[PATCH 4/9] Change dbxread.c to use type-safe registry

[Tom Tromey <tromey at adacore dot com>]

This changes dbxread.c to use the type-safe registry.  In a couple of
spots, you'll see that dbx_objfile_data_key.emplace is called but the
result is not used; this is because those functions refer to the key
via the various DBX_* macros.

gdb/ChangeLog
2019-07-10  Tom Tromey  <tromey@adacore.com>

	* gdb-stabs.h (struct dbx_symfile_info): Add initializers and
	destructor.
	(dbx_objfile_data_key): Change type and declare later.
	(DBX_SYMFILE_INFO): Rewrite.
	* dbxread.c (dbx_objfile_data_key): Change type.
	(dbx_symfile_init): Update.
	(~dbx_symfile_info): Rename from dbx_free_symfile_info.  Update.
	(coffstab_build_psymtabs, elfstab_build_psymtabs)
	(stabsect_build_psymtabs, _initialize_dbxread): Update.
---
 gdb/ChangeLog   | 12 ++++++++++++
 gdb/dbxread.c   | 32 +++++++++-----------------------
 gdb/gdb-stabs.h | 41 +++++++++++++++++++++--------------------
 3 files changed, 42 insertions(+), 43 deletions(-)

diff --git a/gdb/dbxread.c b/gdb/dbxread.c
index 307debd2824..00eeb317dc4 100644
--- a/gdb/dbxread.c
+++ b/gdb/dbxread.c
@@ -61,7 +61,7 @@
 
 /* Key for dbx-associated data.  */
 
-const struct objfile_data *dbx_objfile_data_key;
+objfile_key<dbx_symfile_info> dbx_objfile_data_key;
 
 /* We put a pointer to this structure in the read_symtab_private field
    of the psymtab.  */
@@ -590,11 +590,9 @@ dbx_symfile_init (struct objfile *objfile)
   char *name = bfd_get_filename (sym_bfd);
   asection *text_sect;
   unsigned char size_temp[DBX_STRINGTAB_SIZE_SIZE];
-  struct dbx_symfile_info *dbx;
 
   /* Allocate struct to keep track of the symfile.  */
-  dbx = XCNEW (struct dbx_symfile_info);
-  set_objfile_data (objfile, dbx_objfile_data_key, dbx);
+  dbx_objfile_data_key.emplace (objfile);
 
   DBX_TEXT_SECTION (objfile) = bfd_get_section_by_name (sym_bfd, ".text");
   DBX_DATA_SECTION (objfile) = bfd_get_section_by_name (sym_bfd, ".data");
@@ -703,15 +701,12 @@ dbx_symfile_finish (struct objfile *objfile)
   free_header_files ();
 }
 
-static void
-dbx_free_symfile_info (struct objfile *objfile, void *arg)
+dbx_symfile_info::~dbx_symfile_info ()
 {
-  struct dbx_symfile_info *dbx = (struct dbx_symfile_info *) arg;
-
-  if (dbx->header_files != NULL)
+  if (header_files != NULL)
     {
-      int i = dbx->n_header_files;
-      struct header_file *hfiles = dbx->header_files;
+      int i = n_header_files;
+      struct header_file *hfiles = header_files;
 
       while (--i >= 0)
 	{
@@ -720,8 +715,6 @@ dbx_free_symfile_info (struct objfile *objfile, void *arg)
 	}
       xfree (hfiles);
     }
-
-  xfree (dbx);
 }
 
 
@@ -2952,8 +2945,7 @@ coffstab_build_psymtabs (struct objfile *objfile,
   unsigned int stabsize;
 
   /* Allocate struct to keep track of stab reading.  */
-  struct dbx_symfile_info *dbx = XCNEW (struct dbx_symfile_info);
-  set_objfile_data (objfile, dbx_objfile_data_key, dbx);
+  dbx_objfile_data_key.emplace (objfile);
 
   DBX_TEXT_ADDR (objfile) = textaddr;
   DBX_TEXT_SIZE (objfile) = textsize;
@@ -3041,8 +3033,7 @@ elfstab_build_psymtabs (struct objfile *objfile, asection *stabsect,
   stabsread_new_init ();
 
   /* Allocate struct to keep track of stab reading.  */
-  struct dbx_symfile_info *dbx = XCNEW (struct dbx_symfile_info);
-  set_objfile_data (objfile, dbx_objfile_data_key, dbx);
+  dbx_objfile_data_key.emplace (objfile);
 
