Add attribute::value_as_string method

The full DIE reader checks that an attribute has a "string" form in
some spots, but the partial DIE reader does not.  This patch brings
the two readers in sync for one specific case, namely when examining
the linkage name.  This avoids regressions in an existing DWARF test
case.

A full fix for this problem would be preferable.  An accessor like
DW_STRING should always check the form.  However, I haven't attempted
that in this series.

Also the fact that the partial and full readers can disagree like this
is a design flaw.

gdb/ChangeLog
2020-04-24  Tom Tromey  <tom@tromey.com>

	* dwarf2/read.c (partial_die_info::read) <case
	DW_AT_linkage_name>: Use value_as_string.
	(dwarf2_string_attr): Use value_as_string.
	* dwarf2/attribute.h (struct attribute) <value_as_string>: Declare
	method.
	* dwarf2/attribute.c (attribute::value_as_string): New method.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 6a8d82fd5ac6e44dd92df86161df1bb27c5bcb2c..df43ffd296e180db8427849761a580e2d3c31f7a 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2020-04-24  Tom Tromey  <tom@tromey.com>
+
+       * dwarf2/read.c (partial_die_info::read) <case
+       DW_AT_linkage_name>: Use value_as_string.
+       (dwarf2_string_attr): Use value_as_string.
+       * dwarf2/attribute.h (struct attribute) <value_as_string>: Declare
+       method.
+       * dwarf2/attribute.c (attribute::value_as_string): New method.
+
 2020-04-24  Tom Tromey  <tom@tromey.com>
 
        * symtab.c (general_symbol_info::natural_name)

diff --git a/gdb/dwarf2/attribute.c b/gdb/dwarf2/attribute.c
index 9ceacf0409e7fb5468b14b4861d1e47711faf51a..9f808aa79043b1c5b93b9448598d7b1cb2229d62 100644 (file)
--- a/gdb/dwarf2/attribute.c
+++ b/gdb/dwarf2/attribute.c
@@ -61,6 +61,24 @@ attribute::value_as_address () const
 
 /* See attribute.h.  */
 
+const char *
+attribute::value_as_string () const
+{
+  if (form == DW_FORM_strp || form == DW_FORM_line_strp
+      || form == DW_FORM_string
+      || form == DW_FORM_strx
+      || form == DW_FORM_strx1
+      || form == DW_FORM_strx2
+      || form == DW_FORM_strx3
+      || form == DW_FORM_strx4
+      || form == DW_FORM_GNU_str_index
+      || form == DW_FORM_GNU_strp_alt)
+    return DW_STRING (this);
+  return nullptr;
+}
+
+/* See attribute.h.  */
+
 bool
 attribute::form_is_block () const
 {

diff --git a/gdb/dwarf2/attribute.h b/gdb/dwarf2/attribute.h
index 69b33513ad63f3c0ad70247513592f945ffac54f..a9cabd69f9fa2360221a9580a0c36dc742c8c420 100644 (file)
--- a/gdb/dwarf2/attribute.h
+++ b/gdb/dwarf2/attribute.h
@@ -46,6 +46,10 @@ struct attribute
      attribute's form into account.  */
   CORE_ADDR value_as_address () const;
 
+  /* If the attribute has a string form, return the string value;
+     otherwise return NULL.  */
+  const char *value_as_string () const;
+
   /* Return non-zero if ATTR's value is a section offset --- classes
      lineptr, loclistptr, macptr or rangelistptr --- or zero, otherwise.
      You may use DW_UNSND (attr) to retrieve such offsets.

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index a22139480042d14213d73e7d097de522bfdcda6e..5663d7dfb966e257306191f443a1f780c5af76df 100644 (file)
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -18300,7 +18300,7 @@ partial_die_info::read (const struct die_reader_specs *reader,
          /* Note that both forms of linkage name might appear.  We
             assume they will be the same, and we only store the last
             one we see.  */
-         linkage_name = DW_STRING (&attr);
+         linkage_name = attr.value_as_string ();
          /* rustc emits invalid values for DW_AT_linkage_name.  Ignore these.
             See https://github.com/rust-lang/rust/issues/32925.  */
          if (cu->language == language_rust && linkage_name != NULL
@@ -19485,17 +19485,8 @@ dwarf2_string_attr (struct die_info *die, unsigned int name, struct dwarf2_cu *c
 
   if (attr != NULL)
     {
-      if (attr->form == DW_FORM_strp || attr->form == DW_FORM_line_strp
-         || attr->form == DW_FORM_string
-         || attr->form == DW_FORM_strx
-         || attr->form == DW_FORM_strx1
-         || attr->form == DW_FORM_strx2
-         || attr->form == DW_FORM_strx3
-         || attr->form == DW_FORM_strx4
-         || attr->form == DW_FORM_GNU_str_index
-         || attr->form == DW_FORM_GNU_strp_alt)
-       str = DW_STRING (attr);
-      else
+      str = attr->value_as_string ();
+      if (str == nullptr)
         complaint (_("string type expected for attribute %s for "
                     "DIE at %s in module %s"),
                   dwarf_attr_name (name), sect_offset_str (die->sect_off),