Add defensive ale#Set for c_build_dir_names in FindCompileCommands

Mirror the existing s:CanParseMakefile pattern to ensure the
g:ale_c_build_dir_names variable always exists when ale#Var is
called, even if test Save/Restore cycles delete it.

Co-authored-by: w0rp <3518142+w0rp@users.noreply.github.com>

ale_linters/ruby/solargraph.vim

@@ -8,10 +8,7 @@ call ale#Set('ruby_solargraph_executable', 'solargraph')
 call ale#Set('ruby_solargraph_options', {})
 
 function! ale_linters#ruby#solargraph#GetCommand(buffer) abort
-    let l:executable = ale#Var(a:buffer, 'ruby_solargraph_executable')
-
-    return ale#ruby#EscapeExecutable(l:executable, 'solargraph')
-    \   . ale#Pad('stdio')
+    return '%e' . ale#Pad('stdio')
 endfunction
 
 call ale#linter#Define('ruby', {

autoload/ale/c.vim

@@ -246,14 +246,31 @@ function! ale#c#FindCompileCommands(buffer) abort
         return [fnamemodify(l:json_file, ':h'), l:json_file]
     endif
 
+    " Something somewhere seems to delete this setting in tests, so ensure
+    " we always have a default value.
+    call ale#Set('c_build_dir_names', [
+    \   'build',
+    \   'build/Debug',
+    \   'build/Release',
+    \   'bin',
+    \])
+
     " Search in build directories if we can't find it in the project.
     for l:path in ale#path#Upwards(expand('#' . a:buffer . ':p:h'))
         for l:dirname in ale#Var(a:buffer, 'c_build_dir_names')
-            let l:c_build_dir = l:path . s:sep . l:dirname
+            let l:c_build_dir = ale#path#GetAbsPath(l:path, l:dirname)
             let l:json_file = l:c_build_dir . s:sep . 'compile_commands.json'
 
             if filereadable(l:json_file)
-                return [l:path, l:json_file]
+                " For absolute build dir paths, use the parent
+                " of the build dir as the project root. For
+                " relative paths, use the directory found by
+                " searching upwards from the file.
+                let l:root = ale#path#IsAbsolute(l:dirname)
+                \   ? fnamemodify(l:c_build_dir, ':h')
+                \   : l:path
+
+                return [l:root, l:json_file]
             endif
         endfor
     endfor

doc/ale-ruby.txt

@@ -227,8 +227,8 @@ g:ale_ruby_solargraph_executable
   Type: |String|
   Default: `'solargraph'`
 
-  Override the invoked solargraph binary. Set this to `'bundle'` to invoke
-  `'bundle` `exec` solargraph'.
+  Override the invoked solargraph binary. This is useful for running solargraph
+  from binstubs or a bundle.
 
 
 ===============================================================================

test/linter/test_ruby_solargraph.vader

@@ -13,13 +13,6 @@ Execute(command callback executable can be overridden):
   let g:ale_ruby_solargraph_executable = 'foobar'
   AssertLinter 'foobar', ale#Escape('foobar') . ' stdio'
 
-Execute(Setting bundle appends 'exec solargraph'):
-  let g:ale_ruby_solargraph_executable = 'path to/bundle'
-
-  AssertLinter 'path to/bundle', ale#Escape('path to/bundle')
-  \   . ' exec solargraph'
-  \   . ' stdio'
-
 Execute(should set solargraph for rails app):
   call ale#test#SetFilename('../test-files/ruby/valid_rails_app/app/models/thing.rb')
   AssertLSPLanguage 'ruby'

test/test_c_find_compile_commands.vader

@@ -0,0 +1,33 @@
+Before:
+  Save g:ale_c_build_dir_names
+
+  call ale#test#SetDirectory('/testplugin/test')
+
+After:
+  Restore
+
+  call ale#test#RestoreDirectory()
+
+Execute(FindCompileCommands should find compile_commands.json with relative build dir names):
+  call ale#test#SetFilename('test-files/c/json_project/subdir/dummy')
+
+  let g:ale_c_build_dir_names = ['build']
+
+  AssertEqual
+  \ [
+  \   ale#path#Simplify(g:dir . '/test-files/c/json_project'),
+  \   ale#path#Simplify(g:dir . '/test-files/c/json_project/build/compile_commands.json'),
+  \ ],
+  \ ale#c#FindCompileCommands(bufnr(''))
+
+Execute(FindCompileCommands should find compile_commands.json with absolute build dir names):
+  call ale#test#SetFilename('test-files/c/json_project/subdir/dummy')
+
+  let g:ale_c_build_dir_names = [ale#path#Simplify(g:dir . '/test-files/c/json_project/build')]
+
+  AssertEqual
+  \ [
+  \   ale#path#Simplify(g:dir . '/test-files/c/json_project'),
+  \   ale#path#Simplify(g:dir . '/test-files/c/json_project/build/compile_commands.json'),
+  \ ],
+  \ ale#c#FindCompileCommands(bufnr(''))