gdb: Introduce 'print max-depth' feature

Introduce a new print setting max-depth which can be set with 'set
print max-depth DEPTH'.  The default value of DEPTH is 20, but this
can also be set to unlimited.

When GDB is printing a value containing nested structures GDB will
stop descending at depth DEPTH.  Here is a small example:

    typedef struct s1 { int a; } s1;
    typedef struct s2 { s1 b; } s2;
    typedef struct s3 { s2 c; } s3;
    typedef struct s4 { s3 d; } s4;

    s4 var = { { { { 3 } } } };

The following table shows how various depth settings affect printing
of 'var':

    | Depth Setting | Result of 'p var'              |
    |---------------+--------------------------------|
    |     Unlimited | $1 = {d = {c = {b = {a = 3}}}} |
    |             4 | $1 = {d = {c = {b = {a = 3}}}} |
    |             3 | $1 = {d = {c = {b = {...}}}}   |
    |             2 | $1 = {d = {c = {...}}}         |
    |             1 | $1 = {d = {...}}               |
    |             0 | $1 = {...}                     |

Only structures, unions, and arrays are replaced in this way, scalars
and strings are not replaced.

The replacement is counted from the level at which you print, not from
the top level of the structure.  So, consider the above example and
this GDB session:

    (gdb) set print max-depth 2
    (gdb) p var
    $1 = {d = {c = {...}}}
    (gdb) p var.d
    $2 = {c = {b = {...}}}
    (gdb) p var.d.c
    $3 = {b = {a = 3}}

Setting the max-depth to 2 doesn't prevent the user from exploring
deeper into 'var' by asking for specific sub-fields to be printed.

The motivation behind this feature is to try and give the user more
control over how much is printed when examining large, complex data
structures.

The default max-depth of 20 means that there is a change in GDB's
default behaviour.  Someone printing a data structure with 20 levels
of nesting will now see '{...}' instead of their data, they would need
to adjust the max depth, or call print again naming a specific field
in order to dig deeper into their data structure.  If this is
considered a problem then we could increase the default, or even make
the default unlimited.

This commit relies on the previous commit, which added a new field to
the language structure, this new field was a string that contained the
pattern that should be used when a structure/union/array is replaced
in the output, this allows languages to use a syntax that is more
appropriate, mostly this will be selecting the correct types of
bracket '(...)' or '{...}', both of which are currently in use.

This commit should have no impact on MI output, expressions are
printed through the MI using -var-create and then -var-list-children.
As each use of -var-list-children only ever displays a single level of
an expression then the max-depth setting will have no impact.

This commit also adds the max-depth mechanism to the scripting
language pretty printers following basically the same rules as for the
built in value printing.

One quirk is that when printing a value using the display hint 'map',
if the keys of the map are structs then GDB will hide the keys one
depth level after it hides the values, this ensures that GDB produces
output like this:

  $1 = map_object = {[{key1}] = {...}, [{key2}] = {...}}

Instead of this less helpful output:

  $1 = map_object = {[{...}] = {...}, [{...}] = {...}}

This is covered by the new tests in gdb.python/py-nested-maps.exp.

gdb/ChangeLog:

	* cp-valprint.c (cp_print_value_fields): Allow an additional level
	of depth when printing anonymous structs or unions.
	* guile/scm-pretty-print.c (gdbscm_apply_val_pretty_printer):
	Don't print either the top-level value, or the children if the
	max-depth is exceeded.
	(ppscm_print_children): When printing the key of a map, allow one
	extra level of depth.
	* python/py-prettyprint.c (gdbpy_apply_val_pretty_printer): Don't
	print either the top-level value, or the children if the max-depth
	is exceeded.
	(print_children): When printing the key of a map, allow one extra
	level of depth.
	* python/py-value.c (valpy_format_string): Add max_depth keyword.
	* valprint.c: (PRINT_MAX_DEPTH_DEFAULT): Define.
	(user_print_options): Initialise max_depth field.
	(val_print_scalar_or_string_type_p): New function.
	(val_print): Check to see if the max depth has been reached.
	(val_print_check_max_depth): Define new function.
	(show_print_max_depth): New function.
	(_initialize_valprint): Add 'print max-depth' option.
	* valprint.h (struct value_print_options) <max_depth>: New field.
	(val_print_check_max_depth): Declare new function.
	* NEWS: Document new feature.

gdb/doc/ChangeLog:

	* gdb.texinfo (Print Settings): Document 'print max-depth'.
	* guile.texi (Guile Pretty Printing API): Document that 'print
	max-depth' can effect the display of a values children.
	* python.texi (Pretty Printing API): Likewise.
	(Values From Inferior): Document max_depth keyword.

gdb/testsuite/ChangeLog:

	* gdb.base/max-depth.c: New file.
	* gdb.base/max-depth.exp: New file.
	* gdb.python/py-nested-maps.c: New file.
	* gdb.python/py-nested-maps.exp: New file.
	* gdb.python/py-nested-maps.py: New file.
	* gdb.python/py-format-string.exp (test_max_depth): New proc.
	(test_all_common): Call test_max_depth.
	* gdb.fortran/max-depth.exp: New file.
	* gdb.fortran/max-depth.f90: New file.
	* gdb.go/max-depth.exp: New file.
	* gdb.go/max-depth.go: New file.
	* gdb.modula2/max-depth.exp: New file.
	* gdb.modula2/max-depth.c: New file.
	* lib/gdb.exp (get_print_expr_at_depths): New proc.

14 files changed, 1215 insertions, 0 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index b6c3618..6d9ac5a 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,21 @@
+2019-04-29  Andrew Burgess  <andrew.burgess@embecosm.com>
+	    Richard Bunt  <richard.bunt@arm.com>
+
+	* gdb.base/max-depth.c: New file.
+	* gdb.base/max-depth.exp: New file.
+	* gdb.python/py-nested-maps.c: New file.
+	* gdb.python/py-nested-maps.exp: New file.
+	* gdb.python/py-nested-maps.py: New file.
+	* gdb.python/py-format-string.exp (test_max_depth): New proc.
+	(test_all_common): Call test_max_depth.
+	* gdb.fortran/max-depth.exp: New file.
+	* gdb.fortran/max-depth.f90: New file.
+	* gdb.go/max-depth.exp: New file.
+	* gdb.go/max-depth.go: New file.
+	* gdb.modula2/max-depth.exp: New file.
+	* gdb.modula2/max-depth.c: New file.
+	* lib/gdb.exp (get_print_expr_at_depths): New proc.
+
 2019-04-29  Tom de Vries  <tdevries@suse.de>
 
 	* lib/opencl.exp (skip_opencl_tests): Add missing "with" in regexp.
diff --git a/gdb/testsuite/gdb.base/max-depth.c b/gdb/testsuite/gdb.base/max-depth.c
new file mode 100644
index 0000000..3c57249
--- /dev/null
+++ b/gdb/testsuite/gdb.base/max-depth.c
@@ -0,0 +1,232 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2019 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/>.  */
+
+struct s1
+{
+  int x;
+  int y;
+} s1;
+
+struct s2
+{
+  int x;
+  int y;
+  struct
+  {
+    int z;
+    int a;
+  };
+} s2;
+
+struct s3
+{
+  int x;
+  int y;
+  struct
+  {
+    int z;
+    int a;
+    struct
+    {
+      int b;
+      int c;
+    };
+  };
+} s3;
+
+struct s4
+{
+  int x;
+  int y;
+  struct
+  {
+    int x;
+    int y;
+    struct
+    {
+      int x;
+      int y;
+    } l2;
+  } l1;
+} s4;
+
+struct s5
+{
+  union
+  {
+    int raw[3];
+    struct
+    {
+      int x;
+      int y;
+      int z;
+    };
+  };
+} s5;
+
+typedef struct
+{
+  union
+  {
+    int raw[3];
+    struct
+    {
+      int x;
+      int y;
+      int z;
+    };
+  };
+} s6_t;
+
+s6_t s6;
+
+struct s7
+{
+  struct
+  {
+    int x;
+    int y;
+  };
+  struct
+  {
+    int z;
+    int a;
+  };
+  struct
+  {
+    int b;
+    int c;
+  };
+} s7;
+
+struct s8
+{
+  int x;
+  int y;
+  struct
+  {
+    int z;
+    int a;
+    struct
+    {
+      int b;
+      int c;
+    };
+  } d1;
+} s8;
+
+struct s9
+{
+  int x;
+  int y;
+  struct
+  {
+    int k;
+    int j;
+    struct
+    {
+      int z;
+      int a;
+      struct
+      {
+        int b;
+        int c;
+      };
+    } d1;
+  };
+  struct
+  {
+    int z;
+    int a;
+    struct
+    {
+      int b;
+      int c;
+    };
+  } d2;
+} s9;
+
+struct s10
+{
+  int x[10];
+  int y;
+  struct
+  {
+    int k[10];
+    int j;
+    struct
+    {
+      int z;
+      int a;
+      struct
+      {
+        int b[10];
+        int c;
+      };
+    } d1;
+  };
+  struct
+  {
+    int z;
+    int a;
+    struct
+    {
+      int b[10];
+      int c;
+    };
+  } d2;
+} s10;
+
+struct s11
+{
+  int x;
+  char s[10];
+  struct
+  {
+    int z;
+    int a;
+  };
+} s11;
+
+/* The following are C++ inheritance testing.  */
+#ifdef __cplusplus
+
+/* This is non-virtual inheritance.  */
+struct C1 { int c1 = 1; } c1;
+struct C2 { int c2 = 2; } c2;
+struct C3 : C2 { int c3 = 3; } c3;
+struct C4 { int c4 = 4; } c4;
+struct C5 : C4 { int c5 = 5; } c5;
+struct C6 : C5 { int c6 = 6; } c6;
+struct C7 : C1, C3, C6 { int c7 = 7; } c7;
+
+/* This is virtual inheritance.  */
+struct V1 { int v1 = 1; } v1;
+struct V2 : virtual V1 { int v2 = 2; } v2;
+struct V3 : virtual V1 { int v3 = 3; } v3;
+struct V4 : virtual V2 { int v4 = 4; } v4;
+struct V5 : virtual V2 { int v5 = 1; } v5;
+struct V6 : virtual V2, virtual V3 { int v6 = 1; } v6;
+struct V7 : virtual V4, virtual V5, virtual V6 { int v7 = 1; } v7;
+
+#endif /* __cplusplus */
+
+int
+main ()
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/max-depth.exp b/gdb/testsuite/gdb.base/max-depth.exp
new file mode 100644
index 0000000..b3b7876
--- /dev/null
+++ b/gdb/testsuite/gdb.base/max-depth.exp
@@ -0,0 +1,165 @@
+# Copyright 2019 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/>.
+
+# Tests GDB's handling of 'set print max-depth'.
+
+# Only test C++ if we are able.  Always use C.
+if { [skip_cplus_tests] || [get_compiler_info "c++"] } {
+    set lang {c}
+} else {
+    set lang {c c++}
+}
+
+foreach l $lang {
+    set dir "$l"
+    remote_exec host "rm -rf [standard_output_file ${dir}]"
+    remote_exec host "mkdir -p [standard_output_file ${dir}]"
+}
+
+proc compile_and_run_tests { lang } {
+    global testfile
+    global srcfile
+    global binfile
+    global hex
+
+    standard_testfile .c
+
+    # Create the additional flags.
+    set flags "debug"
+    lappend flags $lang
+
+    set dir "$lang"
+    set binfile [standard_output_file ${dir}/${testfile}]
+    if { [prepare_for_testing "failed to prepare" "${binfile}" "${srcfile}" "${flags}"] } {
+	return 0
+    }
+
+    # Advance to main.
+    if { ![runto_main] } then {
+	fail "can't run to main"
+	return 0
+    }
+
+    # The max-depth setting has no effect as the anonymous scopes are
+    # ignored and the members are aggregated into the parent scope.
+    gdb_print_expr_at_depths "s1" {"{...}" \
+				       "{x = 0, y = 0}"\
+				       "{x = 0, y = 0}"}
+
+    gdb_print_expr_at_depths "s2" {"{...}" \
+				       "{x = 0, y = 0, {z = 0, a = 0}}" \
+				       "{x = 0, y = 0, {z = 0, a = 0}}"}
+
+    gdb_print_expr_at_depths "s3" {"{...}" \
+				       "{x = 0, y = 0, {z = 0, a = 0, {b = 0, c = 0}}}" \
+				       "{x = 0, y = 0, {z = 0, a = 0, {b = 0, c = 0}}}" \
+				       "{x = 0, y = 0, {z = 0, a = 0, {b = 0, c = 0}}}"}
+
+    # Increasing max-depth unfurls more of the object.
+    gdb_print_expr_at_depths "s4" {"{...}" \
+				       "{x = 0, y = 0, l1 = {...}}" \
