From 429080ee1c8d6aad2e5e02428baa6f7118afed5d Mon Sep 17 00:00:00 2001
From: "Alexander A. Klimov" <alexander.klimov@icinga.com>
Date: Tue, 27 Aug 2019 13:19:05 +0200
Subject: [PATCH] DSL: warn on x=y if x is a global variable

---
 lib/config/expression.cpp | 54 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/lib/config/expression.cpp b/lib/config/expression.cpp
index 814a15304..b02f2b73c 100644
--- a/lib/config/expression.cpp
+++ b/lib/config/expression.cpp
@@ -552,6 +552,58 @@ ExpressionResult GetScopeExpression::DoEvaluate(ScriptFrame& frame, DebugHint *d
 		VERIFY(!"Invalid scope.");
 }
 
+static inline
+void WarnOnImplicitlySetGlobalVar(const std::unique_ptr<Expression>& setLhs, const Value& setLhsParent, CombinedSetOp setOp, const DebugInfo& debug)
+{
+	auto var (dynamic_cast<VariableExpression*>(setLhs.get()));
+
+	if (var && setLhsParent.IsObject()) {
+		auto ns (dynamic_pointer_cast<Namespace>(setLhsParent.Get<Object::Ptr>()));
+
+		if (ns && ns == ScriptGlobal::GetGlobals()) {
+			const char *opStr = nullptr;
+
+			switch (setOp) {
+				case OpSetLiteral:
+					opStr = "=";
+					break;
+				case OpSetAdd:
+					opStr = "+=";
+					break;
+				case OpSetSubtract:
+					opStr = "-=";
+					break;
+				case OpSetMultiply:
+					opStr = "*=";
+					break;
+				case OpSetDivide:
+					opStr = "/=";
+					break;
+				case OpSetModulo:
+					opStr = "%=";
+					break;
+				case OpSetXor:
+					opStr = "^=";
+					break;
+				case OpSetBinaryAnd:
+					opStr = "&=";
+					break;
+				case OpSetBinaryOr:
+					opStr = "|=";
+					break;
+				default:
+					VERIFY(!"Invalid opcode.");
+			}
+
+			auto varName (var->GetVariable());
+
+			Log(LogWarning, "config")
+				<< "Global variable '" << varName << "' has been set implicitly via '" << varName << ' ' << opStr << " ...' " << debug << "."
+				" Please set it explicitly via 'globals." << varName << ' ' << opStr << " ...' instead.";
+		}
+	}
+}
+
 ExpressionResult SetExpression::DoEvaluate(ScriptFrame& frame, DebugHint *dhint) const
 {
 	if (frame.Sandboxed)
@@ -610,6 +662,8 @@ ExpressionResult SetExpression::DoEvaluate(ScriptFrame& frame, DebugHint *dhint)
 			delete psdhint;
 	}
 
+	WarnOnImplicitlySetGlobalVar(m_Operand1, parent, m_Op, m_DebugInfo);
+
 	return Empty;
 }