Merge branch 'topic/gnatcheck/implicit_rule_file' into 'master'

Disable implicit LKQL rule file fetching from the working directory

Closes #457

See merge request eng/libadalang/langkit-query-language!428

Author: HugoGGuerrier

lkql_checker/doc/gnatcheck_rm/using_gnatcheck.rst

@@ -442,11 +442,11 @@ You can configure GNATcheck rules using an LKQL file, provided through the
 ``--rule-file`` command-line option or implicitly fetched by GNATcheck (as
 described in the following paragraph).
 
-By default, GNATcheck will look for a ``rules.lkql`` file in the current working
-directory or besides the specified project file if any. If there is one and
-no other rule configuration has been provided (through an LKQL rule file, or
-through the rule options), GNATcheck will load it as the LKQL rule options
-file, as if it was provided through the ``--rule-file`` option.
+By default, GNATcheck will look for a ``rules.lkql`` file besides the specified
+project file if any. If there is one and no other rule configuration has been
+provided (through an LKQL rule file, or through the rule options), GNATcheck
+will load it as the LKQL rule options file, as if it was provided through the
+``--rule-file`` option.
 
 .. note::
 

lkql_checker/src/gnatcheck_main.adb

@@ -511,7 +511,7 @@ begin
    end if;
 
    --  Get the default LKQL rule file if none has been specified
-   if Is_Rule_Options_Empty then
+   if Is_Rule_Options_Empty and then Gnatcheck_Prj.Is_Specified then
       declare
          Def_LKQL : constant String := Default_LKQL_Rule_Options_File;
       begin

testsuite/tests/gnatcheck/lkql_rules_config/implicit_config_file/test.out

@@ -1,7 +1,9 @@
 Without project file
 ====================
 
-main.adb:3:04: rule violation: goto statement
+gnatcheck: error: no rule to check specified
+try "gnatcheck --help" for more information.
+>>>program returned status code 2
 
 With project file
 =================