#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.

4 files changed, 119 insertions, 143 deletions

diff --git a/doc/ale-c.txt b/doc/ale-c.txt
index fc0d941a..fe28cf4a 100644
--- a/doc/ale-c.txt
+++ b/doc/ale-c.txt
@@ -1,6 +1,9 @@
 ===============================================================================
 ALE C Integration                                               *ale-c-options*
 
+For basic checking of problems with C files, ALE offers the `cc` linter, which
+runs either `clang`, or `gcc`. See |ale-c-cc|.
+
 
 ===============================================================================
 Global Options
@@ -11,12 +14,12 @@ g:ale_c_build_dir_names                               *g:ale_c_build_dir_names*
   Type: |List|
   Default: `['build', 'bin']`
 
-  A list of directory names to be used when searching upwards from cpp
-  files to discover compilation databases with. For directory named `'foo'`,
-  ALE will search for `'foo/compile_commands.json'` in all directories on and above
-  the directory containing the cpp file to find path to compilation database.
-  This feature is useful for the clang tools wrapped around LibTooling (namely
-  here, clang-tidy)
+  A list of directory names to be used when searching upwards from cpp files
+  to discover compilation databases with. For directory named `'foo'`, ALE
+  will search for `'foo/compile_commands.json'` in all directories on and
+  above the directory containing the cpp file to find path to compilation
+  database.  This feature is useful for the clang tools wrapped around
+  LibTooling (namely here, clang-tidy)
 
 
 g:ale_c_build_dir                                           *g:ale_c_build_dir*
@@ -94,22 +97,58 @@ g:ale_c_astyle_project_options                 *g:ale_c_astyle_project_options*
 
 
 ===============================================================================
-clang                                                             *ale-c-clang*
+cc                                                                   *ale-c-cc*
+                                                                    *ale-c-gcc*
+                                                                  *ale-c-clang*
 
-g:ale_c_clang_executable                             *g:ale_c_clang_executable*
-                                                     *b:ale_c_clang_executable*
+g:ale_c_cc_executable                                   *g:ale_c_cc_executable*
+                                                        *b:ale_c_cc_executable*
   Type: |String|
-  Default: `'clang'`
+  Default: `'<auto>'`
+
+  This variable can be changed to use a different executable for a C compiler.
 
-  This variable can be changed to use a different executable for clang.
+  ALE will try to use `clang` if Clang is available, otherwise ALE will
+  default to checking C code with `gcc`.
 
 
-g:ale_c_clang_options                                   *g:ale_c_clang_options*
-                                                        *b:ale_c_clang_options*
+g:ale_c_cc_options                                         *g:ale_c_cc_options*
+                                                           *b:ale_c_cc_options*
   Type: |String|
   Default: `'-std=c11 -Wall'`
 
-  This variable can be changed to modify flags given to clang.
+  This variable can be change to modify flags given to the C compiler.
+
+
+===============================================================================
+ccls                                                               *ale-c-ccls*
+
+g:ale_c_ccls_executable                               *g:ale_c_ccls_executable*
+                                                      *b:ale_c_ccls_executable*
+  Type: |String|
+  Default: `'ccls'`
+
+  This variable can be changed to use a different executable for ccls.
+
+
+g:ale_c_ccls_init_options                           *g:ale_c_ccls_init_options*
+                                                    *b:ale_c_ccls_init_options*
+  Type: |Dictionary|
+  Default: `{}`
+
+  This variable can be changed to customize ccls initialization options.
+  Example: >
+      {
+    \   'cacheDirectory': '/tmp/ccls',
+    \   'cacheFormat': 'binary',
+    \   'diagnostics': {
+    \     'onOpen': 0,
+    \     'opChange': 1000,
+    \   },
+    \ }
+<
+  Visit https://github.com/MaskRay/ccls/wiki/Initialization-options for all
+  available options and explanations.
 
