Use standard diff separator for regression.diffs

Instead of ======..., use the standard separator for a multi-file
diff, which is, per POSIX,

    "diff %s %s %s\n", <diff_options>, <filename1>, <filename2>

This makes regression.diffs behave more like a proper diff file, for
use with other tools.  And it shows the diff options used, for
clarity.

Discussion: https://www.postgresql.org/message-id/70440c81-37bb-76dd-e48b-b5a9550d5613@2ndquadrant.com

diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index a4caa228e28ea06d46744dc821982ae71473c8f4..10111ebfb913941518504b3b3700ce99477f7001 100644 (file)
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -1454,20 +1454,23 @@ results_differ(const char *testname, const char *resultsfile, const char *defaul
     * Use the best comparison file to generate the "pretty" diff, which we
     * append to the diffs summary file.
     */
-   snprintf(cmd, sizeof(cmd),
-            "diff %s \"%s\" \"%s\" >> \"%s\"",
-            pretty_diff_opts, best_expect_file, resultsfile, difffilename);
-   run_diff(cmd, difffilename);
 
-   /* And append a separator */
+   /* Write diff header */
    difffile = fopen(difffilename, "a");
    if (difffile)
    {
        fprintf(difffile,
-               "\n======================================================================\n\n");
+               "diff %s %s %s\n",
+               pretty_diff_opts, best_expect_file, resultsfile);
        fclose(difffile);
    }
 
+   /* Run diff */
+   snprintf(cmd, sizeof(cmd),
+            "diff %s \"%s\" \"%s\" >> \"%s\"",
+            pretty_diff_opts, best_expect_file, resultsfile, difffilename);
+   run_diff(cmd, difffilename);
+
    unlink(diff);
    return true;
 }