Fix #2512 - Use -o /dev/null for gcc linting

ale_linters/asm/gcc.vim

@@ -5,7 +5,10 @@ call ale#Set('asm_gcc_executable', 'gcc')
 call ale#Set('asm_gcc_options', '-Wall')
 
 function! ale_linters#asm#gcc#GetCommand(buffer) abort
-    return '%e -x assembler -fsyntax-only '
+    " `-o /dev/null` or `-o null` is needed to catch all errors,
+    " -fsyntax-only doesn't catch everything.
+    return '%e -x assembler'
+    \   . ' -o ' . g:ale#util#nul_file
     \   . '-iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
     \   . ' ' . ale#Var(a:buffer, 'asm_gcc_options') . ' -'
 endfunction

ale_linters/c/gcc.vim

@@ -9,7 +9,11 @@ function! ale_linters#c#gcc#GetCommand(buffer, output) abort
 
     " -iquote with the directory the file is in makes #include work for
     "  headers in the same directory.
-    return '%e -S -x c -fsyntax-only'
+    "
+    " `-o /dev/null` or `-o null` is needed to catch all errors,
+    " -fsyntax-only doesn't catch everything.
+    return '%e -S -x c'
+    \   . ' -o ' . g:ale#util#nul_file
     \   . ' -iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
     \   . ale#Pad(l:cflags)
     \   . ale#Pad(ale#Var(a:buffer, 'c_gcc_options')) . ' -'

ale_linters/cpp/gcc.vim

@@ -9,7 +9,11 @@ function! ale_linters#cpp#gcc#GetCommand(buffer, output) abort
 
     " -iquote with the directory the file is in makes #include work for
     "  headers in the same directory.
-    return '%e -S -x c++ -fsyntax-only'
+    "
+    " `-o /dev/null` or `-o null` is needed to catch all errors,
+    " -fsyntax-only doesn't catch everything.
+    return '%e -S -x c++'
+    \   . ' -o ' . g:ale#util#nul_file
     \   . ' -iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
     \   . ale#Pad(l:cflags)
     \   . ale#Pad(ale#Var(a:buffer, 'cpp_gcc_options')) . ' -'

autoload/ale/c.vim

@@ -194,6 +194,10 @@ function! s:GetLookupFromCompileCommandsFile(compile_commands_file) abort
     let l:raw_data = []
     silent! let l:raw_data = json_decode(join(readfile(a:compile_commands_file), ''))
 
+    if type(l:raw_data) isnot v:t_list
+        let l:raw_data = []
+    endif
+
     let l:file_lookup = {}
     let l:dir_lookup = {}
 

test/command_callback/test_asm_gcc_command_callbacks.vader

@@ -1,8 +1,9 @@
 Before:
   call ale#assert#SetUpLinterTest('asm', 'gcc')
   call ale#test#SetFilename('test.cpp')
-  let b:command_tail = ' -x assembler -fsyntax-only -iquote'
+  let b:command_tail = ' -x assembler'
-  \   . ' ' . ale#Escape(g:dir)
+  \   . ' -o ' . (has('win32') ? 'nul': '/dev/null')
+  \   . '-iquote ' . ale#Escape(g:dir)
   \   . ' -Wall -'
 
 After:

test/command_callback/test_c_gcc_command_callbacks.vader

@@ -4,8 +4,9 @@ Before:
 
   call ale#assert#SetUpLinterTest('c', 'gcc')
 
-  let b:command_tail = ' -S -x c -fsyntax-only -iquote'
+  let b:command_tail = ' -S -x c'
-  \   . ' ' . ale#Escape(getcwd())
+  \   . ' -o ' . (has('win32') ? 'nul': '/dev/null')
+  \   . ' -iquote ' . ale#Escape(getcwd())
   \   . ' -std=c11 -Wall -'
 
 After:

test/command_callback/test_c_import_paths.vader

@@ -17,6 +17,8 @@ Before:
   let g:ale_c_parse_makefile = 0
 
 After:
+  Restore
+
   unlet! g:original_project_filenames
 
   call ale#assert#TearDownLinterTest()
@@ -28,7 +30,7 @@ Execute(The C GCC handler should include 'include' directories for projects with
 
   AssertLinter 'gcc',
   \ ale#Escape('gcc')
-  \   . ' -S -x c -fsyntax-only'
+  \   . ' -S -x c -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/makefile_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/makefile_project/include'))
   \   . ' -'
@@ -40,7 +42,7 @@ Execute(The C GCC handler should include 'include' directories for projects with
 
   AssertLinter 'gcc',
   \ ale#Escape('gcc')
-  \   . ' -S -x c -fsyntax-only '
+  \   . ' -S -x c -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/configure_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/configure_project/include'))
   \   . ' -'
@@ -52,7 +54,7 @@ Execute(The C GCC handler should include root directories for projects with .h f
 
   AssertLinter 'gcc',
   \ ale#Escape('gcc')
-  \   . ' -S -x c -fsyntax-only '
+  \   . ' -S -x c -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/h_file_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/h_file_project'))
   \   . ' -'
@@ -64,7 +66,7 @@ Execute(The C GCC handler should include root directories for projects with .hpp
 
   AssertLinter 'gcc',
   \ ale#Escape('gcc')
-  \   . ' -S -x c -fsyntax-only '
+  \   . ' -S -x c -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/hpp_file_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/hpp_file_project'))
   \   . ' -'
@@ -124,7 +126,7 @@ Execute(The C++ GCC handler should include 'include' directories for projects wi
 
   AssertLinter 'gcc',
   \   ale#Escape('gcc')
-  \   . ' -S -x c++ -fsyntax-only '
+  \   . ' -S -x c++ -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/makefile_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/makefile_project/include'))
   \   . ' -'
@@ -136,7 +138,7 @@ Execute(The C++ GCC handler should include 'include' directories for projects wi
 
   AssertLinter 'gcc',
   \   ale#Escape('gcc')
-  \   . ' -S -x c++ -fsyntax-only '
+  \   . ' -S -x c++ -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/configure_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/configure_project/include'))
   \   . ' -'
@@ -148,7 +150,7 @@ Execute(The C++ GCC handler should include root directories for projects with .h
 
   AssertLinter 'gcc',
   \   ale#Escape('gcc')
-  \   . ' -S -x c++ -fsyntax-only '
+  \   . ' -S -x c++ -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/h_file_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/h_file_project'))
   \   . ' -'
@@ -160,7 +162,7 @@ Execute(The C++ GCC handler should include root directories for projects with .h
 
   AssertLinter 'gcc',
   \   ale#Escape('gcc')
-  \   . ' -S -x c++ -fsyntax-only '
+  \   . ' -S -x c++ -o ' . (has('win32') ? 'nul': '/dev/null')
   \   . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/hpp_file_project/subdir'))
   \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir .  '/../test_c_projects/hpp_file_project'))
   \   . ' -'

test/command_callback/test_cpp_gcc_command_callbacks.vader

@@ -3,8 +3,9 @@ Before:
   let g:ale_c_parse_makefile = 0
 
   call ale#assert#SetUpLinterTest('cpp', 'gcc')
-  let b:command_tail = ' -S -x c++ -fsyntax-only -iquote'
+  let b:command_tail = ' -S -x c++'
-  \   . ' ' . ale#Escape(getcwd())
+  \   . ' -o ' . (has('win32') ? 'nul': '/dev/null')
+  \   . ' -iquote ' . ale#Escape(getcwd())
   \   . ' -std=c++14 -Wall -'
 
 After: