Implement .nimble-link files in the compiler and add tests for them.

compiler/nimblecmd.nim

@@ -77,9 +77,20 @@ iterator chosen(packages: StringTableRef): string =
     yield res
 
 proc addNimblePath(p: string, info: TLineInfo) =
-  if not contains(options.searchPaths, p):
+  var path = p
-    message(info, hintPath, p)
+  let nimbleLinks = toSeq(walkPattern(p / "*.nimble-link"))
-    options.lazyPaths.insert(p, 0)
+  if nimbleLinks.len > 0:
+    # If the user has more than one .nimble-link file then... we just ignore it.
+    # Spec for these files is available in Nimble's readme:
+    # https://github.com/nim-lang/nimble#nimble-link
+    let nimbleLinkLines = readFile(nimbleLinks[0]).splitLines()
+    path = nimbleLinkLines[1]
+    if not path.isAbsolute():
+      path = p / path
+
+  if not contains(options.searchPaths, path):
+    message(info, hintPath, path)
+    options.lazyPaths.insert(path, 0)
 
 proc addPathRec(dir: string, info: TLineInfo) =
   var packages = newStringTable(modeStyleInsensitive)

tests/nimble/nimbleDir/linkedPkgs/pkgA-0.1.0/pkgA.nimble-link

@@ -0,0 +1,2 @@
+../../simplePkgs/pkgA-0.1.0/pkgA.nimble
+../../simplePkgs/pkgA-0.1.0/

tests/nimble/nimbleDir/linkedPkgs/pkgB-#head/pkgB.nimble-link

@@ -0,0 +1,2 @@
+../../simplePkgs/pkgB-#head/pkgB.nimble
+../../simplePkgs/pkgB-#head/

tests/nimble/nimbleDir/linkedPkgs/pkgB-0.1.0/pkgB.nimble-link

@@ -0,0 +1,2 @@
+../../simplePkgs/pkgB-0.1.0/pkgB.nimble
+../../simplePkgs/pkgB-0.1.0/

tests/nimble/tnimblepathlink.nim

@@ -0,0 +1,9 @@
+discard """
+  action: run
+  cmd: "nim $target --nimblePath:$fileDir/nimbleDir/linkedPkgs $options $file"
+"""
+import pkgA/module as A
+import pkgB/module as B
+
+doAssert pkgATest() == 1, "Simple linked pkgA-0.1.0 wasn't added to path correctly."
+doAssert pkgBTest() == 0xDEADBEEF, "linked pkgB-#head wasn't picked over pkgB-0.1.0"

tests/testament/tester.nim

@@ -80,7 +80,6 @@ proc callCompiler(cmdTemplate, filename, options: string,
   let c = parseCmdLine(cmdTemplate % ["target", targetToCmd[target],
                        "options", options, "file", filename.quoteShell,
                        "filedir", filename.getFileDir()])
-  echo(c)
   var p = startProcess(command=c[0], args=c[1.. ^1],
                        options={poStdErrToStdOut, poUsePath})
   let outp = p.outputStream