Avoid manual memory management of argv arrays in gdb/compile

This changes gdb/compile to use gdb_argv directly, rather than
manually managing the arrays itself.  A few new helpers are added to
gdb_argv.

gdb/ChangeLog
2020-09-23  Tom Tromey  <tom@tromey.com>

	* utils.h (class gdb_argv): Add move operators.
	<append>: New methods.
	* compile/compile.c (build_argc_argv): Remove.
	(compile_args_argc): Remove.
	(compile_args_argv): Change type.
	(set_compile_args): Simplify.
	(append_args): Remove.
	(filter_args): Remove argcp parameter.
	(get_args): Return gdb_argv.  Simplify.
	(compile_to_object): Update.

1 files changed, 43 insertions, 0 deletions

diff --git a/gdb/utils.h b/gdb/utils.h
index 9a235b9..6948908 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -165,6 +165,20 @@ public:
   gdb_argv (const gdb_argv &) = delete;
   gdb_argv &operator= (const gdb_argv &) = delete;
 
+  gdb_argv &operator= (gdb_argv &&other)
+  {
+    freeargv (m_argv);
+    m_argv = other.m_argv;
+    other.m_argv = nullptr;
+    return *this;
+  }
+
+  gdb_argv (gdb_argv &&other)
+  {
+    m_argv = other.m_argv;
+    other.m_argv = nullptr;
+  }
+
   ~gdb_argv ()
   {
     freeargv (m_argv);
@@ -218,6 +232,35 @@ public:
     return gdb::array_view<char *> (this->get (), this->count ());
   }
 
+  /* Append arguments to this array.  */
+  void append (gdb_argv &&other)
+  {
+    int size = count ();
+    int argc = other.count ();
+    m_argv = XRESIZEVEC (char *, m_argv, (size + argc + 1));
+
+    for (int argi = 0; argi < argc; argi++)
+      {
+	/* Transfer ownership of the string.  */
+	m_argv[size++] = other.m_argv[argi];
+	/* Ensure that destruction of OTHER works correctly.  */
+	other.m_argv[argi] = nullptr;
+      }
+    m_argv[size] = nullptr;
+  }
+
+  /* Append arguments to this array.  */
+  void append (const gdb_argv &other)
+  {
+    int size = count ();
+    int argc = other.count ();
+    m_argv = XRESIZEVEC (char *, m_argv, (size + argc + 1));
+
+    for (int argi = 0; argi < argc; argi++)
+      m_argv[size++] = xstrdup (other.m_argv[argi]);
+    m_argv[size] = nullptr;
+  }
+
   /* The iterator type.  */
 
   typedef char **iterator;