Fix #583 - False negative for missing parameter in Params

src/dscanner/analysis/properly_documented_public_functions.d

@@ -166,8 +166,11 @@ private:
 		import std.array : array;
 
 		const comment = parseComment(commentText, null);
-		if (!comment.isDitto && !withinTemplate)
-		{
+		if (withinTemplate) {
+			const paramSection = comment.sections.find!(s => s.name == "Params");
+			if (!paramSection.empty)
+				lastSeenFun.ddocParams ~= paramSection[0].mapping.map!(a => a[0]).array;
+		} else if (!comment.isDitto) {
 			// check old function for invalid ddoc params
 			if (lastSeenFun.active)
 				postCheckSeenDdocParams();
@@ -796,6 +799,40 @@ string bar(P, R)(R r){}// [warn]: %s
 	}c.format(
 		ProperlyDocumentedPublicFunctions.MISSING_TEMPLATE_PARAMS_MESSAGE.format("P")
 	), sac);
+}
+
+// https://github.com/dlang-community/D-Scanner/issues/583
+unittest
+{
+	StaticAnalysisConfig sac = disabledConfig;
+	sac.properly_documented_public_functions = Check.enabled;
+
+	assertAnalyzerWarnings(q{
+	/++
+	Implements the homonym function (also known as `accumulate`)
+
+	Returns:
+	    the accumulated `result`
+
+	Params:
+	    fun = one or more functions
+	+/
+	template reduce(fun...)
+	if (fun.length >= 1)
+	{
+		/++
+		No-seed version. The first element of `r` is used as the seed's value.
+
+		Params:
+			r = an iterable value as defined by `isIterable`
+
+		Returns:
+			the final result of the accumulator applied to the iterable
+		+/
+		auto reduce(R)(R r){}
+	}
+	}c.format(
+	), sac);
 
 	stderr.writeln("Unittest for ProperlyDocumentedPublicFunctions passed.");
 }