Fix rails#54805.

When using postgres adapter and the `structure_load_flags` options, the
extra flags were appended instead of prepended to the default ones,
causing the `psql` command to ignore some of the extra flags.

Now, the default arguments `args` are appended to the `extra_flags`
instead of the opposite.

Example of `extra_flags` that were ignored by postgres:

    ActiveRecord::Tasks::DatabaseTasks.structure_load_flags = ['-c', 'SET my_extension.level=off;'].freeze

Now, they will be taken into account.

Author: AliceLoeser

activerecord/CHANGELOG.md

@@ -1,3 +1,11 @@
+*   Prepend `extra_flags` in postgres' `structure_load`
+
+    When specifying `structure_load_flags` with a postgres adapter, the flags
+    were appended to the default flags, instead of prepended.
+    This caused issues with flags not being taken into account by postgres.
+
+    *Alice Loeser*
+
 *   Allow bypassing primary key/constraint addition in `implicit_order_column`
 
     When specifying multiple columns in an array for `implicit_order_column`, adding

activerecord/lib/active_record/tasks/postgresql_database_tasks.rb

@@ -78,8 +78,9 @@ def structure_dump(filename, extra_flags)
       end
 
       def structure_load(filename, extra_flags)
-        args = ["--set", ON_ERROR_STOP_1, "--quiet", "--no-psqlrc", "--output", File::NULL, "--file", filename]
+        args = ["--set", ON_ERROR_STOP_1, "--quiet", "--no-psqlrc", "--output", File::NULL]
         args.concat(Array(extra_flags)) if extra_flags
+        args.concat(["--file", filename])
         args << db_config.database
         run_cmd("psql", args, "loading")
       end

activerecord/test/cases/adapters/postgresql/postgresql_rake_test.rb

@@ -517,7 +517,7 @@ def test_structure_load
 
     def test_structure_load_with_extra_flags
       filename = "awesome-file.sql"
-      expected_command = [{}, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--file", filename, "--noop", @configuration["database"]]
+      expected_command = [{}, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--noop", "--file", filename, @configuration["database"]]
 
       assert_called_with(Kernel, :system, expected_command, returns: true) do
         with_structure_load_flags(["--noop"]) do
@@ -529,7 +529,7 @@ def test_structure_load_with_extra_flags
     def test_structure_load_with_env
       filename = "awesome-file.sql"
       expected_env = { "PGHOST" => "my.server.tld", "PGPORT" => "2345", "PGUSER" => "jane", "PGPASSWORD" => "s3cr3t" }
-      expected_command = [expected_env, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--file", filename, "--noop", @configuration["database"]]
+      expected_command = [expected_env, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--noop", "--file", filename, @configuration["database"]]
 
       assert_called_with(Kernel, :system, expected_command, returns: true) do
         with_structure_load_flags(["--noop"]) do
@@ -544,7 +544,7 @@ def test_structure_load_with_env
     def test_structure_load_with_ssl_env
       filename = "awesome-file.sql"
       expected_env = { "PGSSLMODE" => "verify-full", "PGSSLCERT" => "client.crt", "PGSSLKEY" => "client.key", "PGSSLROOTCERT" => "root.crt" }
-      expected_command = [expected_env, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--file", filename, "--noop", @configuration["database"]]
+      expected_command = [expected_env, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--noop", "--file", filename, @configuration["database"]]
 
       assert_called_with(Kernel, :system, expected_command, returns: true) do
         with_structure_load_flags(["--noop"]) do
@@ -569,7 +569,7 @@ def test_structure_load_with_hash_extra_flags_for_a_different_driver
 
     def test_structure_load_with_hash_extra_flags_for_the_correct_driver
       filename = "awesome-file.sql"
-      expected_command = [{}, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--file", filename, "--noop", @configuration["database"]]
+      expected_command = [{}, "psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--output", File::NULL, "--noop", "--file", filename, @configuration["database"]]
 
       assert_called_with(Kernel, :system, expected_command, returns: true) do
         with_structure_load_flags({ postgresql: ["--noop"] }) do