[binutils-gdb] Allow re-assigning to convenience variables

[binutils-gdb] Allow re-assigning to convenience variables

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=55708e99aca33f2ee9036732d778cd5899d2a2b0

commit 55708e99aca33f2ee9036732d778cd5899d2a2b0
Author: Tom Tromey <tromey@adacore.com>
Date:   Tue Nov 5 10:12:27 2019 -0700

    Allow re-assigning to convenience variables
    
    A customer reported somewhat odd gdb behavior, where re-assigning an
    array or string to a convenience variable would yield "Too many array
    elements".  A test case is:
    
        (gdb) p $x = "x"
        (gdb) p $x = "xyz"
    
    This patch fixes the problem by making a special case in the evaluator
    for assignment to convenience variables, which seems like the correct
    behavior.
    
    Note that a previous patch implemented this for Ada, see commit
    f411722cb ("Allow re-assigning to convenience variables").
    
    gdb/ChangeLog
    2019-11-14  Tom Tromey  <tromey@adacore.com>
    
    	* eval.c (evaluate_subexp_standard) <BINOP_ASSIGN>: Do not pass an
    	expected type for the RHS if the LHS is a convenience variable.
    
    gdb/testsuite/ChangeLog
    2019-11-14  Tom Tromey  <tromey@adacore.com>
    
    	* gdb.base/gdbvars.exp (test_convenience_variables): Add
    	regression tests.
    
    Change-Id: I5e66a2d243931a5c43c7af4bc9f6717464c2477e

Diff:
---
 gdb/ChangeLog                      |  5 +++++
 gdb/eval.c                         |  9 ++++++++-
 gdb/testsuite/ChangeLog            |  5 +++++
 gdb/testsuite/gdb.base/gdbvars.exp | 15 +++++++++++++++
 4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 719574f..1a84242 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-14  Tom Tromey  <tromey@adacore.com>
+
+	* eval.c (evaluate_subexp_standard) <BINOP_ASSIGN>: Do not pass an
+	expected type for the RHS if the LHS is a convenience variable.
+
 2019-11-14  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* unittests/vec-utils-selftests.c (unordered_remove_tests::obj):
diff --git a/gdb/eval.c b/gdb/eval.c
index 139fd68..71e79d6 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -2151,7 +2151,14 @@ evaluate_subexp_standard (struct type *expect_type,
 
     case BINOP_ASSIGN:
       arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
-      arg2 = evaluate_subexp (value_type (arg1), exp, pos, noside);
+      /* Special-case assignments where the left-hand-side is a
+	 convenience variable -- in these, don't bother setting an
+	 expected type.  This avoids a weird case where re-assigning a
+	 string or array to an internal variable could error with "Too
+	 many array elements".  */
+      arg2 = evaluate_subexp (VALUE_LVAL (arg1) == lval_internalvar
+			      ? NULL_TYPE : value_type (arg1),
+			      exp, pos, noside);
 
       if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
 	return arg1;
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7416b82..3a4d229 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-14  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.base/gdbvars.exp (test_convenience_variables): Add
+	regression tests.
+
 2019-11-12  Tom Tromey  <tom@tromey.com>
 
 	* lib/tuiterm.exp (_accept): Add wait_for parameter.  Check output
diff --git a/gdb/testsuite/gdb.base/gdbvars.exp b/gdb/testsuite/gdb.base/gdbvars.exp
index 8259115..a4e5b41 100644
--- a/gdb/testsuite/gdb.base/gdbvars.exp
+++ b/gdb/testsuite/gdb.base/gdbvars.exp
@@ -51,6 +51,21 @@ proc test_convenience_variables {} {
 
     gdb_test "print \$bar"		" = void" \
 	"Print contents of uninitialized convenience variable"
+
+
+    gdb_test "print \$str = \"some string\"" \
+	" = \"some string\"" \
+	"Set convenience variable to string value"
+    gdb_test "print \$str = \"some other string\"" \
+	" = \"some other string\"" \
+	"Change convenience variable to different string value"
+
+    gdb_test "print \$arr = {1, 2, 3}" \
+	" = \\{1, 2, 3\\}" \
+	"Set convenience variable to array value"
+    gdb_test "print \$arr = {0, 1, 2, 3}" \
+	" = \\{0, 1, 2, 3\\}" \
+	"Set convenience variable to different array value"
 }
 
