master ad011fd3ac: Make STRING_SET_MULTIBYTE an inline function

[Stefan Monnier]

branch: master
commit ad011fd3accd97f5ab96dd7459ee8ef9f6ab4090
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Commit: Stefan Monnier <monnier@iro.umontreal.ca>

    Make STRING_SET_MULTIBYTE an inline function
    
    * src/lisp.h (STRING_SET_MULTIBYTE): Make it into a function.
    
    * src/composite.c (Fcomposition_get_gstring):
    Prefer `make_multibyte_string` over Fconcat+STRING_SET_MULTIBYTE.
---
 src/composite.c | 10 ++++++----
 src/lisp.h      | 14 +++++++-------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/composite.c b/src/composite.c
index 4d69702171..552214ae84 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -1871,7 +1871,8 @@ should be ignored.  */)
   else
     {
       CHECK_STRING (string);
-      validate_subarray (string, from, to, SCHARS (string), &frompos, &topos);
+      ptrdiff_t chars = SCHARS (string);
+      validate_subarray (string, from, to, chars, &frompos, &topos);
       if (! STRING_MULTIBYTE (string))
        {
          ptrdiff_t i;
@@ -1881,9 +1882,10 @@ should be ignored.  */)
              error ("Attempt to shape unibyte text");
          /* STRING is a pure-ASCII string, so we can convert it (or,
             rather, its copy) to multibyte and use that thereafter.  */
-         Lisp_Object string_copy = Fconcat (1, &string);
-         STRING_SET_MULTIBYTE (string_copy);
-         string = string_copy;
+         /* FIXME: Not clear why we need to do that: AFAICT the rest of
+             the code should work on an ASCII-only unibyte string just
+             as well (bug#56347).  */
+         string = make_multibyte_string (SDATA (string), chars, chars);
        }
       frombyte = string_char_to_byte (string, frompos);
     }
diff --git a/src/lisp.h b/src/lisp.h
index 5ffc2bb038..dc496cc165 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1640,13 +1640,13 @@ STRING_MULTIBYTE (Lisp_Object str)
 
 /* Mark STR as a multibyte string.  Assure that STR contains only
    ASCII characters in advance.  */
-#define STRING_SET_MULTIBYTE(STR)                      \
-  do {                                                 \
-    if (XSTRING (STR)->u.s.size == 0)                  \
-      (STR) = empty_multibyte_string;                  \
-    else                                               \
-      XSTRING (STR)->u.s.size_byte = XSTRING (STR)->u.s.size; \
-  } while (false)
+INLINE void
+STRING_SET_MULTIBYTE (Lisp_Object str)
+{
+  /* The 0-length strings are unique&shared so we can't modify them.  */
+  eassert (XSTRING (str)->u.s.size > 0);
+  XSTRING (str)->u.s.size_byte = XSTRING (str)->u.s.size;
+}
 
 /* Convenience functions for dealing with Lisp strings.  */