added a new feature: --cc:env so that you can use any C compiler as long as it works like GCC

compiler/extccomp.nim

@@ -240,15 +240,15 @@ compiler tcc:
     props: {hasSwitchRange, hasComputedGoto, hasGnuAsm})
 
 # Your C Compiler
-compiler ucc:
+compiler envcc:
   result = (
-    name: "ucc",
+    name: "env",
     objExt: "o",
     optSpeed: " -O3 ",
     optSize: " -O1 ",
-    compilerExe: "cc",
+    compilerExe: "",
     cppCompiler: "",
-    compileTmpl: "-c $options $include -o $objfile $file",
+    compileTmpl: "-c $ccenvflags $options $include -o $objfile $file",
     buildGui: "",
     buildDll: " -shared ",
     buildLib: "", # XXX: not supported yet
@@ -263,7 +263,7 @@ compiler ucc:
     structStmtFmt: "$1 $2",
     produceAsm: "",
     cppXsupport: "",
-    props: {})
+    props: {hasGnuAsm})
 
 const
   CC*: array[succ(low(TSystemCC))..high(TSystemCC), TInfoCC] = [
@@ -274,7 +274,7 @@ const
     bcc(),
     vcc(),
     tcc(),
-    ucc(),
+    envcc(),
     icl(),
     icc(),
     clangcl()]
@@ -483,7 +483,19 @@ proc needsExeExt(conf: ConfigRef): bool {.inline.} =
 proc useCpp(conf: ConfigRef; cfile: AbsoluteFile): bool =
   conf.cmd == cmdCompileToCpp and not cfile.string.endsWith(".c")
 
+proc envFlags(conf: ConfigRef): string =
+  result = if conf.cmd == cmdCompileToCpp:
+            getEnv("CXXFLAGS")
+          else:
+            getEnv("CFLAGS")
+
 proc getCompilerExe(conf: ConfigRef; compiler: TSystemCC; cfile: AbsoluteFile): string =
+  if compiler == ccEnv:
+    result = if useCpp(conf, cfile):
+              getEnv("CXX")
+            else:
+              getEnv("CC")
+  else:
     result = if useCpp(conf, cfile):
               CC[compiler].cppCompiler
             else:
@@ -581,7 +593,8 @@ proc getCompileCFileCmd*(conf: ConfigRef; cfile: Cfile,
     "dfile", dfile,
     "file", cfsh, "objfile", quoteShell(objfile), "options", options,
     "include", includeCmd, "nim", getPrefixDir(conf).string,
-    "lib", conf.libpath.string])
+    "lib", conf.libpath.string,
+    "ccenvflags", envFlags(conf)])
 
   if optProduceAsm in conf.globalOptions:
     if CC[conf.cCompiler].produceAsm.len > 0:
@@ -601,7 +614,8 @@ proc getCompileCFileCmd*(conf: ConfigRef; cfile: Cfile,
     "options", options, "include", includeCmd,
     "nim", quoteShell(getPrefixDir(conf)),
     "lib", quoteShell(conf.libpath),
-    "vccplatform", vccplatform(conf)])
+    "vccplatform", vccplatform(conf),
+    "ccenvflags", envFlags(conf)])
 
 proc footprint(conf: ConfigRef; cfile: Cfile): SecureHash =
   result = secureHash(

compiler/options.nim

@@ -165,7 +165,7 @@ type
 
   TSystemCC* = enum
     ccNone, ccGcc, ccNintendoSwitch, ccLLVM_Gcc, ccCLang, ccBcc, ccVcc,
-    ccTcc, ccUcc, ccIcl, ccIcc, ccClangCl
+    ccTcc, ccEnv, ccIcl, ccIcc, ccClangCl
 
   ExceptionSystem* = enum
     excNone,   # no exception system selected yet

doc/nimc.rst

@@ -240,6 +240,10 @@ add the ``-f`` flag to force all files to be recompiled.
 The default compiler is defined at the top of ``config\nim.cfg``.
 Changing this setting affects the compiler used by ``koch`` to (re)build Nim.
 
+To use the ``CC`` environment variable, use ``nim c --cc:env myfile.nim``. To use the
+``CXX`` environment variable, use ``nim cpp --cc:env myfile.nim``. ``--cc:env`` is available
+since Nim version 1.4.
+
 
 Cross compilation
 =================