+				       "{x = 0, y = 0, l1 = {x = 0, y = 0, l2 = {...}}}" \
+				       "{x = 0, y = 0, l1 = {x = 0, y = 0, l2 = {x = 0, y = 0}}}"}
+
+    # Check handling of unions, in this case 'raw' is printed instead of
+    # just {...} as this is not useful.
+    gdb_print_expr_at_depths "s5" {"{...}" \
+				       "{{raw = {...}, {x = 0, y = 0, z = 0}}}" \
+				       "{{raw = \\{0, 0, 0\\}, {x = 0, y = 0, z = 0}}}"}
+
+    # Check handling of typedefs.
+    gdb_print_expr_at_depths "s6" {"{...}" \
+				       "{{raw = {...}, {x = 0, y = 0, z = 0}}}" \
+				       "{{raw = \\{0, 0, 0\\}, {x = 0, y = 0, z = 0}}}"}
+
+    # Multiple anonymous structures in parallel.
+    gdb_print_expr_at_depths "s7" {"{...}" \
+				       "{{x = 0, y = 0}, {z = 0, a = 0}, {b = 0, c = 0}}" \
+				       "{{x = 0, y = 0}, {z = 0, a = 0}, {b = 0, c = 0}}"}
+
+    # Flip flop between named and anonymous.  Expected to unfurl to the
+    # first non-anonymous type.
+    gdb_print_expr_at_depths "s8" {"{...}" \
+				       "{x = 0, y = 0, d1 = {...}}" \
+				       "{x = 0, y = 0, d1 = {z = 0, a = 0, {b = 0, c = 0}}}"}
+
+    # Imbalanced tree, this will unfurl one size more than the other as
+    # one side has more anonymous levels.
+    gdb_print_expr_at_depths "s9" {"{...}" \
+				       "{x = 0, y = 0, {k = 0, j = 0, d1 = {...}}, d2 = {...}}" \
+				       "{x = 0, y = 0, {k = 0, j = 0, d1 = {z = 0, a = 0, {b = 0, c = 0}}}, d2 = {z = 0, a = 0, {b = 0, c = 0}}}"}
+
+    # Arrays are treated as an extra level, while scalars are not.
+    gdb_print_expr_at_depths "s10" {"{...}" \
+					"{x = {...}, y = 0, {k = {...}, j = 0, d1 = {...}}, d2 = {...}}" \
+					"{x = \\{0, 0, 0, 0, 0, 0, 0, 0, 0, 0\\}, y = 0, {k = \\{0, 0, 0, 0, 0, 0, 0, 0, 0, 0\\}, j = 0, d1 = {z = 0, a = 0, {b = {...}, c = 0}}}, d2 = {z = 0, a = 0, {b = {...}, c = 0}}}" \
+					"{x = \\{0, 0, 0, 0, 0, 0, 0, 0, 0, 0\\}, y = 0, {k = \\{0, 0, 0, 0, 0, 0, 0, 0, 0, 0\\}, j = 0, d1 = {z = 0, a = 0, {b = \\{0, 0, 0, 0, 0, 0, 0, 0, 0, 0\\}, c = 0}}}, d2 = {z = 0, a = 0, {b = \\{0, 0, 0, 0, 0, 0, 0, 0, 0, 0\\}, c = 0}}}"}
+
+    # Strings are treated as scalars.
+    gdb_print_expr_at_depths "s11" {"{...}" \
+					"{x = 0, s = \"\\\\000\\\\000\\\\000\\\\000\\\\000\\\\000\\\\000\\\\000\\\\000\", {z = 0, a = 0}}"}
+
+
+    if { $lang == "c++" } {
+	gdb_print_expr_at_depths "c1" {"{...}" \
+					   "{c1 = 1}" }
+	gdb_print_expr_at_depths "c2" { "{...}" "{c2 = 2}" }
+	gdb_print_expr_at_depths "c3" { "{...}" \
+					    "{<C2> = {...}, c3 = 3}" \
+					    "{<C2> = {c2 = 2}, c3 = 3}" }
+	gdb_print_expr_at_depths "c4" { "{...}" "{c4 = 4}" }
+	gdb_print_expr_at_depths "c5" { "{...}" \
+					    "{<C4> = {...}, c5 = 5}" \
+					    "{<C4> = {c4 = 4}, c5 = 5}" }
+	gdb_print_expr_at_depths "c6" { "{...}" \
+					    "{<C5> = {...}, c6 = 6}" \
+					    "{<C5> = {<C4> = {...}, c5 = 5}, c6 = 6}" \
+					    "{<C5> = {<C4> = {c4 = 4}, c5 = 5}, c6 = 6}" }
+	gdb_print_expr_at_depths "c7" { "{...}" \
+					    "{<C1> = {...}, <C3> = {...}, <C6> = {...}, c7 = 7}" \
+					    "{<C1> = {c1 = 1}, <C3> = {<C2> = {...}, c3 = 3}, <C6> = {<C5> = {...}, c6 = 6}, c7 = 7}" \
+					    "{<C1> = {c1 = 1}, <C3> = {<C2> = {c2 = 2}, c3 = 3}, <C6> = {<C5> = {<C4> = {...}, c5 = 5}, c6 = 6}, c7 = 7}" \
+					    "{<C1> = {c1 = 1}, <C3> = {<C2> = {c2 = 2}, c3 = 3}, <C6> = {<C5> = {<C4> = {c4 = 4}, c5 = 5}, c6 = 6}, c7 = 7}" }
+
+	gdb_print_expr_at_depths "v1" [list "{...}" "{v1 = 1}" ]
+	gdb_print_expr_at_depths "v2" [list "{...}" \
+					    "{<V1> = {...}, _vptr.V2 = $hex <VTT for V2>, v2 = 2}" \
+					    "{<V1> = {v1 = 1}, _vptr.V2 = $hex <VTT for V2>, v2 = 2}" ]
+	gdb_print_expr_at_depths "v3" [list "{...}" \
+					    "{<V1> = {...}, _vptr.V3 = $hex <VTT for V3>, v3 = 3}" \
+					    "{<V1> = {v1 = 1}, _vptr.V3 = $hex <VTT for V3>, v3 = 3}" ]
+	gdb_print_expr_at_depths "v4" [list "{...}" \
+					    "{<V2> = {...}, _vptr.V4 = $hex <vtable for V4\[^>\]+>, v4 = 4}" \
+					    "{<V2> = {<V1> = {...}, _vptr.V2 = $hex <VTT for V4>, v2 = 2}, _vptr.V4 = $hex <vtable for V4\[^>\]+>, v4 = 4}" \
+					    "{<V2> = {<V1> = {v1 = 1}, _vptr.V2 = $hex <VTT for V4>, v2 = 2}, _vptr.V4 = $hex <vtable for V4\[^>\]+>, v4 = 4}" ]
+	gdb_print_expr_at_depths "v5" [list "{...}" \
+					    "{<V2> = {...}, _vptr.V5 = $hex <vtable for V5\[^>\]+>, v5 = 1}" \
+					    "{<V2> = {<V1> = {...}, _vptr.V2 = $hex <VTT for V5>, v2 = 2}, _vptr.V5 = $hex <vtable for V5\[^>\]+>, v5 = 1}" \
+					    "{<V2> = {<V1> = {v1 = 1}, _vptr.V2 = $hex <VTT for V5>, v2 = 2}, _vptr.V5 = $hex <vtable for V5\[^>\]+>, v5 = 1}" ]
+	gdb_print_expr_at_depths "v6" [list "{...}" \
+					    "{<V2> = {...}, <V3> = {...}, _vptr.V6 = $hex <vtable for V6\[^>\]+>, v6 = 1}" \
+					    "{<V2> = {<V1> = {...}, _vptr.V2 = $hex <vtable for V6\[^>\]+>, v2 = 2}, <V3> = {_vptr.V3 = $hex <VTT for V6>, v3 = 3}, _vptr.V6 = $hex <vtable for V6\[^>\]+>, v6 = 1}" \
+					    "{<V2> = {<V1> = {v1 = 1}, _vptr.V2 = $hex <vtable for V6\[^>\]+>, v2 = 2}, <V3> = {_vptr.V3 = $hex <VTT for V6>, v3 = 3}, _vptr.V6 = $hex <vtable for V6\[^>\]+>, v6 = 1}" ]
+	gdb_print_expr_at_depths "v7" [list "{...}" \
+					    "{<V4> = {...}, <V5> = {...}, <V6> = {...}, _vptr.V7 = $hex <vtable for V7\[^>\]+>, v7 = 1}" \
+					    "{<V4> = {<V2> = {...}, _vptr.V4 = $hex <vtable for V7\[^>\]+>, v4 = 4}, <V5> = {_vptr.V5 = $hex <vtable for V7\[^>\]+>, v5 = 1}, <V6> = {<V3> = {...}, _vptr.V6 = $hex <vtable for V7\[^>\]+>, v6 = 1}, _vptr.V7 = $hex <vtable for V7\[^>\]+>, v7 = 1}" \
+					    "{<V4> = {<V2> = {<V1> = {...}, _vptr.V2 = $hex <vtable for V7\[^>\]+>, v2 = 2}, _vptr.V4 = $hex <vtable for V7\[^>\]+>, v4 = 4}, <V5> = {_vptr.V5 = $hex <vtable for V7\[^>\]+>, v5 = 1}, <V6> = {<V3> = {_vptr.V3 = $hex <VTT for V7>, v3 = 3}, _vptr.V6 = $hex <vtable for V7\[^>\]+>, v6 = 1}, _vptr.V7 = $hex <vtable for V7\[^>\]+>, v7 = 1}" \
