#3299 Merge gcc and clang into a cc linter

Users can easily be confused when they set some options for a C or C++
compiler, and another compiler is run with different options, which
still reports errors. To remedy this, the existing `gcc` and `clang`
linters have been replaced with a `cc` linter that will run either
compiler.

This is a breaking change for ALE v3.0.0.

ale_linters/cpp/cc.vim

@@ -0,0 +1,53 @@
+" Author: w0rp <devw0rp@gmail.com>
+" Description: A C++ compiler linter for C++ files with gcc/clang, etc.
+
+call ale#Set('cpp_cc_executable', '<auto>')
+call ale#Set('cpp_cc_options', '-std=c++14 -Wall')
+
+function! ale_linters#cpp#cc#GetExecutable(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'cpp_cc_executable')
+
+    " Default to either clang++ or gcc.
+    if l:executable is# '<auto>'
+        if ale#engine#IsExecutable(a:buffer, 'clang++')
+            let l:executable = 'clang++'
+        else
+            let l:executable = 'gcc'
+        endif
+    endif
+
+    return l:executable
+endfunction
+
+function! ale_linters#cpp#cc#GetCommand(buffer, output) abort
+    let l:cflags = ale#c#GetCFlags(a:buffer, a:output)
+    let l:ale_flags = ale#Var(a:buffer, 'cpp_cc_options')
+
+    if l:cflags =~# '-std='
+        let l:ale_flags = substitute(
+        \   l:ale_flags,
+        \   '-std=\(c\|gnu\)++[0-9]\{2\}',
+        \   '',
+        \   'g')
+    endif
+
+    " -iquote with the directory the file is in makes #include work for
+    "  headers in the same directory.
+    "
+    " `-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(l:ale_flags) . ' -'
+endfunction
+
+call ale#linter#Define('cpp', {
+\   'name': 'cc',
+\   'aliases': ['gcc', 'clang', 'g++', 'clang++'],
+\   'output_stream': 'stderr',
+\   'executable': function('ale_linters#cpp#cc#GetExecutable'),
+\   'command': {b -> ale#c#RunMakeCommand(b, function('ale_linters#cpp#cc#GetCommand'))},
+\   'callback': 'ale#handlers#gcc#HandleGCCFormatWithIncludes',
+\})

ale_linters/cpp/clang.vim

@@ -1,33 +0,0 @@
-" Author: Tomota Nakamura <https://github.com/tomotanakamura>
-" Description: clang linter for cpp files
-
-call ale#Set('cpp_clang_executable', 'clang++')
-call ale#Set('cpp_clang_options', '-std=c++14 -Wall')
-
-function! ale_linters#cpp#clang#GetCommand(buffer, output) abort
-    let l:cflags = ale#c#GetCFlags(a:buffer, a:output)
-    let l:ale_flags = ale#Var(a:buffer, 'cpp_clang_options')
-
-    if l:cflags =~# '-std='
-        let l:ale_flags = substitute(
-        \   l:ale_flags,
-        \   '-std=\(c\|gnu\)++[0-9]\{2\}',
-        \   '',
-        \   'g')
-    endif
-
-    " -iquote with the directory the file is in makes #include work for
-    "  headers in the same directory.
-    return '%e -S -x c++ -fsyntax-only'
-    \   . ' -iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
-    \   . ale#Pad(l:cflags)
-    \   . ale#Pad(l:ale_flags) . ' -'
-endfunction
-
-call ale#linter#Define('cpp', {
-\   'name': 'clang',
-\   'output_stream': 'stderr',
-\   'executable': {b -> ale#Var(b, 'cpp_clang_executable')},
-\   'command': {b -> ale#c#RunMakeCommand(b, function('ale_linters#cpp#clang#GetCommand'))},
-\   'callback': 'ale#handlers#gcc#HandleGCCFormatWithIncludes',
-\})

ale_linters/cpp/gcc.vim

@@ -1,38 +0,0 @@
-" Author: geam <mdelage@student.42.fr>
-" Description: gcc linter for cpp files
-"
-call ale#Set('cpp_gcc_executable', 'gcc')
-call ale#Set('cpp_gcc_options', '-std=c++14 -Wall')
-
-function! ale_linters#cpp#gcc#GetCommand(buffer, output) abort
-    let l:cflags = ale#c#GetCFlags(a:buffer, a:output)
-    let l:ale_flags = ale#Var(a:buffer, 'cpp_gcc_options')
-
-    if l:cflags =~# '-std='
-        let l:ale_flags = substitute(
-        \   l:ale_flags,
-        \   '-std=\(c\|gnu\)++[0-9]\{2\}',
-        \   '',
-        \   'g')
-    endif
-
-    " -iquote with the directory the file is in makes #include work for
-    "  headers in the same directory.
-    "
-    " `-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(l:ale_flags) . ' -'
-endfunction
-
-call ale#linter#Define('cpp', {
-\   'name': 'gcc',
-\   'aliases': ['g++'],
-\   'output_stream': 'stderr',
-\   'executable': {b -> ale#Var(b, 'cpp_gcc_executable')},
-\   'command': {b -> ale#c#RunMakeCommand(b, function('ale_linters#cpp#gcc#GetCommand'))},
-\   'callback': 'ale#handlers#gcc#HandleGCCFormatWithIncludes',
-\})