Add default per-path stds

Unless --no-config is used, add default per-path overrides for stds
if not set already:

files["**/spec/**/*_spec.lua"].std = "+busted"
files["**/test/**/*_spec.lua"].std = "+busted"
files["**/tests/**/*_spec.lua"].std = "+busted"
files["**/*.rockspec"].std = "+rockspec"
files[**/*.luacheckrc"].std = "+luacheckrc"

.busted

@@ -0,0 +1,5 @@
+return {
+   _all = {
+      ["exclude-pattern"] = "sample_spec"
+   }
+}

.luacheckrc

@@ -1,7 +1,5 @@
 std = "min"
 cache = true
-include_files = {"src", "spec/*.lua", "scripts/*.lua"}
+include_files = {"src", "spec/*.lua", "scripts/*.lua", "*.rockspec", "*.luacheckrc"}
 
-files["spec/*_spec.lua"].std = "+busted"
-files["src/luacheck/argparse.lua"].max_line_length = 140
 files["src/luacheck/unicode_printability_boundaries.lua"].max_line_length = false

luacheck-dev-1.rockspec

@@ -6,7 +6,9 @@ source = {
 description = {
    summary = "A static analyzer and a linter for Lua",
    detailed = [[
-Luacheck is a command-line tool for linting and static analysis of Lua code. It is able to spot usage of undefined global variables, unused local variables and a few other typical problems within Lua programs.
+Luacheck is a command-line tool for linting and static analysis of Lua code.
+It is able to spot usage of undefined global variables, unused local variables and
+a few other typical problems within Lua programs.
 ]],
    homepage = "https://github.com/mpeterv/luacheck",
    license = "MIT"

spec/cli_spec.lua

@@ -1210,6 +1210,71 @@ Total: 4 warnings / 0 errors in 2 files
 ]], get_output "spec/samples/bad_code.lua spec/samples/unused_code.lua --config=spec/configs/override_config.luacheckrc")
          end)
 
+         it("adds per-file overrides with default stds", function()
+            assert.equal(([[
+Checking .luacheckrc                              3 warnings
+
+    .luacheckrc:14:6: accessing undefined variable 'it'
+    .luacheckrc:14:10: accessing undefined variable 'version'
+    .luacheckrc:14:25: accessing undefined variable 'newproxy'
+
+Checking default_stds-scm-1.rockspec              3 warnings
+
+    default_stds-scm-1.rockspec:13:1: accessing undefined variable 'it'
+    default_stds-scm-1.rockspec:13:21: accessing undefined variable 'newproxy'
+    default_stds-scm-1.rockspec:13:37: accessing undefined variable 'new_globals'
+
+Checking nested/spec/sample_spec.lua              3 warnings
+
+    nested/spec/sample_spec.lua:1:39: accessing undefined variable 'newproxy'
+    nested/spec/sample_spec.lua:1:55: accessing undefined variable 'version'
+    nested/spec/sample_spec.lua:1:64: accessing undefined variable 'read_globals'
+
+Checking normal_file.lua                          4 warnings
+
+    normal_file.lua:1:1: accessing undefined variable 'it'
+    normal_file.lua:1:29: accessing undefined variable 'newproxy'
+    normal_file.lua:1:45: accessing undefined variable 'version'
+    normal_file.lua:1:54: accessing undefined variable 'read_globals'
+
+Checking sample_spec.lua                          4 warnings
+
+    sample_spec.lua:1:1: accessing undefined variable 'it'
+    sample_spec.lua:1:28: accessing undefined variable 'newproxy'
+    sample_spec.lua:1:44: accessing undefined variable 'version'
+    sample_spec.lua:1:53: accessing undefined variable 'read_globals'
+
+Checking test/nested_normal_file.lua              4 warnings
+
+    test/nested_normal_file.lua:1:1: accessing undefined variable 'it'
+    test/nested_normal_file.lua:1:47: accessing undefined variable 'newproxy'
+    test/nested_normal_file.lua:1:63: accessing undefined variable 'version'
+    test/nested_normal_file.lua:1:72: accessing undefined variable 'read_globals'
+
+Checking test/sample_spec.lua                     5 warnings
+
+    test/sample_spec.lua:1:1: accessing undefined variable 'it'
+    test/sample_spec.lua:1:37: accessing undefined variable 'newproxy'
+    test/sample_spec.lua:1:47: accessing undefined variable 'math'
+    test/sample_spec.lua:1:53: accessing undefined variable 'version'
+    test/sample_spec.lua:1:62: accessing undefined variable 'read_globals'
+
+Checking tests/nested/sample_spec.lua             3 warnings
+
+    tests/nested/sample_spec.lua:1:44: accessing undefined variable 'newproxy'
+    tests/nested/sample_spec.lua:1:60: accessing undefined variable 'version'
+    tests/nested/sample_spec.lua:1:69: accessing undefined variable 'read_globals'
+
+Checking tests/sample_spec.lua                    3 warnings
+
+    tests/sample_spec.lua:1:17: accessing undefined variable 'newproxy'
+    tests/sample_spec.lua:1:33: accessing undefined variable 'version'
+    tests/sample_spec.lua:1:42: accessing undefined variable 'read_globals'
+
+Total: 32 warnings / 0 errors in 9 files
+]]):gsub("([a-z])/", "%1" .. package.config:sub(1, 1)), get_output(". --include-files .", "spec/projects/default_stds/"))
+         end)
+
          it("uses new filename when selecting per-file overrides", function()
             assert.equal([[
 Checking spec/samples/unused_code.lua             OK