+					    "{<V4> = {<V2> = {<V1> = {v1 = 1}, _vptr.V2 = $hex <vtable for V7\[^>\]+>, v2 = 2}, _vptr.V4 = $hex <vtable for V7\[^>\]+>, v4 = 4}, <V5> = {_vptr.V5 = $hex <vtable for V7\[^>\]+>, v5 = 1}, <V6> = {<V3> = {_vptr.V3 = $hex <VTT for V7>, v3 = 3}, _vptr.V6 = $hex <vtable for V7\[^>\]+>, v6 = 1}, _vptr.V7 = $hex <vtable for V7\[^>\]+>, v7 = 1}" ]
+    }
+}
+
+foreach_with_prefix l $lang {
+    compile_and_run_tests $l
+}
diff --git a/gdb/testsuite/gdb.fortran/max-depth.exp b/gdb/testsuite/gdb.fortran/max-depth.exp
new file mode 100644
index 0000000..8b0bb80
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/max-depth.exp
@@ -0,0 +1,41 @@
+# Copyright 2019 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 file tests GDB's handling of 'set print max-depth' for nested
+# fortran types.
+
+load_lib "fortran.exp"
+
+if { [skip_fortran_tests] } { continue }
+
+standard_testfile .f90
+
+if { [prepare_for_testing "failed to prepare" $testfile $srcfile {debug f90}] } {
+    return -1
+}
+
+if { ![runto MAIN__] } {
+    perror "Could not run to breakpoint `MAIN__'."
+    continue
+}
+
+gdb_breakpoint [gdb_get_line_number "stop-here"]
+gdb_continue_to_breakpoint "stop-here" ".*stop-here.*"
+
+gdb_print_expr_at_depths "var" {"\\(\\.\\.\\.\\)" \
+				    "\\( d = \\(\\.\\.\\.\\) \\)" \
+				    "\\( d = \\( string = 'abcde', c = \\(\\.\\.\\.\\) \\) \\)" \
+				    "\\( d = \\( string = 'abcde', c = \\( b = \\(\\.\\.\\.\\), array = \\(\\.\\.\\.\\) \\) \\) \\)" \
+				    "\\( d = \\( string = 'abcde', c = \\( b = \\( a = 1 \\), array = \\(0, 0, 0, 0, 0\\) \\) \\) \\)" }
diff --git a/gdb/testsuite/gdb.fortran/max-depth.f90 b/gdb/testsuite/gdb.fortran/max-depth.f90
new file mode 100644
index 0000000..9b6f90c
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/max-depth.f90
@@ -0,0 +1,42 @@
+! Copyright 2019 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, see <http://www.gnu.org/licenses/>.
+
+program max_depth_test
+  type :: s1
+     integer :: a
+  end type s1
+
+  type :: s2
+     type (s1) :: b
+     integer :: array (5)
+  end type s2
+
+  type :: s3
+     character(5) :: string
+     type (s2) :: c
+  end type s3
+
+  type :: s4
+     type (s3) :: d
+  end type s4
+
+  logical :: l
+  type (s4) :: var
+
+  var%d%c%b%a = 1
+  var%d%c%array = 0
+  var%d%string = "abcde"
+  l = .FALSE.					! stop-here
+end program max_depth_test
diff --git a/gdb/testsuite/gdb.go/max-depth.exp b/gdb/testsuite/gdb.go/max-depth.exp
new file mode 100644
index 0000000..0f8ba9a
--- /dev/null
+++ b/gdb/testsuite/gdb.go/max-depth.exp
@@ -0,0 +1,40 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2019 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/>.
+
+# Test the use of 'set prinnt max-depth' when printing go structures.
+
+load_lib "go.exp"
+
+if { [skip_go_tests] } { continue }
+
+standard_testfile .go
+
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} {debug go}] } {
+    return -1
+}
+
+if { [go_runto_main] < 0 } {
+    untested "could not run to main"
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Break here"]
+gdb_continue_to_breakpoint "run to breakpoint" ".*Break here.*"
+
+gdb_print_expr_at_depths "s1" [list "{...}" \
+				    "{m_struct = {...}, m_string = $hex \"hello world\"}" \
+				    "{m_struct = {m_a = 3, m_b = 7}, m_string = $hex \"hello world\"}"]
diff --git a/gdb/testsuite/gdb.go/max-depth.go b/gdb/testsuite/gdb.go/max-depth.go
new file mode 100644
index 0000000..6dbfc22
--- /dev/null
+++ b/gdb/testsuite/gdb.go/max-depth.go
@@ -0,0 +1,41 @@
+// Copyright 2019 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/>.
+
+package main
+
+import "fmt"
+
+type S1 struct {
+     m_a int
+     m_b int
+}
+
+type S2 struct {
+     m_struct S1
+     m_string string
+}
+
+func main () {
+  var s1 S2
+  var i int
+
+  s1.m_string = "hello world"
+  s1.m_struct.m_a = 3
+  s1.m_struct.m_b = 7
+
+  i = 0           // Break here.
+  fmt.Println ("Got: %d, %d, %d, %s", i, s1.m_struct.m_a,
+               s1.m_struct.m_b, s1.m_string)
+}
diff --git a/gdb/testsuite/gdb.modula2/max-depth.c b/gdb/testsuite/gdb.modula2/max-depth.c
new file mode 100644
index 0000000..c2fd70c
--- /dev/null
+++ b/gdb/testsuite/gdb.modula2/max-depth.c
@@ -0,0 +1,45 @@
+/* Copyright 2019 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/>.  */
+
+#include <string.h>
+
+struct S1
+{
+  int a;
+  int b;
+};
+
+struct S2
+{
+  char str[10];
+  struct S1 s1;
+};
+
+struct S3
+{
+  struct S2 s2;
+};
+
+int
+main ()
+{
+  struct S3 s3;
+
+  memcpy (s3.s2.str, "abcde\0fghi", 10);
+  s3.s2.s1.a = 3;
+  s3.s2.s1.b = 4;
+
+  return 0;	/* Break here.  */
+}
diff --git a/gdb/testsuite/gdb.modula2/max-depth.exp b/gdb/testsuite/gdb.modula2/max-depth.exp
new file mode 100644
index 0000000..ac7edfe
--- /dev/null
+++ b/gdb/testsuite/gdb.modula2/max-depth.exp
@@ -0,0 +1,37 @@
+# Copyright 2019 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/>.
+
+# Test the use of 'set prinnt max-depth' when printing modula2 structures.
+
+standard_testfile
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug quiet}]} {
+    return -1
+}
+
+if { ![runto_main] } then {
+    fail "can't run to main"
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Break here"]
+gdb_continue_to_breakpoint "breakpoint"
+
+gdb_test "set lang modula-2" ".*does not match.*" "switch to modula-2"
+
+gdb_print_expr_at_depths "s3" [list "{...}" \
+				    "{s2 = {...}}" \
+				    "{s2 = {str = \"abcde\\\\000fghi\", s1 = {...}}}" \
+				    "{s2 = {str = \"abcde\\\\000fghi\", s1 = {a = 3, b = 4}}}"]
diff --git a/gdb/testsuite/gdb.python/py-format-string.exp b/gdb/testsuite/gdb.python/py-format-string.exp
index 2f574fb..ebb2074 100644
--- a/gdb/testsuite/gdb.python/py-format-string.exp
+++ b/gdb/testsuite/gdb.python/py-format-string.exp
@@ -672,6 +672,26 @@ proc test_max_elements {} {
   }
 }
 
