Merge autoadd of c++ libraries during linking.

compiler/main.stanza

@@ -128,17 +128,20 @@ defn build-system (verbose?:True|False) :
       defn emit-args (ss:Seqable<String>) : do(emit-arg, ss)
 
       ;Compiler name
-      emit-arg $ switch(platform) :
+      val cc-prog = switch(platform) :
         `os-x : "cc"
         `linux : "cc"
-        `windows : "gcc"
+        `windows : "gcc"      
+      emit-arg(cc-prog)
 
       ;All files
       emit-arg(asm)
       emit-args(ccfiles)
 
-      ;All flags
+      ;User flags
       emit-args(ccflags)
+
+      ;Output file.
       emit-args(["-o" output])
 
       ;Output for debugging
@@ -148,11 +151,18 @@ defn build-system (verbose?:True|False) :
           for a in args do :
             println("%~" % [a])
 
-      ;Call system
-      val return-code = call-system(args[0], to-tuple(args))
-
-      ;Return true if successful
-      return-code == 0
+      ;First directly try calling the cc-prog driver.
+      try :
+        ;Call system
+        val return-code = call-system(to-tuple(args))        
+        ;Return true if successful
+        return-code == 0
+
+      ;If this particular type of error occurs, then
+      ;double-check whether GCC is installed.
+      catch (e:ProcessLaunchError) :
+        ensure-cc-installed(cc-prog)
+        throw(e)
 
     defmethod call-shell (this, platform:Symbol, command:String) :
       if verbose? :
@@ -183,6 +193,21 @@ defn build-system (verbose?:True|False) :
         println("Delete temporary file %~." % [file])
       delete-file(file)
 
+;Helper: Check whether the given cc driver is installed.
+;If it isn't, then an error is thrown asking the user to install it.
+;If it is installed, or if some error occurs when attempting to check
+;then false is returned.
+defn ensure-cc-installed (cc:String) -> False :
+  try :
+    call-system([cc "--version"])
+    false
+  catch (e:ProcessLaunchError) :
+    val msg = "Stanza requires a C compiler to be installed and executable via \
+               the %~ command. Please double-check this and run again."
+    throw(Exception(msg % [cc]))
+  catch (e2) :
+    false
+
 ;============================================================
 ;================= Common Stanza Flags ======================
 ;============================================================

compiler/system-dependencies.stanza

@@ -11,7 +11,7 @@ public defn system-dependencies (platform:Symbol) -> ProjDependencies :
   val ccflags = Vector<String>()
 
   ;C Standard
-  add(ccflags, "-std=gnu99")
+  add(ccflags, "-std=gnu11")
 
   ;Use static linking on windows
   if platform == `windows :
@@ -40,6 +40,12 @@ public defn system-dependencies (platform:Symbol) -> ProjDependencies :
   if platform == `linux :
     add(ccflags, "-D_GNU_SOURCE")
 
+  ;Include standard C++ library.
+  switch(platform) :
+    `os-x : add(ccflags, "-lc++")
+    `linux : add(ccflags, "-lstdc++")
+    `windows : add(ccflags, "-lstdc++")
+
   ;Stanza include dir
   add(ccflags, to-string("-I%_" % [system-filepath(StanzaIncludeDir)]))