Remove cleanups from check_fast_tracepoint_sals

This changes the gdbarch fast_tracepoint_valid_at method to use a
std::string as its out parameter, and then updates all the uses.  This
allows removing a cleanup from breakpoint.c.

Regression tested by the buildbot.

ChangeLog
2018-02-24  Tom Tromey  <tom@tromey.com>

	* i386-tdep.c (i386_fast_tracepoint_valid_at): "msg" now a
	std::string.
	* gdbarch.sh (fast_tracepoint_valid_at): Change "msg" to a
	std::string*.
	* gdbarch.c: Rebuild.
	* gdbarch.h: Rebuild.
	* breakpoint.c (check_fast_tracepoint_sals): Use std::string.
	* arch-utils.h (default_fast_tracepoint_valid_at): Update.
	* arch-utils.c (default_fast_tracepoint_valid_at): "msg" now a
	std::string*.

8 files changed, 28 insertions, 23 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5297dcb..df920f8 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,16 @@
+2018-02-24  Tom Tromey  <tom@tromey.com>
+
+	* i386-tdep.c (i386_fast_tracepoint_valid_at): "msg" now a
+	std::string.
+	* gdbarch.sh (fast_tracepoint_valid_at): Change "msg" to a
+	std::string*.
+	* gdbarch.c: Rebuild.
+	* gdbarch.h: Rebuild.
+	* breakpoint.c (check_fast_tracepoint_sals): Use std::string.
+	* arch-utils.h (default_fast_tracepoint_valid_at): Update.
+	* arch-utils.c (default_fast_tracepoint_valid_at): "msg" now a
+	std::string*.
+
 2018-02-23  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* gdbtypes.h (sect_offset): Change type to uint64_t.
diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
index 693d7e3..2ff0f4d 100644
--- a/gdb/arch-utils.c
+++ b/gdb/arch-utils.c
@@ -813,12 +813,12 @@ default_has_shared_address_space (struct gdbarch *gdbarch)
 
 int
 default_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr,
-				  char **msg)
+				  std::string *msg)
 {
   /* We don't know if maybe the target has some way to do fast
      tracepoints that doesn't need gdbarch, so always say yes.  */
   if (msg)
-    *msg = NULL;
+    msg->clear ();
   return 1;
 }
 
diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h
index b51a4ec..3407a16 100644
--- a/gdb/arch-utils.h
+++ b/gdb/arch-utils.h
@@ -202,7 +202,7 @@ extern struct gdbarch *get_current_arch (void);
 extern int default_has_shared_address_space (struct gdbarch *);
 
 extern int default_fast_tracepoint_valid_at (struct gdbarch *gdbarch,
-					     CORE_ADDR addr, char **msg);
+					     CORE_ADDR addr, std::string *msg);
 
 extern const gdb_byte *default_breakpoint_from_pc (struct gdbarch *gdbarch,
 						   CORE_ADDR *pcptr,
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 91ecca6..c56084c 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -9177,10 +9177,6 @@ static void
 check_fast_tracepoint_sals (struct gdbarch *gdbarch,
 			    gdb::array_view<const symtab_and_line> sals)
 {
-  int rslt;
-  char *msg;
-  struct cleanup *old_chain;
-
   for (const auto &sal : sals)
     {
       struct gdbarch *sarch;
@@ -9190,14 +9186,10 @@ check_fast_tracepoint_sals (struct gdbarch *gdbarch,
 	 associated with SAL.  */
       if (sarch == NULL)
 	sarch = gdbarch;
-      rslt = gdbarch_fast_tracepoint_valid_at (sarch, sal.pc, &msg);
-      old_chain = make_cleanup (xfree, msg);
-
-      if (!rslt)
+      std::string msg;
+      if (!gdbarch_fast_tracepoint_valid_at (sarch, sal.pc, &msg))
 	error (_("May not have a fast tracepoint at %s%s"),
-	       paddress (sarch, sal.pc), (msg ? msg : ""));
-
-      do_cleanups (old_chain);
+	       paddress (sarch, sal.pc), msg.c_str ());
     }
 }
 
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 62cb9a5..b8703e5 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -4650,7 +4650,7 @@ set_gdbarch_has_shared_address_space (struct gdbarch *gdbarch,
 }
 
 int
-gdbarch_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr, char **msg)
+gdbarch_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr, std::string *msg)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->fast_tracepoint_valid_at != NULL);
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index 30c2bf3..5cb131d 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -1366,8 +1366,8 @@ extern void set_gdbarch_has_shared_address_space (struct gdbarch *gdbarch, gdbar
 
 /* True if a fast tracepoint can be set at an address. */
 
-typedef int (gdbarch_fast_tracepoint_valid_at_ftype) (struct gdbarch *gdbarch, CORE_ADDR addr, char **msg);
-extern int gdbarch_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr, char **msg);
+typedef int (gdbarch_fast_tracepoint_valid_at_ftype) (struct gdbarch *gdbarch, CORE_ADDR addr, std::string *msg);
+extern int gdbarch_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr, std::string *msg);
 extern void set_gdbarch_fast_tracepoint_valid_at (struct gdbarch *gdbarch, gdbarch_fast_tracepoint_valid_at_ftype *fast_tracepoint_valid_at);
 
 /* Guess register state based on tracepoint location.  Used for tracepoints
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 10a2aa9..33dfa6b 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -1045,7 +1045,7 @@ v;int;has_global_breakpoints;;;0;0;;0
 m;int;has_shared_address_space;void;;;default_has_shared_address_space;;0
 
 # True if a fast tracepoint can be set at an address.
-m;int;fast_tracepoint_valid_at;CORE_ADDR addr, char **msg;addr, msg;;default_fast_tracepoint_valid_at;;0
+m;int;fast_tracepoint_valid_at;CORE_ADDR addr, std::string *msg;addr, msg;;default_fast_tracepoint_valid_at;;0
 
 # Guess register state based on tracepoint location.  Used for tracepoints
 # where no registers have been collected, but there's only one location,
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 6b59278..60dc801 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -8111,7 +8111,7 @@ static const int i386_record_regmap[] =
 
 static int
 i386_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr,
-			       char **msg)
+			       std::string *msg)
 {
   int len, jumplen;
 
@@ -8144,15 +8144,15 @@ i386_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr,
       /* Return a bit of target-specific detail to add to the caller's
 	 generic failure message.  */
       if (msg)
-	*msg = xstrprintf (_("; instruction is only %d bytes long, "
-			     "need at least %d bytes for the jump"),
-			   len, jumplen);
+	*msg = string_printf (_("; instruction is only %d bytes long, "
+				"need at least %d bytes for the jump"),
+			      len, jumplen);
       return 0;
     }
   else
     {
       if (msg)
-	*msg = NULL;
+	msg->clear ();
       return 1;
     }
 }