   /* Find the first and last text address.  dbx_symfile_read seems to
      want this.  */
@@ -3122,7 +3113,6 @@ stabsect_build_psymtabs (struct objfile *objfile, char *stab_name,
   asection *stabsect;
   asection *stabstrsect;
   asection *text_sect;
-  struct dbx_symfile_info *dbx;
 
   stabsect = bfd_get_section_by_name (sym_bfd, stab_name);
   stabstrsect = bfd_get_section_by_name (sym_bfd, stabstr_name);
@@ -3135,8 +3125,7 @@ stabsect_build_psymtabs (struct objfile *objfile, char *stab_name,
 	     "but not string section (%s)"),
 	   stab_name, stabstr_name);
 
-  dbx = XCNEW (struct dbx_symfile_info);
-  set_objfile_data (objfile, dbx_objfile_data_key, dbx);
+  dbx_objfile_data_key.emplace (objfile);
 
   text_sect = bfd_get_section_by_name (sym_bfd, text_name);
   if (!text_sect)
@@ -3201,7 +3190,4 @@ void
 _initialize_dbxread (void)
 {
   add_symtab_fns (bfd_target_aout_flavour, &aout_sym_fns);
-
-  dbx_objfile_data_key
-    = register_objfile_data_with_cleanup (NULL, dbx_free_symfile_info);
 }
diff --git a/gdb/gdb-stabs.h b/gdb/gdb-stabs.h
index 3b64d328f5c..dfdd20be06d 100644
--- a/gdb/gdb-stabs.h
+++ b/gdb/gdb-stabs.h
@@ -27,41 +27,42 @@
    each others' functions as required.  */
 
 
-/* The tag used to find the DBX info attached to an objfile.  This is
-   global because it is referenced by several modules.  */
-extern const struct objfile_data *dbx_objfile_data_key;
-
 /* Information is passed among various dbxread routines for accessing
    symbol files.  A pointer to this structure is kept in the objfile,
    using the dbx_objfile_data_key.  */
 
 struct dbx_symfile_info
   {
-    CORE_ADDR text_addr;	/* Start of text section */
-    int text_size;		/* Size of text section */
-    int symcount;		/* How many symbols are there in the file */
-    char *stringtab;		/* The actual string table */
-    int stringtab_size;		/* Its size */
-    file_ptr symtab_offset;	/* Offset in file to symbol table */
-    int symbol_size;		/* Bytes in a single symbol */
+    ~dbx_symfile_info ();
+
+    CORE_ADDR text_addr = 0;	/* Start of text section */
+    int text_size = 0;		/* Size of text section */
+    int symcount = 0;		/* How many symbols are there in the file */
+    char *stringtab = nullptr;		/* The actual string table */
+    int stringtab_size = 0;		/* Its size */
+    file_ptr symtab_offset = 0;	/* Offset in file to symbol table */
+    int symbol_size = 0;		/* Bytes in a single symbol */
 
     /* See stabsread.h for the use of the following.  */
-    struct header_file *header_files;
-    int n_header_files;
-    int n_allocated_header_files;
+    struct header_file *header_files = nullptr;
+    int n_header_files = 0;
+    int n_allocated_header_files = 0;
 
     /* Pointers to BFD sections.  These are used to speed up the building of
        minimal symbols.  */
-    asection *text_section;
-    asection *data_section;
-    asection *bss_section;
+    asection *text_section = nullptr;
+    asection *data_section = nullptr;
+    asection *bss_section = nullptr;
 
     /* Pointer to the separate ".stab" section, if there is one.  */
-    asection *stab_section;
+    asection *stab_section = nullptr;
   };
 
-#define DBX_SYMFILE_INFO(o) \
-  ((struct dbx_symfile_info *) objfile_data ((o), dbx_objfile_data_key))
+/* The tag used to find the DBX info attached to an objfile.  This is
+   global because it is referenced by several modules.  */
+extern objfile_key<dbx_symfile_info> dbx_objfile_data_key;
+
+#define DBX_SYMFILE_INFO(o)	(dbx_objfile_data_key.get (o))
 #define DBX_TEXT_ADDR(o)	(DBX_SYMFILE_INFO(o)->text_addr)
 #define DBX_TEXT_SIZE(o)	(DBX_SYMFILE_INFO(o)->text_size)
 #define DBX_SYMCOUNT(o)		(DBX_SYMFILE_INFO(o)->symcount)
-- 
2.20.1