 proc test_convenience_functions {} {

[binutils-gdb] Allow re-assigning to convenience variables

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f411722cbc18820e5266ec4c2aadd2269eb15447

commit f411722cbc18820e5266ec4c2aadd2269eb15447
Author: Tom Tromey <tromey@adacore.com>
Date:   Wed Jun 5 10:53:16 2019 -0600

    Allow re-assigning to convenience variables
    
    In Ada mode, re-assigning an array of a different size to a
    convenience variable will cause an error:
    
        (gdb) set lang ada
        (gdb) set $v := "abc"
        (gdb) set $v := "abcd"
        cannot assign arrays of different length
    
    However, this does not really make sense -- instead, it should always
    be possible to overwrite a convenience variable.
    
    This patch fixes this bug.
    
    This was reviewed off-list by Joel.  I'm checking it in.
    
    gdb/ChangeLog
    2019-06-14  Tom Tromey  <tromey@adacore.com>
    
    	* ada-lang.c (ada_evaluate_subexp) <case BINOP_ASSIGN>: Always
    	allow assignment to an internalvar.
    
    gdb/testsuite/ChangeLog
    2019-06-14  Tom Tromey  <tromey@adacore.com>
    
    	* gdb.ada/set_wstr.exp: Add reassignment test.

Diff:
---
 gdb/ChangeLog                      | 5 +++++
 gdb/ada-lang.c                     | 6 +++++-
 gdb/testsuite/ChangeLog            | 4 ++++
 gdb/testsuite/gdb.ada/set_wstr.exp | 5 +++++
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 9fbfcfa..ee3377c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2019-06-14  Tom Tromey  <tromey@adacore.com>
 
+	* ada-lang.c (ada_evaluate_subexp) <case BINOP_ASSIGN>: Always
+	allow assignment to an internalvar.
+
+2019-06-14  Tom Tromey  <tromey@adacore.com>
+
 	* ada-lex.l: Allow "_" in attribute names.
 
 2019-06-14  Tom Tromey  <tromey@adacore.com>
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 1f0ada3..1b5f183 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -10486,7 +10486,11 @@ ada_evaluate_subexp (struct type *expect_type, struct expression *exp,
       arg2 = evaluate_subexp (type, exp, pos, noside);
       if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
         return arg1;
-      if (ada_is_fixed_point_type (value_type (arg1)))
+      if (VALUE_LVAL (arg1) == lval_internalvar)
+	{
+	  /* Nothing.  */
+	}
+      else if (ada_is_fixed_point_type (value_type (arg1)))
         arg2 = cast_to_fixed (value_type (arg1), arg2);
       else if (ada_is_fixed_point_type (value_type (arg2)))
         error
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 9bfd570..8219486 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2019-06-14  Tom Tromey  <tromey@adacore.com>
 
+	* gdb.ada/set_wstr.exp: Add reassignment test.
+
+2019-06-14  Tom Tromey  <tromey@adacore.com>
+
 	* gdb.ada/formatted_ref.exp (test_p_x_addr): Check
 	'unchecked_access and 'unrestricted_access as well.
 
diff --git a/gdb/testsuite/gdb.ada/set_wstr.exp b/gdb/testsuite/gdb.ada/set_wstr.exp
index 0c5c42c..ac70985 100644
--- a/gdb/testsuite/gdb.ada/set_wstr.exp
+++ b/gdb/testsuite/gdb.ada/set_wstr.exp
@@ -72,3 +72,8 @@ gdb_test "print rws" \
 
 gdb_test "set variable www := \"1#2#3#4#5#\"" \
          "cannot assign arrays of different length"
+
+# However, reassigning an array of a different length should work when
+# the LHS is a convenience variable.
+gdb_test_no_output "set variable \$str := \"1234\""
+gdb_test_no_output "set variable \$str := \"12345\""