lang=${lang}" {
+	global binfile hex
+
+	clean_restart ${binfile}
+
+	if ![runto_main] {
+	    untested "could not run to main"
+	    return -1
+	}
+
+	gdb_breakpoint "breakpt"
+	gdb_continue_to_breakpoint "breakpt"
+
+	if { $lang == "c" || $lang == "c++" } {
+	    gdb_test "set language c" \
+		"Warning: the current language does not match this frame."
+	} else {
+	    gdb_test_no_output "set language $lang"
+	}
+
+	# Check the backtrace.
+	set bt_stack [multi_line \
+			  "#0\\s+breakpt \\(\\) at \[^\r\n\]+" \
+			  "#1\\s+$hex in mixed_func_1h \\(\\) at \[^\r\n\]+" \
+			  "#2\\s+$hex in mixed_func_1g \\(obj=\\.\\.\\.\\) at \[^\r\n\]+" \
+			  "#3\\s+$hex in mixed_func_1f \\(\\) at \[^\r\n\]+" \
+			  "#4\\s+$hex in mixed_func_1e \\(\\) at \[^\r\n\]+" \
+			  "#5\\s+$hex in mixed_func_1d \\(\[^\r\n\]+\\) at \[^\r\n\]+" \
+			  "#6\\s+$hex in mixed_func_1c \\(\[^\r\n\]+\\) at \[^\r\n\]+" \
+			  "#7\\s+$hex in mixed_func_1b \\(\[^\r\n\]+\\) at \[^\r\n\]+" \
+			  "#8\\s+$hex in mixed_func_1a \\(\\) at \[^\r\n\]+" \
+			  "#9\\s+$hex in mixed_stack_main \\(\\) at \[^\r\n\]+" \
+			  "#10\\s+$hex in main \\(\[^\r\n\]+\\) at .*" ]
+	gdb_test "bt" $bt_stack
+
+	# Check the language for frame #0.
+	gdb_test "info frame" "source language fortran\..*" \
+	    "info frame in frame #0"
+
+	# Move up to the C++ frames and check the frame state, print a
+	# C++ object.
+	gdb_test "frame 2" "#2\\s+$hex in mixed_func_1g .*" \
+	    "select frame #2"
+	gdb_test "info frame" "source language c\\+\\+\..*" \
+	    "info frame in frame #2"
+	if { $lang == "fortran" } {
+	    set obj_pattern " = \\( base_one = \\( num1 = 1, num2 = 2, num3 = 3 \\), base_two = \\( string = 0x6184e0 'Something in C\\+\\+\\\\000', val = 3.5 \\), xxx = 9, yyy = 10.5 \\)"
+	} else {
+	    set obj_pattern " = \\{<base_one> = \\{num1 = 1, num2 = 2, num3 = 3\\}, <base_two> = \\{string = 0x6184e0 \"Something in C\\+\\+\", val = 3.5\\}, xxx = 9, yyy = 10.5\\}"
+	}
+	gdb_test "print obj" "${obj_pattern}"
+
+	# Move up the stack a way, and check frame and the frame
+	# arguments.
+	gdb_test "frame 5" "#5\\s+$hex in mixed_func_1d .*" \
+	    "select frame #5"
+	gdb_test "info frame" "source language fortran\..*" \
+	    "info frame in frame #5"
+
+	gdb_test "up" "#6\\s+$hex in mixed_func_1c .*" \
+	    "up to frame #6"
+	gdb_test "info frame" "source language c\..*" \
+	    "info frame in frame #6"
+
+	if { $lang == "fortran" } {
+	    set d_pattern "\\(4,5\\)"
+	    set f_pattern "$hex 'abcdef\\\\000'"
+	} else {
+	    set d_pattern "4 \\+ 5 \\* I"
+	    set f_pattern "$hex \"abcdef\""
+	}
+
+	set args_pattern [multi_line \
+			      "a = 1" \
+			      "b = 2" \
+			      "c = 3" \
+			      "d = ${d_pattern}" \
+			      "f = ${f_pattern}" \
+			      "g = $hex" ]
+
+	gdb_test "info args" $args_pattern \
+	    "info args in frame #6"
+	if { $lang == "fortran" } {
+	    set g_pattern " = \\( a = 1\\.5, b = 2\\.5 \\)"
+	} else {
+	    set g_pattern " = \\{a = 1\\.5, b = 2\\.5\\}"
+	}
+	gdb_test "print *g" "${g_pattern}" \
+	    "print object pointed to by g"
+
+	gdb_test "up" "#7\\s+$hex in mixed_func_1b .*" \
+	    "up to frame #7"
+	gdb_test "info frame" "source language fortran\..*" \
+	    "info frame in frame #7"
+
+	if { $lang == "c" || $lang == "c++" } {
+	    set d_pattern "4 \\+ 5 \\* I"
+	    set e_pattern "\"abcdef\""
+	    set g_pattern "\{a = 1.5, b = 2.5\}"
+	} else {
+	    set d_pattern "\\(4,5\\)"
+	    set e_pattern "'abcdef'"
+	    set g_pattern "\\( a = 1.5, b = 2.5 \\)"
+	}
+
+	set args_pattern [multi_line \
+			      "a = 1" \
+			      "b = 2" \
+			      "c = 3" \
+			      "d = ${d_pattern}" \
+			      "e = ${e_pattern}" \
+			      "g = ${g_pattern}" \
+			      "_e = 6" ]
+
+	gdb_test "info args" $args_pattern \
+	    "info args in frame #7"
+    }
+}
+
+run_tests "auto"
+run_tests "fortran"
+run_tests "c"
+run_tests "c++"