From 02c6f3f1fc2af7ad02bc649f0adfb479bf163441 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Mon, 10 Aug 2020 05:21:06 -0600 Subject: [PATCH] Do not auto-dereference null pointers in Ada MI varobj The Ada varobj code automatically dereferences access types. This is often handy, but it also does so for null pointers -- showing children with empty values. These children are weird, but even weirder when a variant type is involved, because only the non-varying parts of the type are displayed. This behavior conflicts a bit with my ongoing quest to move the Ada code to use DWARF rather than gnat encodings, in that reproducing this behavior with the DWARF code seems rather hacky. So, this patch instead changes the Ada varobj code so that it does not automatically dereference null pointers. As this patch only affects Ada, and it was already reviewed internally by Joel, I am checking it in. 2020-09-02 Tom Tromey * ada-varobj.c (ada_varobj_get_ptr_number_of_children): Return 0 for null pointers. (ada_varobj_adjust_for_child_access): Special-case null pointers. gdb/testsuite/ChangeLog 2020-09-02 Tom Tromey * gdb.ada/mi_var_access.exp: Test children of access variable. * gdb.ada/mi_var_access/mi_access.adb: Add new stop markers. * gdb.ada/mi_var_array.exp: Update. --- gdb/ChangeLog | 6 +++++ gdb/ada-varobj.c | 6 +++++ gdb/testsuite/ChangeLog | 6 +++++ gdb/testsuite/gdb.ada/mi_var_access.exp | 22 +++++++++++++++++++ .../gdb.ada/mi_var_access/mi_access.adb | 4 ++-- gdb/testsuite/gdb.ada/mi_var_array.exp | 10 +-------- 6 files changed, 43 insertions(+), 11 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index ab003afa3e4..8ace83b3271 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2020-09-02 Tom Tromey + + * ada-varobj.c (ada_varobj_get_ptr_number_of_children): Return 0 + for null pointers. + (ada_varobj_adjust_for_child_access): Special-case null pointers. + 2020-09-01 Simon Marchi * bcache.h (struct bcache) : Change type of `added` to diff --git a/gdb/ada-varobj.c b/gdb/ada-varobj.c index a72653af37a..f2a291ad5e5 100644 --- a/gdb/ada-varobj.c +++ b/gdb/ada-varobj.c @@ -209,6 +209,8 @@ ada_varobj_adjust_for_child_access (struct value **value, if ((*type)->code () == TYPE_CODE_PTR && (TYPE_TARGET_TYPE (*type)->code () == TYPE_CODE_STRUCT || TYPE_TARGET_TYPE (*type)->code () == TYPE_CODE_UNION) + && *value != nullptr + && value_as_address (*value) != 0 && !ada_is_array_descriptor_type (TYPE_TARGET_TYPE (*type)) && !ada_is_constrained_packed_array_type (TYPE_TARGET_TYPE (*type))) ada_varobj_ind (*value, *type, value, type); @@ -333,6 +335,10 @@ ada_varobj_get_ptr_number_of_children (struct value *parent_value, || child_type->code () == TYPE_CODE_VOID) return 0; + /* Only show children for non-null pointers. */ + if (parent_value == nullptr || value_as_address (parent_value) == 0) + return 0; + /* All other types have 1 child. */ return 1; } diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 7e60a11c3dd..63dcad7d99e 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2020-09-02 Tom Tromey + + * gdb.ada/mi_var_access.exp: Test children of access variable. + * gdb.ada/mi_var_access/mi_access.adb: Add new stop markers. + * gdb.ada/mi_var_array.exp: Update. + 2020-08-31 Kevin Buettner * gdb.base/corefile.exp (warning-free): XFAIL test when running diff --git a/gdb/testsuite/gdb.ada/mi_var_access.exp b/gdb/testsuite/gdb.ada/mi_var_access.exp index 5ffc0ae8772..14e899221e3 100644 --- a/gdb/testsuite/gdb.ada/mi_var_access.exp +++ b/gdb/testsuite/gdb.ada/mi_var_access.exp @@ -50,3 +50,25 @@ mi_continue_to_line \ mi_gdb_test "-var-create A_String_Access * A_String_Access" \ "\\^done,name=\"A_String_Access\",numchild=\"1\",.