zero to hero: nimble is able to function without nim in the path

src/nimble.nim

@@ -2374,7 +2374,7 @@ proc setNimBin*(options: var Options) =
       # Just filename, search in PATH - nim_temp shortcut
       let pnim = findExe(nimBin)
       if pnim.len != 0: 
-        options.nimBin = some makeNimBin(pnim)
+        options.nimBin = some makeNimBin(options, pnim)
 
     if not fileExists(options.nimBin.get.path):
       raise nimbleError("Unable to find `$1`" % options.nimBin.get.path)
@@ -2404,14 +2404,14 @@ proc setNimBin*(options: var Options) =
         break
 
   # Search PATH to find nim to continue with
-  if options.nimBin.isNone or options.useSystemNim:
-    options.nimBin = some makeNimBin(findExe("nim"))
+  let nimBin = findExe("nim")
+  if nimBin != "" or options.useSystemNim: #when using systemNim is on we want to fail if system nim is not found
+    options.nimBin = some makeNimBin(options, nimBin)
     if options.useSystemNim:
       return
 
   proc install(package: PkgTuple, options: Options): HashSet[PackageInfo] =
     result = install(@[package], options, doPrompt = false, first = false, fromLockFile = false).deps
-
   if options.nimBin.isNone:
     # Search installed packages to continue with
     let nimVersion = ("nim", VersionRange(kind: verAny))

src/nimblepkg/nimenv.nim

@@ -114,7 +114,7 @@ proc useNimFromDir*(options: var Options, realDir: string, v: VersionRange, tryC
       raise nimbleError("Trying to use nim from $1 " % realDir,
                         "If you are using develop mode nim make sure to compile it.")
 
-  options.nimBin = some makeNimBin(nim)
+  options.nimBin = some makeNimBin(options, nim)
   let separator = when defined(windows): ";" else: ":"
 
   putEnv("PATH", realDir / "bin" & separator & getEnv("PATH"))

src/nimblepkg/options.nim

@@ -475,7 +475,7 @@ proc getNimBin*(pkgInfo: PackageInfo, options: Options): string =
       binaryPath &= ".exe"      
     result = pkgInfo.getNimbleFileDir() / binaryPath
   else: 
-    if options.useSatSolver:
+    if options.useSatSolver and not options.useSystemNim:
       #Try to first use nim from the solved packages
       #TODO add the solved packages to the options (we need to remove the legacy solver first otherwise it will be messy)
       for pkg in satProccesedPackages:
@@ -562,18 +562,19 @@ proc getNimVersionFromBin*(nimBin: string): Option[Version] =
         let ver = $major & "." & $minor & "." & $patch
         return some newVersion(ver)
 
-proc makeNimBin*(path: string, version: Option[Version] = none(Version)): NimBin =
+proc makeNimBin*(options: Options, path: string, nimVersion: Option[Version] = none(Version)): NimBin =
   var path = path
   if path == "nim":
     path = findExe("nim")
-  if path == "nim":
+  if path == "":
     raise nimbleError("Unable to find `nim` binary - add to $PATH or use `--nim`")
   if not path.isAbsolute():
     path = expandTilde(path).absolutePath()  
-  var version = version
-  if version.isNone:
-    version = getNimVersionFromBin(path)
-  return NimBin(path: path, version: version.get())
+  var nimVersion = nimVersion
+  if nimVersion.isNone:
+    nimVersion = getNimVersionFromBin(path)
+
+  return NimBin(path: path, version: nimVersion.get())
 
 proc parseFlag*(flag, val: string, result: var Options, kind = cmdLongOption) =
 
@@ -593,7 +594,7 @@ proc parseFlag*(flag, val: string, result: var Options, kind = cmdLongOption) =
   of "offline": result.offline = true
   of "nocolor": result.noColor = true
   of "disablevalidation": result.disableValidation = true
-  of "nim": result.nimBin = some makeNimBin(val)
+  of "nim": result.nimBin = some makeNimBin(result, val)
   of "localdeps", "l": result.localdeps = true
   of "nosslcheck": result.disableSslCertCheck = true
   of "nolockfile": result.disableLockFile = true

tests/tissues.nim

@@ -404,3 +404,13 @@ suite "issues":
       check:
         exitCode == QuitSuccess
         output.strip() == "@[\"nim >= 1.6.16\"]"
+
+  test "issue #1251. Should use the system nim when --useSystemNim flag is on":
+    createDir("testDir-1251")
+    cd "testDir-1251":
+      let (output, exitCode) = execNimble("--useSystemNim", "-l", "install", "nimlangserver")      
+      let nimBin = findExe("nim")
+      let message = "compiling nim package using " & nimBin
+      check exitCode == QuitSuccess
+      check output.contains(message)
+    removeDir("testDir-1251")

tests/tsat.nim

@@ -41,7 +41,7 @@ proc downloadAndStorePackageVersionTableFor(pkgName: string, options: Options) =
 
 proc downloadAllPackages() {.used.} = 
   var options = initOptions()
-  options.nimBin = some makeNimBin("nim")
+  options.nimBin = some options.makeNimBin("nim")
   # options.config.packageLists["uing"] = PackageList(name: pkgName, urls: @[pkgUrl])
   options.config.packageLists["official"] = PackageList(name: "Official", urls: @[
     "https://raw.githubusercontent.com/nim-lang/packages/master/packages.json",
@@ -158,7 +158,7 @@ suite "SAT solver":
     let pkgName: string = "nimlangserver"
     let pv: PkgTuple = (pkgName, VersionRange(kind: verAny))
     var options = initOptions()
-    options.nimBin = some makeNimBin("nim")
+    options.nimBin = some options.makeNimBin("nim")
     options.config.packageLists["official"] = PackageList(name: "Official", urls: @[
       "https://raw.githubusercontent.com/nim-lang/packages/master/packages.json",
       "https://nim-lang.org/nimble/packages.json"
@@ -222,7 +222,7 @@ suite "SAT solver":
       "https://nim-lang.org/nimble/packages.json"
     ])
     options.nimbleDir = getCurrentDir() / "conflictingdepres" / "nimbledeps" 
-    options.nimBin = some makeNimBin("nim")
+    options.nimBin = some options.makeNimBin("nim")
     options.pkgCachePath = getCurrentDir() / "conflictingdepres" / "download"
     let pkgs = getInstalledMinimalPackages(options)
     var pkgVersionTable = initTable[string, PackageVersions]()