Add passNim/p flag to pass compiler flags explicitly.

Remove redundant buildFromDir overload.

src/nimble.nim

@@ -213,13 +213,13 @@ proc processDeps(pkginfo: PackageInfo, options: Options): seq[PackageInfo] =
   for i in reverseDeps:
     addRevDep(options.nimbleData, i, pkginfo)
 
-proc buildFromDir(pkgInfo: PackageInfo, paths: seq[string],
+proc buildFromDir(pkgInfo: PackageInfo, paths, args: seq[string]) =
-                  args: var seq[string]) =
   ## Builds a package as specified by ``pkgInfo``.
   if pkgInfo.bin.len == 0:
     raise newException(NimbleError,
         "Nothing to build. Did you specify a module to build using the" &
         " `bin` key in your .nimble file?")
+  var args = args
   let realDir = pkgInfo.getRealDir()
   for path in paths: args.add("--path:\"" & path & "\" ")
   for bin in pkgInfo.bin:
@@ -244,14 +244,6 @@ proc buildFromDir(pkgInfo: PackageInfo, paths: seq[string],
       exc.hint = hint
       raise exc
 
-proc buildFromDir(pkgInfo: PackageInfo, paths: seq[string], forRelease: bool) =
-  var args: seq[string]
-  if forRelease:
-    args = @["-d:release"]
-  else:
-    args = @[]
-  buildFromDir(pkgInfo, paths, args)
-
 proc removePkgDir(dir: string, options: Options) =
   ## Removes files belonging to the package in ``dir``.
   try:
@@ -356,7 +348,7 @@ proc installFromDir(dir: string, requestedVer: VersionRange, options: Options,
   # if the build fails then the old package will still be installed.
   if pkgInfo.bin.len > 0:
     let paths = result.deps.map(dep => dep.getRealDir())
-    buildFromDir(pkgInfo, paths, true)
+    buildFromDir(pkgInfo, paths, options.action.passNimFlags & "-d:release")
 
   let pkgDestDir = pkgInfo.getPkgDest(options)
   if existsDir(pkgDestDir) and existsFile(pkgDestDir / "nimblemeta.json"):

src/nimblepkg/options.nim

@@ -41,6 +41,7 @@ type
     of actionInstall, actionPath, actionUninstall, actionDevelop:
       packages*: seq[PkgTuple] # Optional only for actionInstall
                                # and actionDevelop.
+      passNimFlags*: seq[string]
     of actionSearch:
       search*: seq[string] # Search string.
     of actionInit, actionDump:
@@ -61,6 +62,7 @@ Usage: nimble COMMAND [opts]
 Commands:
   install      [pkgname, ...]     Installs a list of packages.
                [-d, --depsOnly]   Install only dependencies.
+               [-p, --passNim]    Forward specified flag to compiler.
   develop      [pkgname, ...]     Clones a list of packages for development.
                                   Symlinks the cloned packages or any package
                                   in the current working directory.
@@ -175,6 +177,7 @@ proc initAction*(options: var Options, key: string) =
   case options.action.typ
   of actionInstall, actionPath, actionDevelop, actionUninstall:
     options.action.packages = @[]
+    options.action.passNimFlags = @[]
   of actionCompile, actionDoc, actionBuild:
     options.action.compileOptions = @[]
     options.action.file = ""
@@ -303,6 +306,8 @@ proc parseFlag*(flag, val: string, result: var Options, kind = cmdLongOption) =
       case f
       of "depsonly", "d":
         result.depsOnly = true
+      of "passnim", "p":
+        result.action.passNimFlags.add(val)
       else:
         wasFlagHandled = false
     of actionUninstall: