nim doc can run code blocks (#9228)

compiler/docgen.nim

@@ -141,9 +141,30 @@ proc newDocumentor*(filename: AbsoluteFile; cache: IdentCache; conf: ConfigRef,
   result.id = 100
   result.jArray = newJArray()
   initStrTable result.types
-  result.onTestSnippet = proc (d: var RstGenerator; filename, cmd: string; status: int; content: string) =
+  result.onTestSnippet =
-    localError(conf, newLineInfo(conf, AbsoluteFile d.filename, -1, -1),
+    proc (gen: var RstGenerator; filename, cmd: string; status: int; content: string) =
-               warnUser, "only 'rst2html' supports the ':test:' attribute")
+    var d = TDocumentor(gen)
+    var outp: AbsoluteFile
+    if filename.len == 0:
+      inc(d.id)
+      let nameOnly = splitFile(d.filename).name
+      let subdir = getNimcacheDir(conf) / RelativeDir(nameOnly)
+      createDir(subdir)
+      outp = subdir / RelativeFile(nameOnly & "_snippet_" & $d.id & ".nim")
+    elif isAbsolute(filename):
+      outp = AbsoluteFile filename
+    else:
+      # Nim's convention: every path is relative to the file it was written in:
+      outp = splitFile(d.filename).dir.AbsoluteDir / RelativeFile(filename)
+    # Include the current file if we're parsing a nim file
+    let importStmt = if d.isPureRst: "" else: "import \"$1\"\n" % [d.filename]
+    writeFile(outp, importStmt & content)
+    let c = if cmd.startsWith("nim "): os.getAppFilename() & cmd.substr(3)
+            else: cmd
+    let c2 = c % quoteShell(outp)
+    rawMessage(conf, hintExecuting, c2)
+    if execShellCmd(c2) != status:
+      rawMessage(conf, errGenerated, "executing of external program failed: " & c2)
   result.emitted = initIntSet()
   result.destFile = getOutFile2(conf, relativeTo(filename, conf.projectPath),
                                 outExt, RelativeDir"htmldocs", false)
@@ -961,27 +982,6 @@ proc commandRstAux(cache: IdentCache, conf: ConfigRef;
                    filename: AbsoluteFile, outExt: string) =
   var filen = addFileExt(filename, "txt")
   var d = newDocumentor(filen, cache, conf, outExt)
-  d.onTestSnippet = proc (d: var RstGenerator; filename, cmd: string;
-                          status: int; content: string) =
-    var outp: AbsoluteFile
-    if filename.len == 0:
-      inc(d.id)
-      let nameOnly = splitFile(d.filename).name
-      let subdir = getNimcacheDir(conf) / RelativeDir(nameOnly)
-      createDir(subdir)
-      outp = subdir / RelativeFile(nameOnly & "_snippet_" & $d.id & ".nim")
-    elif isAbsolute(filename):
-      outp = AbsoluteFile filename
-    else:
-      # Nim's convention: every path is relative to the file it was written in:
-      outp = splitFile(d.filename).dir.AbsoluteDir / RelativeFile(filename)
-    writeFile(outp, content)
-    let c = if cmd.startsWith("nim "): os.getAppFilename() & cmd.substr(3)
-            else: cmd
-    let c2 = c % quoteShell(outp)
-    rawMessage(conf, hintExecuting, c2)
-    if execShellCmd(c2) != status:
-      rawMessage(conf, errGenerated, "executing of external program failed: " & c2)
 
   d.isPureRst = true
   var rst = parseRst(readFile(filen.string), filen.string, 0, 1, d.hasToc,
@@ -1002,6 +1002,10 @@ proc commandJson*(cache: IdentCache, conf: ConfigRef) =
   var ast = parseFile(conf.projectMainIdx, cache, conf)
   if ast == nil: return
   var d = newDocumentor(conf.projectFull, cache, conf)
+  d.onTestSnippet = proc (d: var RstGenerator; filename, cmd: string;
+                          status: int; content: string) =
+    localError(conf, newLineInfo(conf, AbsoluteFile d.filename, -1, -1),
+               warnUser, "the ':test:' attribute is not supported by this backend")
   d.hasToc = true
   generateJson(d, ast)
   let json = d.jArray
@@ -1019,6 +1023,10 @@ proc commandTags*(cache: IdentCache, conf: ConfigRef) =
   var ast = parseFile(conf.projectMainIdx, cache, conf)
   if ast == nil: return
   var d = newDocumentor(conf.projectFull, cache, conf)
+  d.onTestSnippet = proc (d: var RstGenerator; filename, cmd: string;
+                          status: int; content: string) =
+    localError(conf, newLineInfo(conf, AbsoluteFile d.filename, -1, -1),
+               warnUser, "the ':test:' attribute is not supported by this backend")
   d.hasToc = true
   var
     content: Rope