gdb: Introduce new language field la_is_string_type_p

This commit is preparation work for the next commit, and by itself
makes no user visible change to GDB.  I've split this work into a
separate commit in order to make code review easier.

This commit adds a new field 'la_is_string_type_p' to the language
struct, this predicate will return true if a type is a string type for
the given language.

Some languages already have a "is this a string" predicate that I was
able to reuse, while for other languages I've had to add a new
predicate.  In this case I took inspiration from the value printing
code for that language - what different conditions would result in
printing something as a string.

A default "is this a string" method has also been added that looks for
TYPE_CODE_STRING, this is the fallback I've used for a couple of
languages.

In this commit I add the new field and initialise it for each
language, however at this stage the new field is never used.

gdb/ChangeLog:

	* ada-lang.c (ada_language_defn): Initialise new field.
	* c-lang.c (c_is_string_type_p): New function.
	(c_language_defn): Initialise new field.
	(cplus_language_defn): Initialise new field.
	(asm_language_defn): Initialise new field.
	(minimal_language_defn): Initialise new field.
	* c-lang.h (c_is_string_type_p): Declare new function.
	* d-lang.c (d_language_defn): Initialise new field.
	* f-lang.c (f_is_string_type_p): New function.
	(f_language_defn): Initialise new field.
	* go-lang.c (go_is_string_type_p): New function.
	(go_language_defn): Initialise new field.
	* language.c (default_is_string_type_p): New function.
	(unknown_language_defn): Initialise new field.
	(auto_language_defn): Initialise new field.
	* language.h (struct language_defn) <la_is_string_type_p>: New
	member variable.
	(default_is_string_type_p): Declare new function.
	* m2-lang.c (m2_language_defn): Initialise new field.
	* objc-lang.c (objc_language_defn): Initialise new field.
	* opencl-lang.c (opencl_language_defn): Initialise new field.
	* p-lang.c (pascal_is_string_type_p): New function.
	(pascal_language_defn): Initialise new field.
	* rust-lang.c (rust_is_string_type_p): New function.
	(rust_language_defn): Initialise new field.

1 files changed, 11 insertions, 0 deletions

diff --git a/gdb/go-lang.c b/gdb/go-lang.c
index b8617cb..6473468 100644
--- a/gdb/go-lang.c
+++ b/gdb/go-lang.c
@@ -130,6 +130,16 @@ go_classify_struct_type (struct type *type)
   return GO_TYPE_NONE;
 }
 
+/* Return true if TYPE is a string.  */
+
+static bool
+go_is_string_type_p (struct type *type)
+{
+  type = check_typedef (type);
+  return (TYPE_CODE (type) == TYPE_CODE_STRUCT
+	  && go_classify_struct_type (type) == GO_TYPE_STRING);
+}
+
 /* Subroutine of unpack_mangled_go_symbol to simplify it.
    Given "[foo.]bar.baz", store "bar" in *PACKAGEP and "baz" in *OBJECTP.
    We stomp on the last '.' to nul-terminate "bar".
@@ -612,6 +622,7 @@ extern const struct language_defn go_language_defn =
   &default_varobj_ops,
   NULL,
   NULL,
+  go_is_string_type_p,
   "{...}"			/* la_struct_too_deep_ellipsis */
 };