From 74c48443571272284efe15994468944310b723c0 Mon Sep 17 00:00:00 2001
From: Jonah Graham <jonah@kichwacoders.com>
Date: Tue, 25 Feb 2025 21:55:40 -0500
Subject: [PATCH] Avoid null value being converted to "null" string in
 environment (#1096)

If the CDT Variable is APPEND or PREPEND, and the incoming environment
did not contain that variable name, the resulting environment would
have null.

For example, if PATH was not set on the incoming environment, and
PATH was supposed to be prepended with /usr/bin, this method
would have set PATH=/usr/bin:null

This change ensures that the delimeter + null are not prended/appended
when the incoming value is null.
---
 .../envvar/EnvironmentVariableManager.java    | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/envvar/EnvironmentVariableManager.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/envvar/EnvironmentVariableManager.java
index 23d5b6e2e1f..2f8ed695264 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/envvar/EnvironmentVariableManager.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/envvar/EnvironmentVariableManager.java
@@ -457,12 +457,24 @@ public class EnvironmentVariableManager implements IEnvironmentVariableManager {
 			case IEnvironmentVariable.ENVVAR_REPLACE:
 				env.put(name, var.getValue());
 				break;
-			case IEnvironmentVariable.ENVVAR_APPEND:
-				env.put(name, env.get(name) + var.getDelimiter() + var.getValue());
+			case IEnvironmentVariable.ENVVAR_APPEND: {
+				String oldValue = env.get(name);
+				if (oldValue == null) {
+					env.put(name, var.getValue());
+				} else {
+					env.put(name, oldValue + var.getDelimiter() + var.getValue());
+				}
 				break;
-			case IEnvironmentVariable.ENVVAR_PREPEND:
-				env.put(name, var.getValue() + var.getDelimiter() + env.get(name));
+			}
+			case IEnvironmentVariable.ENVVAR_PREPEND: {
+				String oldValue = env.get(name);
+				if (oldValue == null) {
+					env.put(name, var.getValue());
+				} else {
+					env.put(name, var.getValue() + var.getDelimiter() + oldValue);
+				}
 				break;
+			}
 			case IEnvironmentVariable.ENVVAR_REMOVE:
 				env.remove(name);
 				break;