config: Replace ~ with user's home directory path

config.go

@@ -352,6 +352,10 @@ func (c *Config) getMatchingHosts(alias string) []*Host {
 	return matchingHosts
 }
 
+func substituteTildeForHomeDirectory(value string) string {
+	return strings.Replace(value, "~", homedir(), 1)
+}
+
 func getKeyFromNodeForHost(node Node, alias, key string) (string, bool) {
 	lowerKey := strings.ToLower(key)
 	switch t := node.(type) {
@@ -363,12 +367,12 @@ func getKeyFromNodeForHost(node Node, alias, key string) (string, bool) {
 			panic("can't handle Match directives")
 		}
 		if lkey == lowerKey {
-			return t.Value, true
+			return substituteTildeForHomeDirectory(t.Value), true
 		}
 	case *Include:
 		val := t.Get(alias, key)
 		if val != "" {
-			return val, true
+			return substituteTildeForHomeDirectory(val), true
 		}
 	}
 	return "", false

config_test.go

@@ -349,6 +349,34 @@ func TestIncludeString(t *testing.T) {
 	}
 }
 
+func TestResolvesTilde(t *testing.T) {
+	us := &UserSettings{
+		userConfigFinder: testConfigFinder("testdata/configwithtilde"),
+	}
+
+	hosts := []string {
+		"specifc",
+		"unknown",
+	}
+
+	for _, host := range hosts {
+		t.Run(host, func(t *testing.T) {
+			val, err := us.GetStrict(host, "IdentityAgent")
+			if err != nil {
+				t.Errorf("expected nil error, got %v", err)
+			}
+
+			if !strings.Contains(val, homedir()) {
+				t.Errorf("expected value to have replaced ~ with user's home directory path, got %q", val)
+			}
+
+			if strings.Contains(val, "~/") {
+				t.Errorf("expected ~/ to have been replaced with user's home directory path, got %q", val)
+			}
+		})
+	}
+}
+
 var shellIncludeFile = []byte(`
 # This host should not exist, so we can use it for test purposes / it won't
 # interfere with any other configurations.

testdata/configwithtilde

@@ -0,0 +1,5 @@
+Host specific
+IdentityAgent "~/specific.sock"
+
+Host *
+	IdentityAgent "~/wildcard.sock"