make it easier to figure out how to debug issues (#14477)

compiler/lineinfos.nim

@@ -13,7 +13,17 @@
 import ropes, tables, pathutils
 
 const
-  explanationsBaseUrl* = "https://nim-lang.org/docs"
+  explanationsBaseUrl* = "https://nim-lang.github.io/Nim"
+    # was: "https://nim-lang.org/docs" but we're now usually showing devel docs
+    # instead of latest release docs.
+
+proc createDocLink*(urlSuffix: string): string =
+  # os.`/` is not appropriate for urls.
+  result = explanationsBaseUrl
+  if urlSuffix.len > 0 and urlSuffix[0] == '/':
+    result.add urlSuffix
+  else:
+    result.add "/" & urlSuffix
 
 type
   TMsgKind* = enum

compiler/msgs.nim

@@ -385,9 +385,10 @@ proc quit(conf: ConfigRef; msg: TMsgKind) {.gcsafe.} =
       if stackTraceAvailable() and isNil(conf.writelnHook):
         writeStackTrace()
       else:
-        styledMsgWriteln(fgRed, "No stack traceback available\n" &
-            "To create a stacktrace, rerun compilation with ./koch temp " &
-            conf.command & " <file>")
+        styledMsgWriteln(fgRed, """
+No stack traceback available
+To create a stacktrace, rerun compilation with './koch temp $1 <file>', see $2 for details""" %
+          [conf.command, "intern.html#debugging-the-compiler".createDocLink])
   quit 1
 
 proc handleError(conf: ConfigRef; msg: TMsgKind, eh: TErrorHandling, s: string) =

compiler/semexprs.nim

@@ -1572,12 +1572,13 @@ proc takeImplicitAddr(c: PContext, n: PNode; isLent: bool): PNode =
   # return a view into the first argument (if there is one):
   let root = exprRoot(n)
   if root != nil and root.owner == c.p.owner:
+    template url: string = "var_t_return.html".createDocLink
     if root.kind in {skLet, skVar, skTemp} and sfGlobal notin root.flags:
-      localError(c.config, n.info, "'$1' escapes its stack frame; context: '$2'; see $3/var_t_return.html" % [
-        root.name.s, renderTree(n, {renderNoComments}), explanationsBaseUrl])
+      localError(c.config, n.info, "'$1' escapes its stack frame; context: '$2'; see $3" % [
+        root.name.s, renderTree(n, {renderNoComments}), url])
     elif root.kind == skParam and root.position != 0:
-      localError(c.config, n.info, "'$1' is not the first parameter; context: '$2'; see $3/var_t_return.html" % [
-        root.name.s, renderTree(n, {renderNoComments}), explanationsBaseUrl])
+      localError(c.config, n.info, "'$1' is not the first parameter; context: '$2'; see $3" % [
+        root.name.s, renderTree(n, {renderNoComments}), url])
   case n.kind
   of nkHiddenAddr, nkAddr: return n
   of nkDerefExpr: return n[0]