+# Test the max_depth option for gdb.Value.format_string.
+proc test_max_depth {} {
+    set opts "max_depth=-1"
+    with_test_prefix $opts {
+	check_format_string "a_struct_with_union" $opts
+    }
+    set opts "max_depth=0"
+    with_test_prefix $opts {
+	check_format_string "a_struct_with_union" $opts "\\{\.\.\.\\}"
+    }
+    set opts "max_depth=1"
+    with_test_prefix $opts {
+	check_format_string "a_struct_with_union" $opts "\\{the_union = \\{\.\.\.\\}\\}"
+    }
+    set opts "max_depth=2"
+    with_test_prefix $opts {
+	check_format_string "a_struct_with_union" $opts
+    }
+}
+
 # Test the repeat_threshold option for gdb.Value.format_string.
 proc test_repeat_threshold {} {
   global current_lang
@@ -925,6 +945,7 @@ proc test_all_common {} {
   test_actual_objects
   test_static_members
   test_max_elements
+  test_max_depth
   test_repeat_threshold
   test_format
   # Multiple options mixed together.
diff --git a/gdb/testsuite/gdb.python/py-nested-maps.c b/gdb/testsuite/gdb.python/py-nested-maps.c
new file mode 100644
index 0000000..94107c0
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-nested-maps.c
@@ -0,0 +1,130 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2019 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/>.  */
+
+#include <stdlib.h>
+#include <string.h>
+
+#define FIXED_MAP_SIZE 10
+
+struct key_t
+{
+  int a;
+  int b;
+};
+
+struct value_t
+{
+  int x;
+  int y;
+  int z;
+};
+
+struct map_t
+{
+  const char *name;
+  int length;
+  struct key_t *keys;
+  struct value_t *values;
+
+  /* This field is used only by the pretty printer.  */
+  int show_header;
+};
+
+struct map_map_t
+{
+  int length;
+  struct map_t **values;
+
+  /* This field is used only by the pretty printer.  */
+  int show_header;
+};
+
+struct map_t *
+create_map (const char *name)
+{
+  struct map_t *m = malloc (sizeof (struct map_t));
+  m->name = strdup (name);
+  m->length = 0;
+  m->keys = NULL;
+  m->values = NULL;
+  m->show_header = 0;
+}
+
+void
+add_map_element (struct map_t *m, struct key_t k, struct value_t v)
+{
+  if (m->length == 0)
+    {
+      m->keys = malloc (sizeof (struct key_t) * FIXED_MAP_SIZE);
+      m->values = malloc (sizeof (struct value_t) * FIXED_MAP_SIZE);
+    }
+
+  m->keys[m->length] = k;
+  m->values[m->length] = v;
+  m->length++;
+}
+
+struct map_map_t *
+create_map_map (void)
+{
+  struct map_map_t *mm = malloc (sizeof (struct map_map_t));
+  mm->length = 0;
+  mm->values = NULL;
+  mm->show_header = 0;
+}
+
+void
+add_map_map_element (struct map_map_t *mm, struct map_t *map)
+{
+  if (mm->length == 0)
+    mm->values = malloc (sizeof (struct map_t *) * FIXED_MAP_SIZE);
+
+  mm->values[mm->length] = map;
+  mm->length++;
+}
+
+int
+main (void)
+{
+  struct map_t *m1 = create_map ("m1");
+  struct key_t k1 = {3, 4};
+  struct key_t k2 = {4, 5};
+  struct key_t k3 = {5, 6};
+  struct key_t k4 = {6, 7};
+  struct key_t k5 = {7, 8};
+  struct key_t k6 = {8, 9};
+  struct value_t v1 = {0, 1, 2};
+  struct value_t v2 = {3, 4, 5};
+  struct value_t v3 = {6, 7, 8};
+  struct value_t v4 = {9, 0, 1};
+  struct value_t v5 = {2, 3, 4};
+  struct value_t v6 = {5, 6, 7};
+  add_map_element (m1, k1, v1);
+  add_map_element (m1, k2, v2);
+  add_map_element (m1, k3, v3);
+
+  struct map_t *m2 = create_map ("m2");
+  add_map_element (m2, k4, v4);
+  add_map_element (m2, k5, v5);
+  add_map_element (m2, k6, v6);
+
+  struct map_map_t *mm = create_map_map ();
+  add_map_map_element (mm, m1);
+  add_map_map_element (mm, m2);
+
+  return 0; /* Break here.  */
+}
diff --git a/gdb/testsuite/gdb.python/py-nested-maps.exp b/gdb/testsuite/gdb.python/py-nested-maps.exp
new file mode 100644
index 0000000..81dd99c
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-nested-maps.exp
@@ -0,0 +1,238 @@
+# Copyright (C) 2019 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 tests GDB's python pretty printing of nested map like
+# structures using structures as keys and values, it then tests how
+# 'set print max-depth' affects this printing.
+
+load_lib gdb-python.exp
+
+standard_testfile
+
+# Start with a fresh gdb.
+gdb_exit
+gdb_start
+
+# Skip all tests if Python scripting is not enabled.
+if { [skip_python_tests] } { continue }
+
+standard_testfile
+
+if { [prepare_for_testing "failed to prepare" $testfile $srcfile {debug}] } {
+    return -1
+}
+
+if ![runto_main ] then {
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Break here"]
+gdb_continue_to_breakpoint "run to testing point" ".*Break here.*"
+
+set remote_python_file [gdb_remote_download host \
+			    ${srcdir}/${subdir}/${testfile}.py]
+gdb_test_no_output "source ${remote_python_file}" "load python file"
+
+# Test printing with 'set print pretty off'.
+gdb_test_no_output "set print pretty off"
+with_test_prefix "pretty=off" {
+    gdb_print_expr_at_depths "*m1" \
+	[list \
+	     "\{\\.\\.\\.\}" \
+	     "\{\\\[\{a = 3, b = 4\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 4, b = 5\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 5, b = 6\}\\\] = \{\\.\\.\\.\}\}" \
+	     "\{\\\[\{a = 3, b = 4\}\\\] = \{x = 0, y = 1, z = 2\}, \\\[\{a = 4, b = 5\}\\\] = \{x = 3, y = 4, z = 5\}, \\\[\{a = 5, b = 6\}\\\] = \{x = 6, y = 7, z = 8\}\}" \
+	    ]
+
+    gdb_print_expr_at_depths "*mm" \
+	[list \
+	     "\{\\.\\.\\.\}" \
+	     "\{\\\[$hex \"m1\"\\\] = \{\\.\\.\\.\}, \\\[$hex \"m2\"\\\] = \{\\.\\.\\.\}\}" \
+	     "\{\\\[$hex \"m1\"\\\] = \{\\\[\{a = 3, b = 4\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 4, b = 5\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 5, b = 6\}\\\] = \{\\.\\.\\.\}\}, \\\[$hex \"m2\"\\\] = \{\\\[\{a = 6, b = 7\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 7, b = 8\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 8, b = 9\}\\\] = \{\\.\\.\\.\}\}\}" \
+	     "\{\\\[$hex \"m1\"\\\] = \{\\\[\{a = 3, b = 4\}\\\] = \{x = 0, y = 1, z = 2\}, \\\[\{a = 4, b = 5\}\\\] = \{x = 3, y = 4, z = 5\}, \\\[\{a = 5, b = 6\}\\\] = \{x = 6, y = 7, z = 8\}\}, \\\[$hex \"m2\"\\\] = \{\\\[\{a = 6, b = 7\}\\\] = \{x = 9, y = 0, z = 1\}, \\\[\{a = 7, b = 8\}\\\] = \{x = 2, y = 3, z = 4\}, \\\[\{a = 8, b = 9\}\\\] = \{x = 5, y = 6, z = 7\}\}\}" \
+	    ]
+}
+
+# Now again, but with 'set print pretty on'.
+gdb_test_no_output "set print pretty on"
+with_test_prefix "pretty=on" {
+    gdb_print_expr_at_depths "*m1" \
+	[list \
+	     "\{\\.\\.\\.\}" \
+	     [multi_line \
+		  " = \{" \
+		  "  \\\[\{" \
+		  "    a = 3," \
+		  "    b = 4" \
+		  "  \}\\\] = \{\\.\\.\\.\}," \
+		  "  \\\[\{" \
+		  "    a = 4," \
+		  "    b = 5" \
+		  "  \}\\\] = \{\\.\\.\\.\}," \
+		  "  \\\[\{" \
+		  "    a = 5," \
+		  "    b = 6" \
+		  "  \}\\\] = \{\\.\\.\\.\}" \
+		  "\}" ] \
+	     [multi_line \
+		  " = \{" \
+		  "  \\\[\{" \
+		  "    a = 3," \
+		  "    b = 4" \
+		  "  \}\\\] = \{" \
+		  "    x = 0," \
+		  "    y = 1," \
+		  "    z = 2" \
+		  "  \}," \
+		  "  \\\[\{" \
+		  "    a = 4," \
+		  "    b = 5" \
+		  "  \}\\\] = \{" \
+		  "    x = 3," \
+		  "    y = 4," \
+		  "    z = 5" \
+		  "  \}," \
+		  "  \\\[\{" \
+		  "    a = 5," \
+		  "    b = 6" \
+		  "  \}\\\] = \{" \
+		  "    x = 6," \
+		  "    y = 7," \
+		  "    z = 8" \
+		  "  \}" \
+		  "\}" ] \
+	    ]
+
+     gdb_print_expr_at_depths "*mm" \
+	[list \
+	     "\{\\.\\.\\.\}" \
+	     [multi_line \
+		  " = \{" \
+		  "  \\\[$hex \"m1\"\\\] = \{\\.\\.\\.\}," \
+		  "  \\\[$hex \"m2\"\\\] = \{\\.\\.\\.\}" \
+		  "\}" ] \
+	     [multi_line \
+		  " = \{" \
+		  "  \\\[$hex \"m1\"\\\] = \{" \
+		  "    \\\[\{" \
+		  "      a = 3," \
+		  "      b = 4" \
+		  "    \}\\\] = \{\\.\\.\\.\}," \
+		  "    \\\[\{" \
+		  "      a = 4," \
+		  "      b = 5" \
+		  "    \}\\\] = \{\\.\\.\\.\}," \
+		  "    \\\[\{" \
+		  "      a = 5," \
+		  "      b = 6" \
+		  "    \}\\\] = \{\\.\\.\\.\}" \
+		  "  \}," \
+		  "  \\\[$hex \"m2\"\\\] = \{" \
+		  "    \\\[\{" \
+		  "      a = 6," \
+		  "      b = 7" \
+		  "    \}\\\] = \{\\.\\.\\.\}," \
+		  "    \\\[\{" \
+		  "      a = 7," \
+		  "      b = 8" \
+		  "    \}\\\] = \{\\.\\.\\.\}," \
+		  "    \\\[\{" \
+		  "      a = 8," \
+		  "      b = 9" \
+		  "    \}\\\] = \{\\.\\.\\.\}" \
+		  "  \}" \
+		  "\}" ] \
+	     [multi_line \
+		  " = \{" \
+		  "  \\\[$hex \"m1\"\\\] = \{" \
+		  "    \\\[\{" \
+		  "      a = 3," \
+		  "      b = 4" \
+		  "    \}\\\] = \{" \
+		  "      x = 0," \
+		  "      y = 1," \
+		  "      z = 2" \
+		  "    \}," \
+		  "    \\\[\{" \
+		  "      a = 4," \
+		  "      b = 5" \
+		  "    \}\\\] = \{" \
+		  "      x = 3," \
+		  "      y = 4," \
+		  "      z = 5" \
+		  "    \}," \
+		  "    \\\[\{" \
+		  "      a = 5," \
+		  "      b = 6" \
+		  "    \}\\\] = \{" \
+		  "      x = 6," \
+		  "      y = 7," \
+		  "      z = 8" \
+		  "    \}" \
+		  "  \}," \
+		  "  \\\[$hex \"m2\"\\\] = \{" \
+		  "    \\\[\{" \
+		  "      a = 6," \
+		  "      b = 7" \
+		  "    \}\\\] = \{" \
+		  "      x = 9," \
+		  "      y = 0," \
+		  "      z = 1" \
+		  "    \}," \
+		  "    \\\[\{" \
+		  "      a = 7," \
+		  "      b = 8" \
+		  "    \}\\\] = \{" \
+		  "      x = 2," \
+		  "      y = 3," \
+		  "      z = 4" \
+		  "    \}," \
+		  "    \\\[\{" \
+		  "      a = 8," \
+		  "      b = 9" \
+		  "    \}\\\] = \{" \
+		  "      x = 5," \
+		  "      y = 6," \
+		  "      z = 7" \
+		  "    \}" \
+		  "  \}" \
+		  "\}" ] \
+	    ]
+}
+
+# Test printing with 'set print pretty off', but this time display a
+# top level string (returned from the to_string method) as part of the
+# printed value.
+gdb_test_no_output "set mm->show_header=1"
+gdb_test_no_output "set m1->show_header=1"
+gdb_test_no_output "set m2->show_header=1"
+with_test_prefix "headers=on" {
+    gdb_test_no_output "set print pretty off"
+    with_test_prefix "pretty=off" {
+	gdb_print_expr_at_depths "*m1" \
+	    [list \
+		 "\{\\.\\.\\.\}" \
+		 "pp_map = \{\\\[\{a = 3, b = 4\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 4, b = 5\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 5, b = 6\}\\\] = \{\\.\\.\\.\}\}" \
+		 "pp_map = \{\\\[\{a = 3, b = 4\}\\\] = \{x = 0, y = 1, z = 2\}, \\\[\{a = 4, b = 5\}\\\] = \{x = 3, y = 4, z = 5\}, \\\[\{a = 5, b = 6\}\\\] = \{x = 6, y = 7, z = 8\}\}" \
