Fix #1128 - Add g:ale_linters_explicit for only enabling linters explicitly

5 files changed, 119 insertions, 15 deletions

diff --git a/autoload/ale/linter.vim b/autoload/ale/linter.vim
index c6667d95..e8f30fff 100644
--- a/autoload/ale/linter.vim
+++ b/autoload/ale/linter.vim
@@ -21,6 +21,8 @@ let s:default_ale_linter_aliases = {
 "
 " Only cargo is enabled for Rust by default.
 " rpmlint is disabled by default because it can result in code execution.
+"
+" NOTE: Update the g:ale_linters documentation when modifying this.
 let s:default_ale_linters = {
 \   'csh': ['shell'],
 \   'go': ['gofmt', 'golint', 'go vet'],
@@ -308,11 +310,26 @@ function! s:GetLinterNames(original_filetype) abort
         return l:buffer_ale_linters
     endif
 
-    for l:dict in [l:buffer_ale_linters, g:ale_linters, s:default_ale_linters]
-        if has_key(l:dict, a:original_filetype)
-            return l:dict[a:original_filetype]
-        endif
-    endfor
+    " Try to get a buffer-local setting for the filetype
+    if has_key(l:buffer_ale_linters, a:original_filetype)
+        return l:buffer_ale_linters[a:original_filetype]
+    endif
+
+    " Try to get a global setting for the filetype
+    if has_key(g:ale_linters, a:original_filetype)
+        return g:ale_linters[a:original_filetype]
+    endif
+
+    " If the user has configured ALE to only enable linters explicitly, then
+    " don't enable any linters by default.
+    if g:ale_linters_explicit
+        return []
+    endif
+
+    " Try to get a default setting for the filetype
+    if has_key(s:default_ale_linters, a:original_filetype)
+        return s:default_ale_linters[a:original_filetype]
+    endif
 
     return 'all'
 endfunction
diff --git a/doc/ale.txt b/doc/ale.txt
index b653e5c4..cd6a3a0d 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -946,23 +946,25 @@ g:ale_linters                                                   *g:ale_linters*
   Type: |Dictionary|
   Default: `{}`
 
-  The |g:ale_linters| option sets a |Dictionary| mapping a filetype
-  to a |List| of linter programs to be run when checking particular filetypes.
-  Only the filetypes specified in the dictionary will be limited in terms
-  of which linters will be run.
+  The |g:ale_linters| option sets a |Dictionary| mapping a filetype to a
+  |List| of linter programs to be run when checking particular filetypes.
 
   This |Dictionary| will be merged with a default dictionary containing the
   following values: >
 
   {
   \   'csh': ['shell'],
+  \   'go': ['gofmt', 'golint', 'go vet'],
+  \   'help': [],
+  \   'python': ['flake8', 'mypy', 'pylint'],
   \   'rust': ['cargo'],
+  \   'spec': [],
   \   'text': [],
   \   'zsh': ['shell'],
   \}
 <
   This option can be used to enable only a particular set of linters for a
-  file. For example, you can enable only 'eslint' for JavaScript files: >
+  file. For example, you can enable only `eslint` for JavaScript files: >
 
   let g:ale_linters = {'javascript': ['eslint']}
 <
@@ -971,14 +973,15 @@ g:ale_linters                                                   *g:ale_linters*
 
   let g:ale_linters = {'javascript': []}
 <
-  All linters available for a given filetype can be enabled by using the
-  string `'all'`: >
+  All linters will be run for unspecified filetypes. All available linters can
+  be enabled explicitly for a given filetype by passing the string `'all'`,
+  instead of a List. >
 
   let g:ale_linters = {'c': 'all'}
 <
   Linters can be configured in each buffer with buffer-local variables. ALE
   will first look for linters for filetypes in the `b:ale_linters` variable,
-  then `g:ale_linters`, and then a default Dictionary.
+  then `g:ale_linters`, and then the default Dictionary mentioned above.
 