spec/projects/default_stds/.luacheckrc

@@ -0,0 +1,14 @@
+std = "min"
+
+files["**/test/**/*_spec.lua"] = {
+   std = "none"
+}
+
+local shared_options = {ignore = {"ignored"}}
+
+files["**/spec/**/*_spec.lua"] = shared_options
+files["normal_file.lua"] = shared_options
+
+local function sink() end
+
+sink(it, version, math, newproxy)

spec/projects/default_stds/default_stds-scm-1.rockspec

@@ -0,0 +1,13 @@
+package = "default_stds"
+version = "scm-1"
+source = {
+   url = "https://example.com"
+}
+description = {
+   summary = "example",
+   detailed = "example",
+   homepage = "https://example.com",
+   license = "MIT"
+}
+dependencies = {}
+it("is a rockspec")(newproxy, math, new_globals)

spec/projects/default_stds/nested/spec/sample_spec.lua

@@ -0,0 +1,2 @@
+it("is a test in a nested directory")(newproxy, math, version, read_globals)
+ignored()

spec/projects/default_stds/normal_file.lua

@@ -0,0 +1,2 @@
+it("is just a normal file")(newproxy, math, version, read_globals)
+ignored()

spec/projects/default_stds/sample_spec.lua

@@ -0,0 +1 @@
+it("is not really a test")(newproxy, math, version, read_globals)

spec/projects/default_stds/test/nested_normal_file.lua

@@ -0,0 +1 @@
+it("is a normal file in a  nested directory")(newproxy, math, version, read_globals)

spec/projects/default_stds/test/sample_spec.lua

@@ -0,0 +1 @@
+it("is a test in a test directory")(newproxy, math, version, read_globals)

spec/projects/default_stds/tests/nested/sample_spec.lua

@@ -0,0 +1 @@
+it("is a test in a very nested directory")(newproxy, math, version, read_globals)

spec/projects/default_stds/tests/sample_spec.lua

@@ -0,0 +1 @@
+it("is a test")(newproxy, math, version, read_globals)

spec/samples/sample.rockspec

@@ -2,6 +2,7 @@ build = {
    type = "builtin",
    modules = {
       good = "spec/samples/good_code.lua",
-      bad = "spec/samples/bad_code.lua"
+      bad = "spec/samples/bad_code.lua",
+      not_even_a_module = some_global
    }
 }

src/luacheck/config.lua

@@ -203,6 +203,35 @@ local function remove_env_mt(env, special_values)
    utils.update(env, special_values)
 end
 
+local function set_default_std(files, pattern, std)
+   -- Avoid mutating option tables, they may be shared between different patterns.
+   local pattern_opts = {std = std}
+
+   if files[pattern] then
+      pattern_opts = utils.update(pattern_opts, files[pattern])
+   end
+
+   files[pattern] = pattern_opts
+end
+
+local function add_default_path_options(opts)
+   local files = {}
+
+   if opts.files then
+      files = utils.update(files, opts.files)
+   end
+
+   opts.files = files
+   set_default_std(files, "**/spec/**/*_spec.lua", "+busted")
+   set_default_std(files, "**/test/**/*_spec.lua", "+busted")
+   set_default_std(files, "**/tests/**/*_spec.lua", "+busted")
+   set_default_std(files, "**/*.rockspec", "+rockspec")
+   set_default_std(files, "**/*.luacheckrc", "+luacheckrc")
+end
+
+local fallback_config = {options = {}}
+add_default_path_options(fallback_config.options)
+
 -- Loads config from a file, if possible.
 -- `path` and `global_path` can be nil (will use default), false (will disable loading), or a string.
 -- Doesn't validate the config.
@@ -214,7 +243,7 @@ function config.load_config(path, global_path)
       if anchor_dir then
          return nil, anchor_dir
       else
-         return {options = {}}
+         return fallback_config
       end
    end
 
@@ -234,7 +263,7 @@ function config.load_config(path, global_path)
    end
 
    remove_env_mt(env, special_values)
-
+   add_default_path_options(env)
    return {options = env, config_path = config_path, anchor_dir = anchor_dir}
 end