Recommend wrappers of PG_DETOAST_DATUM_PACKED().

When commit 3e23b68dac006e8deb0afa327e855258df8de064 introduced
single-byte varlena headers, its fmgr.h changes presented
PG_GETARG_TEXT_PP() and PG_GETARG_TEXT_P() as equals.  Its postgres.h
changes presented PG_DETOAST_DATUM_PACKED() and VARDATA_ANY() as the
exceptional case.  Now, instead, firmly recommend PG_GETARG_TEXT_PP()
over PG_GETARG_TEXT_P(); likewise for other ...PP() macros.  This shaves
cycles and invites consistency of style.

1 files changed, 19 insertions, 13 deletions

diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml
index 255bfddad79..94a7ad747da 100644
--- a/doc/src/sgml/xfunc.sgml
+++ b/doc/src/sgml/xfunc.sgml
@@ -2388,18 +2388,23 @@ PG_FUNCTION_INFO_V1(copytext);
 Datum
 copytext(PG_FUNCTION_ARGS)
 {
-    text     *t = PG_GETARG_TEXT_P(0);
+    text     *t = PG_GETARG_TEXT_PP(0);
+
     /*
-     * VARSIZE is the total size of the struct in bytes.
+     * VARSIZE_ANY_EXHDR is the size of the struct in bytes, minus the
+     * VARHDRSZ or VARHDRSZ_SHORT of its header.  Construct the copy with a
+     * full-length header.
      */
-    text     *new_t = (text *) palloc(VARSIZE(t));
-    SET_VARSIZE(new_t, VARSIZE(t));
+    text     *new_t = (text *) palloc(VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
+    SET_VARSIZE(new_t, VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
+
     /*
-     * VARDATA is a pointer to the data region of the struct.
+     * VARDATA is a pointer to the data region of the new struct.  The source
+     * could be a short datum, so retrieve its data through VARDATA_ANY.
      */
     memcpy((void *) VARDATA(new_t), /* destination */
-           (void *) VARDATA(t),     /* source */
-           VARSIZE(t) - VARHDRSZ);  /* how many bytes */
+           (void *) VARDATA_ANY(t), /* source */
+           VARSIZE_ANY_EXHDR(t));   /* how many bytes */
     PG_RETURN_TEXT_P(new_t);
 }
 
@@ -2408,15 +2413,16 @@ PG_FUNCTION_INFO_V1(concat_text);
 Datum
 concat_text(PG_FUNCTION_ARGS)
 {
-    text  *arg1 = PG_GETARG_TEXT_P(0);
-    text  *arg2 = PG_GETARG_TEXT_P(1);
-    int32 new_text_size = VARSIZE(arg1) + VARSIZE(arg2) - VARHDRSZ;
+    text  *arg1 = PG_GETARG_TEXT_PP(0);
+    text  *arg2 = PG_GETARG_TEXT_PP(1);
+    int32 arg1_size = VARSIZE_ANY_EXHDR(arg1);
+    int32 arg2_size = VARSIZE_ANY_EXHDR(arg2);
+    int32 new_text_size = arg1_size + arg2_size + VARHDRSZ;
     text *new_text = (text *) palloc(new_text_size);
 
     SET_VARSIZE(new_text, new_text_size);
-    memcpy(VARDATA(new_text), VARDATA(arg1), VARSIZE(arg1) - VARHDRSZ);
-    memcpy(VARDATA(new_text) + (VARSIZE(arg1) - VARHDRSZ),
-           VARDATA(arg2), VARSIZE(arg2) - VARHDRSZ);
+    memcpy(VARDATA(new_text), VARDATA_ANY(arg1), arg1_size);
+    memcpy(VARDATA(new_text) + arg1_size, VARDATA_ANY(arg2), arg2_size);
     PG_RETURN_TEXT_P(new_text);
 }
 ]]>