   `b:ale_linters` can be set to a List, or the string `'all'`. When linters
   for two different filetypes share the same name, the first linter loaded
@@ -994,6 +997,19 @@ g:ale_linters                                                   *g:ale_linters*
   " Explicitly enable all available linters for the filetype.
   let b:ale_linters = 'all'
 <
+  ALE can be configured to disable all linters unless otherwise specified with
+  `g:ale_enabled` or `b:ale_enabled` with the option |g:ale_linters_explicit|.
+
+
+g:ale_linters_explicit                                 *g:ale_linters_explicit*
+
+  Type: |Number|
+  Default: `0`
+
+  When set to `1`, only the linters from |g:ale_linters| and |b:ale_linters|
+  will be enabled. The default behavior for ALE is to enable as many linters
+  as possible, unless otherwise specified.
+
 
 g:ale_loclist_msg_format                             *g:ale_loclist_msg_format*
 
diff --git a/plugin/ale.vim b/plugin/ale.vim
index 11df5204..31c3377e 100644
--- a/plugin/ale.vim
+++ b/plugin/ale.vim
@@ -68,7 +68,9 @@ let g:ale_filetype_blacklist = [
 \]
 
 " This Dictionary configures which linters are enabled for which languages.
-let g:ale_linters = get(g:, 'ale_linters', {})
+call ale#Set('linters', {})
+" This option can be changed to only enable explicitly selected linters.
+call ale#Set('linters_explicit', 0)
 
 " This Dictionary configures which functions will be used for fixing problems.
 let g:ale_fixers = get(g:, 'ale_fixers', {})
diff --git a/test/test_filetype_linter_defaults.vader b/test/test_filetype_linter_defaults.vader
new file mode 100644
index 00000000..ea4a05fb
--- /dev/null
+++ b/test/test_filetype_linter_defaults.vader
@@ -0,0 +1,68 @@
+Before:
+  Save g:ale_linters
+  Save g:ale_linters_explicit
+
+  let g:ale_linters_explicit = 0
+  let g:ale_linters = {}
+
+  function! GetLinterNames(filetype) abort
+    return map(ale#linter#Get(a:filetype), 'v:val.name')
+  endfunction
+
+After:
+  Restore
+
+  call ale#linter#Reset()
+
+Execute(The defaults for the csh filetype should be correct):
+  AssertEqual ['shell'], GetLinterNames('csh')
+
+  let g:ale_linters_explicit = 1
+
+  AssertEqual [], GetLinterNames('csh')
+
+Execute(The defaults for the go filetype should be correct):
+  AssertEqual ['gofmt', 'golint', 'go vet'], GetLinterNames('go')
+
+  let g:ale_linters_explicit = 1
+
+  AssertEqual [], GetLinterNames('go')
+
+Execute(The defaults for the help filetype should be correct):
+  AssertEqual [], GetLinterNames('help')
+
+Execute(The defaults for the python filetype should be correct):
+  AssertEqual ['flake8', 'mypy', 'pylint'], GetLinterNames('python')
+
+  let g:ale_linters_explicit = 1
+
+  AssertEqual [], GetLinterNames('python')
+
+Execute(The defaults for the rust filetype should be correct):
+  AssertEqual ['cargo'], GetLinterNames('rust')
+
+  let g:ale_linters_explicit = 1
+
+  AssertEqual [], GetLinterNames('rust')
+
+Execute(The defaults for the spec filetype should be correct):
+  AssertEqual [], GetLinterNames('spec')
+
+Execute(The defaults for the text filetype should be correct):
+  AssertEqual [], GetLinterNames('text')
+
+Execute(The defaults for the zsh filetype should be correct):
+  AssertEqual ['shell'], GetLinterNames('zsh')
+
+  let g:ale_linters_explicit = 1
+
+  AssertEqual [], GetLinterNames('zsh')
+
+Execute(The defaults for the verilog filetype should be correct):
+  " This filetype isn't configured with default, so we can test loading all
+  " available linters with this.
+  AssertEqual ['iverilog', 'verilator'], GetLinterNames('verilog')
+
+  let g:ale_linters_explicit = 1
+
+  AssertEqual [], GetLinterNames('verilog')
diff --git a/test/test_linter_retrieval.vader b/test/test_linter_retrieval.vader
index 5d5b582d..5d1ee451 100644
--- a/test/test_linter_retrieval.vader
+++ b/test/test_linter_retrieval.vader
@@ -1,5 +1,6 @@
 Before:
-  Save g:ale_linters, g:ale_linter_aliases
+  Save g:ale_linters
+  Save g:ale_linter_aliases
 
   let g:testlinter1 = {'name': 'testlinter1', 'executable': 'testlinter1', 'command': 'testlinter1', 'callback': 'testCB1', 'output_stream': 'stdout', 'read_buffer': 1, 'lint_file': 0, 'aliases': [], 'lsp': '', 'add_newline': 0}
   let g:testlinter2 = {'name': 'testlinter2', 'executable': 'testlinter2', 'command': 'testlinter2', 'callback': 'testCB2', 'output_stream': 'stdout', 'read_buffer': 0, 'lint_file': 1, 'aliases': [], 'lsp': '', 'add_newline': 0}