*" \ "Create varobj" + +set bp_location [gdb_get_line_number "STOP2" ${testdir}/mi_access.adb] +mi_continue_to_line \ + "mi_access.adb:$bp_location" \ + "stop at stop 2" + +mi_gdb_test "-var-update A_String_Access" \ + [string_to_regexp {^done,changelist=[{name="A_String_Access",in_scope="true",type_changed="false",has_more="0"}]}] \ + "update at stop 2" + +mi_gdb_test "-var-list-children A_String_Access" \ + [string_to_regexp {^done,numchild="1",children=[child={name="A_String_Access.A_String_Access.all",exp="A_String_Access.all",numchild="3",type="array (3 .. 5) of character",thread-id="1"}],has_more="0"}] \ + "list children at stop 2" + +set bp_location [gdb_get_line_number "STOP3" ${testdir}/mi_access.adb] +mi_continue_to_line \ + "mi_access.adb:$bp_location" \ + "stop at stop 3" + +mi_gdb_test "-var-update A_String_Access" \ + [string_to_regexp {^done,changelist=[{name="A_String_Access",in_scope="true",type_changed="true",new_type="pck.string_access",new_num_children="0",has_more="0"}]}] \ + "update at stop 3" diff --git a/gdb/testsuite/gdb.ada/mi_var_access/mi_access.adb b/gdb/testsuite/gdb.ada/mi_var_access/mi_access.adb index d5f5f881463..b1dc7be1c3a 100644 --- a/gdb/testsuite/gdb.ada/mi_var_access/mi_access.adb +++ b/gdb/testsuite/gdb.ada/mi_var_access/mi_access.adb @@ -24,7 +24,7 @@ begin A_String (4) := '6'; A_String_Access := Copy (A_String); A_Pointer.P := A_String_Access; - Do_Nothing (A_String_Access'Address); + Do_Nothing (A_String_Access'Address); -- STOP2 A_String_Access (4) := 'a'; Do_Nothing (A_Pointer'Address); A_String_Access := Copy("Hi"); @@ -32,6 +32,6 @@ begin Do_Nothing (A_String_Access'Address); A_String_Access := null; A_Pointer.P := null; - Do_Nothing (A_Pointer'Address); + Do_Nothing (A_Pointer'Address); -- STOP3 Do_Nothing (A_String'Address); end Mi_Access; diff --git a/gdb/testsuite/gdb.ada/mi_var_array.exp b/gdb/testsuite/gdb.ada/mi_var_array.exp index fdc2249ba02..4ef213b7a6e 100644 --- a/gdb/testsuite/gdb.ada/mi_var_array.exp +++ b/gdb/testsuite/gdb.ada/mi_var_array.exp @@ -52,14 +52,6 @@ foreach_with_prefix scenario {none all minimal} { "stop at start of main Ada procedure" mi_gdb_test "-var-create vta * vta" \ - "\\^done,name=\"vta\",numchild=\"2\",.*" \ + "\\^done,name=\"vta\",numchild=\"0\",.*" \ "create bt varobj" - - # In the "minimal" mode, we don't currently have the ability to - # print the subrange type properly. So, we just allow anything - # for the array range here. The correct result would be to fix - # this to read "(1 .. n)". - mi_gdb_test "-var-list-children vta" \ - "\\^done,numchild=\"2\",children=\\\[child={name=\"vta.n\",exp=\"n\",numchild=\"0\",type=\"bar\\.int\",thread-id=\"$decimal\"},child={name=\"vta.f\",exp=\"f\",numchild=\"0\",type=\"array .* of character\",thread-id=\"$decimal\"}\\\],.*" \ - "list vta's children" } -- 2.30.2