 
 ===============================================================================
@@ -295,25 +334,6 @@ g:ale_c_flawfinder_error_severity           *g:ale_c_flawfinder_error_severity*
 
 
 ===============================================================================
-gcc                                                                 *ale-c-gcc*
-
-g:ale_c_gcc_executable                                 *g:ale_c_gcc_executable*
-                                                       *b:ale_c_gcc_executable*
-  Type: |String|
-  Default: `'gcc'`
-
-  This variable can be changed to use a different executable for gcc.
-
-
-g:ale_c_gcc_options                                       *g:ale_c_gcc_options*
-                                                          *b:ale_c_gcc_options*
-  Type: |String|
-  Default: `'-std=c11 -Wall'`
-
-  This variable can be change to modify flags given to gcc.
-
-
-===============================================================================
 uncrustify                                                   *ale-c-uncrustify*
 
 g:ale_c_uncrustify_executable                   *g:ale_c_uncrustify_executable*
@@ -333,35 +353,4 @@ g:ale_c_uncrustify_options                         *g:ale_c_uncrustify_options*
 
 
 ===============================================================================
-ccls                                                               *ale-c-ccls*
-
-g:ale_c_ccls_executable                               *g:ale_c_ccls_executable*
-                                                      *b:ale_c_ccls_executable*
-  Type: |String|
-  Default: `'ccls'`
-
-  This variable can be changed to use a different executable for ccls.
-
-
-g:ale_c_ccls_init_options                           *g:ale_c_ccls_init_options*
-                                                    *b:ale_c_ccls_init_options*
-  Type: |Dictionary|
-  Default: `{}`
-
-  This variable can be changed to customize ccls initialization options.
-  Example: >
-      {
-    \   'cacheDirectory': '/tmp/ccls',
-    \   'cacheFormat': 'binary',
-    \   'diagnostics': {
-    \     'onOpen': 0,
-    \     'opChange': 1000,
-    \   },
-    \ }
-<
-  Visit https://github.com/MaskRay/ccls/wiki/Initialization-options for all
-  available options and explanations.
-
-
-===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:
diff --git a/doc/ale-cpp.txt b/doc/ale-cpp.txt
index fbe31370..651b4160 100644
--- a/doc/ale-cpp.txt
+++ b/doc/ale-cpp.txt
@@ -1,6 +1,9 @@
 ===============================================================================
 ALE C++ Integration                                           *ale-cpp-options*
 
+For basic checking of problems with C++ files, ALE offers the `cc` linter,
+which runs either `clang++`, or `gcc`. See |ale-cpp-cc|.
+
 
 ===============================================================================
 Global Options
@@ -38,41 +41,58 @@ g:ale_cpp_astyle_project_options             *g:ale_cpp_astyle_project_options*
 
 
 ===============================================================================
-clang                                                           *ale-cpp-clang*
+cc                                                                 *ale-cpp-cc*
+                                                                  *ale-cpp-gcc*
+                                                                *ale-cpp-clang*
 
-g:ale_cpp_clang_executable                         *g:ale_cpp_clang_executable*
-                                                   *b:ale_cpp_clang_executable*
+g:ale_cpp_cc_executable                               *g:ale_cpp_cc_executable*
+                                                      *b:ale_cpp_cc_executable*
   Type: |String|
-  Default: `'clang++'`
+  Default: `'<auto>'`
+
+  This variable can be changed to use a different executable for a C++ compiler.
 
-  This variable can be changed to use a different executable for clang.
+  ALE will try to use `clang++` if Clang is available, otherwise ALE will
+  default to checking C++ code with `gcc`.
 
 
-g:ale_cpp_clang_options                               *g:ale_cpp_clang_options*
-                                                      *b:ale_cpp_clang_options*
+g:ale_cpp_cc_options                                     *g:ale_cpp_cc_options*
+                                                         *b:ale_cpp_cc_options*
   Type: |String|
   Default: `'-std=c++14 -Wall'`
 
-  This variable can be changed to modify flags given to clang.
+  This variable can be change to modify flags given to the C++ compiler.
 
 
 ===============================================================================
-clangd                                                         *ale-cpp-clangd*
+ccls                                                             *ale-cpp-ccls*
 
-g:ale_cpp_clangd_executable                       *g:ale_cpp_clangd_executable*
-                                                  *b:ale_cpp_clangd_executable*
+g:ale_cpp_ccls_executable                           *g:ale_cpp_ccls_executable*
+                                                    *b:ale_cpp_ccls_executable*
   Type: |String|
-  Default: `'clangd'`
+  Default: `'ccls'`
 
-  This variable can be changed to use a different executable for clangd.
+  This variable can be changed to use a different executable for ccls.
 
 
-g:ale_cpp_clangd_options                             *g:ale_cpp_clangd_options*
-                                                     *b:ale_cpp_clangd_options*
-  Type: |String|
-  Default: `''`
+g:ale_cpp_ccls_init_options                       *g:ale_cpp_ccls_init_options*
+                                                  *b:ale_cpp_ccls_init_options*
+  Type: |Dictionary|
+  Default: `{}`
 
-  This variable can be changed to modify flags given to clangd.
+  This variable can be changed to customize ccls initialization options.
+  Example: >
+      {
+    \   'cacheDirectory': '/tmp/ccls',
+    \   'cacheFormat': 'binary',
+    \   'diagnostics': {
+    \     'onOpen': 0,
+    \     'opChange': 1000,
+    \   },
+    \ }
+<
+  Visit https://github.com/MaskRay/ccls/wiki/Initialization-options for all
+  available options and explanations.
 
 
 ===============================================================================
@@ -107,6 +127,25 @@ g:ale_cpp_clangcheck_options                     *g:ale_cpp_clangcheck_options*
 
 
 ===============================================================================
+clangd                                                         *ale-cpp-clangd*
+
+g:ale_cpp_clangd_executable                       *g:ale_cpp_clangd_executable*
+                                                  *b:ale_cpp_clangd_executable*
+  Type: |String|
+  Default: `'clangd'`
+
+  This variable can be changed to use a different executable for clangd.
+
+
+g:ale_cpp_clangd_options                             *g:ale_cpp_clangd_options*
+                                                     *b:ale_cpp_clangd_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be changed to modify flags given to clangd.
+
+
+===============================================================================
 clang-format                                              *ale-cpp-clangformat*
 
 See |ale-c-clangformat| for information about the available options.
@@ -296,60 +335,10 @@ g:ale_cpp_flawfinder_options                             *g:ale-cpp-flawfinder*
 
 
 ===============================================================================
-gcc                                                               *ale-cpp-gcc*
-
-g:ale_cpp_gcc_executable                             *g:ale_cpp_gcc_executable*
-                                                     *b:ale_cpp_gcc_executable*
-  Type: |String|
-  Default: `'gcc'`
-
-  This variable can be changed to use a different executable for gcc.
-
-
-g:ale_cpp_gcc_options                                   *g:ale_cpp_gcc_options*
-                                                        *b:ale_cpp_gcc_options*
-  Type: |String|
-  Default: `'-std=c++14 -Wall'`
-
-  This variable can be changed to modify flags given to gcc.
-
-
-===============================================================================
 uncrustify                                                 *ale-cpp-uncrustify*
 
 See |ale-c-uncrustify| for information about the available options.
 
 
 ===============================================================================
-ccls                                                             *ale-cpp-ccls*
-
-g:ale_cpp_ccls_executable                           *g:ale_cpp_ccls_executable*
-                                                    *b:ale_cpp_ccls_executable*
-  Type: |String|
-  Default: `'ccls'`
-
-  This variable can be changed to use a different executable for ccls.
-
-
-g:ale_cpp_ccls_init_options                       *g:ale_cpp_ccls_init_options*
-                                                  *b:ale_cpp_ccls_init_options*
-  Type: |Dictionary|
-  Default: `{}`
-
-  This variable can be changed to customize ccls initialization options.
-  Example: >
-      {
-    \   'cacheDirectory': '/tmp/ccls',
-    \   'cacheFormat': 'binary',
-    \   'diagnostics': {
-    \     'onOpen': 0,
-    \     'opChange': 1000,
-    \   },
-    \ }
-<
-  Visit https://github.com/MaskRay/ccls/wiki/Initialization-options for all
-  available options and explanations.
-
-
-===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:
diff --git a/doc/ale-supported-languages-and-tools.txt b/doc/ale-supported-languages-and-tools.txt
index 632dc468..677267d8 100644
--- a/doc/ale-supported-languages-and-tools.txt
+++ b/doc/ale-supported-languages-and-tools.txt
@@ -48,7 +48,7 @@ Notes:
 * C
   * `astyle`
   * `ccls`
-  * `clang`
+  * `clang` (`cc`)
   * `clangd`
   * `clang-format`
   * `clangtidy`!!
@@ -56,7 +56,7 @@ Notes:
   * `cpplint`!!
   * `cquery`
   * `flawfinder`
-  * `gcc`
+  * `gcc` (`cc`)
   * `uncrustify`
 * C#
   * `csc`!!
@@ -66,7 +66,7 @@ Notes:
 * C++ (filetype cpp)
   * `astyle`
   * `ccls`
-  * `clang`
+  * `clang` (`cc`)
   * `clangcheck`!!
   * `clangd`
   * `clang-format`
@@ -76,7 +76,7 @@ Notes:
   * `cpplint`!!
   * `cquery`
   * `flawfinder`
-  * `gcc`
+  * `gcc` (`cc`)
   * `uncrustify`
 * Chef
   * `cookstyle`
diff --git a/doc/ale.txt b/doc/ale.txt
index 606fe72c..81271105 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -2322,16 +2322,15 @@ documented in additional help files.
     bibclean..............................|ale-bib-bibclean|
   c.......................................|ale-c-options|
     astyle................................|ale-c-astyle|
-    clang.................................|ale-c-clang|
+    cc....................................|ale-c-cc|
+    ccls..................................|ale-c-ccls|
     clangd................................|ale-c-clangd|
     clang-format..........................|ale-c-clangformat|
     clangtidy.............................|ale-c-clangtidy|
     cppcheck..............................|ale-c-cppcheck|
     cquery................................|ale-c-cquery|
     flawfinder............................|ale-c-flawfinder|
-    gcc...................................|ale-c-gcc|
     uncrustify............................|ale-c-uncrustify|
-    ccls..................................|ale-c-ccls|
   chef....................................|ale-chef-options|
     cookstyle.............................|ale-chef-cookstyle|
     foodcritic............................|ale-chef-foodcritic|
@@ -2345,9 +2344,10 @@ documented in additional help files.
     cmake-format..........................|ale-cmake-cmakeformat|
   cpp.....................................|ale-cpp-options|
     astyle................................|ale-cpp-astyle|
-    clang.................................|ale-cpp-clang|
-    clangd................................|ale-cpp-clangd|
+    cc....................................|ale-cpp-cc|
+    ccls..................................|ale-cpp-ccls|
     clangcheck............................|ale-cpp-clangcheck|
+    clangd................................|ale-cpp-clangd|
     clang-format..........................|ale-cpp-clangformat|
     clangtidy.............................|ale-cpp-clangtidy|
     clazy.................................|ale-cpp-clazy|
@@ -2355,9 +2355,7 @@ documented in additional help files.
     cpplint...............................|ale-cpp-cpplint|
     cquery................................|ale-cpp-cquery|
     flawfinder............................|ale-cpp-flawfinder|
-    gcc...................................|ale-cpp-gcc|
     uncrustify............................|ale-cpp-uncrustify|
-    ccls..................................|ale-cpp-ccls|
   c#......................................|ale-cs-options|
     csc...................................|ale-cs-csc|
     mcs...................................|ale-cs-mcs|