+		]
+
+	gdb_print_expr_at_depths "*mm" \
+	    [list \
+		 "\{\\.\\.\\.\}" \
+		 "pp_map_map = \{\\\[$hex \"m1\"\\\] = \{\\.\\.\\.\}, \\\[$hex \"m2\"\\\] = \{\\.\\.\\.\}\}" \
+		 "pp_map_map = \{\\\[$hex \"m1\"\\\] = pp_map = \{\\\[\{a = 3, b = 4\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 4, b = 5\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 5, b = 6\}\\\] = \{\\.\\.\\.\}\}, \\\[$hex \"m2\"\\\] = pp_map = \{\\\[\{a = 6, b = 7\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 7, b = 8\}\\\] = \{\\.\\.\\.\}, \\\[\{a = 8, b = 9\}\\\] = \{\\.\\.\\.\}\}\}" \
+		 "pp_map_map = \{\\\[$hex \"m1\"\\\] = pp_map = \{\\\[\{a = 3, b = 4\}\\\] = \{x = 0, y = 1, z = 2\}, \\\[\{a = 4, b = 5\}\\\] = \{x = 3, y = 4, z = 5\}, \\\[\{a = 5, b = 6\}\\\] = \{x = 6, y = 7, z = 8\}\}, \\\[$hex \"m2\"\\\] = pp_map = \{\\\[\{a = 6, b = 7\}\\\] = \{x = 9, y = 0, z = 1\}, \\\[\{a = 7, b = 8\}\\\] = \{x = 2, y = 3, z = 4\}, \\\[\{a = 8, b = 9\}\\\] = \{x = 5, y = 6, z = 7\}\}\}" \
+		]
+    }
+}
diff --git a/gdb/testsuite/gdb.python/py-nested-maps.py b/gdb/testsuite/gdb.python/py-nested-maps.py
new file mode 100644
index 0000000..d3fdf59
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-nested-maps.py
@@ -0,0 +1,135 @@
+# Copyright (C) 2019 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 file is part of the GDB testsuite.  It tests GDB's printing of
+# nested map like structures.
+
+import re
+import gdb
+
+def _iterator1 (pointer, len):
+    while len > 0:
+        map = pointer.dereference()
+        yield ('', map['name'])
+        yield ('', map.dereference())
+        pointer += 1
+        len -= 1
+
+def _iterator2 (pointer1, pointer2, len):
+    while len > 0:
+        yield ("", pointer1.dereference())
+        yield ("", pointer2.dereference())
+        pointer1 += 1
+        pointer2 += 1
+        len -= 1
+
+class pp_map (object):
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        if (self.val['show_header'] == 0):
+            return None
+        else:
+            return "pp_map"
+
+    def children(self):
+        return _iterator2(self.val['keys'],
+                          self.val['values'],
+                          self.val['length'])
+
+    def display_hint (self):
+        return 'map'
+
+class pp_map_map (object):
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        if (self.val['show_header'] == 0):
+            return None
+        else:
+            return "pp_map_map"
+
+    def children(self):
+        return _iterator1(self.val['values'],
+                          self.val['length'])
+
+    def display_hint (self):
+        return 'map'
+
+def lookup_function (val):
+    "Look-up and return a pretty-printer that can print val."
+
+    # Get the type.
+    type = val.type
+
+    # If it points to a reference, get the reference.
+    if type.code == gdb.TYPE_CODE_REF:
+        type = type.target ()
+
+    # Get the unqualified type, stripped of typedefs.
+    type = type.unqualified ().strip_typedefs ()
+
+    # Get the type name.
+    typename = type.tag
+
+    if typename == None:
+        return None
+
+    # Iterate over local dictionary of types to determine
+    # if a printer is registered for that type.  Return an
+    # instantiation of the printer if found.
+    for function in pretty_printers_dict:
+        if function.match (typename):
+            return pretty_printers_dict[function] (val)
+
+    # Cannot find a pretty printer.  Return None.
+    return None
+
+# Lookup a printer for VAL in the typedefs dict.
+def lookup_typedefs_function (val):
+    "Look-up and return a pretty-printer that can print val (typedefs)."
+
+    # Get the type.
+    type = val.type
+
+    if type == None or type.name == None or type.code != gdb.TYPE_CODE_TYPEDEF:
+        return None
+
+    # Iterate over local dictionary of typedef types to determine if a
+    # printer is registered for that type.  Return an instantiation of
+    # the printer if found.
+    for function in typedefs_pretty_printers_dict:
+        if function.match (type.name):
+            return typedefs_pretty_printers_dict[function] (val)
+
+    # Cannot find a pretty printer.
+    return None
+
+def register_pretty_printers ():
+    pretty_printers_dict[re.compile ('^struct map_t$')] = pp_map
+    pretty_printers_dict[re.compile ('^map_t$')] = pp_map
+    pretty_printers_dict[re.compile ('^struct map_map_t$')] = pp_map_map
+    pretty_printers_dict[re.compile ('^map_map_t$')] = pp_map_map
+
+# Dict for struct types with typedefs fully stripped.
+pretty_printers_dict = {}
+# Dict for typedef types.
+typedefs_pretty_printers_dict = {}
+
+register_pretty_printers ()
+gdb.pretty_printers.append (lookup_function)
+gdb.pretty_printers.append (lookup_typedefs_function)
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index f0f4334..25d370e 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1390,6 +1390,36 @@ proc gdb_test_stdio {command inferior_pattern {gdb_pattern ""} {message ""}} {
     return $res
 }
 
+# get_print_expr_at_depths EXP OUTPUTS
+#
+# Used for testing 'set print max-depth'.  Prints the expression EXP
+# with 'set print max-depth' set to various depths.  OUTPUTS is a list
+# of `n` different patterns to match at each of the depths from 0 to
+# (`n` - 1).
+#
+# This proc does one final check with the max-depth set to 'unlimited'
+# which is tested against the last pattern in the OUTPUTS list.  The
+# OUTPUTS list is therefore required to match every depth from 0 to a
+# depth where the whole of EXP is printed with no ellipsis.
+#
+# This proc leaves the 'set print max-depth' set to 'unlimited'.
+proc gdb_print_expr_at_depths {exp outputs} {
+    for { set depth 0 } { $depth <= [llength $outputs] } { incr depth } {
+	if { $depth == [llength $outputs] } {
+	    set expected_result [lindex $outputs [expr [llength $outputs] - 1]]
+	    set depth_string "unlimited"
+	} else {
+	    set expected_result [lindex $outputs $depth]
+	    set depth_string $depth
+	}
+
+	with_test_prefix "exp='$exp': depth=${depth_string}" {
+	    gdb_test_no_output "set print max-depth ${depth_string}"
+	    gdb_test "p $exp" "$expected_result"
+	}
+    }
+}
+
 
 
 # Issue a PASS and return true if evaluating CONDITION in the caller's