[vala] Report error on duplicate switch label

[Jürg Billeter <juergbi src gnome org>]

commit fea88bd2074321eb20881357984290e94fb31e72
Author: Luca Bruno <lethalman88 gmail com>
Date:   Mon Mar 8 23:36:51 2010 +0100

    Report error on duplicate switch label
    
    Fixes bug 572556.

 vala/valaswitchstatement.vala |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)
---
diff --git a/vala/valaswitchstatement.vala b/vala/valaswitchstatement.vala
index eb038bb..00a8b8f 100644
--- a/vala/valaswitchstatement.vala
+++ b/vala/valaswitchstatement.vala
@@ -116,9 +116,24 @@ public class Vala.SwitchStatement : CodeNode, Statement {
 		// ensure that possibly owned (string) expression stays alive
 		expression.target_type = expression.value_type.copy ();
 
+		var labelset = new HashSet<string> (str_hash, str_equal);
 		foreach (SwitchSection section in sections) {
 			section.check (analyzer);
 
+			// check for duplicate literal case labels
+			// FIXME: make it work for all constant expressions
+			foreach (SwitchLabel label in section.get_labels ()) {
+				string? value = null;
+				if (label.expression is StringLiteral) {
+					value = ((StringLiteral)label.expression).eval ();
+				} else if (label.expression is Literal) {
+					value = ((Literal)label.expression).to_string ();
+				}
+
+				if (value != null && !labelset.add (value)) {
+					Report.error (label.expression.source_reference, "Switch statement already contains this label");
+				}
+			}
 			add_error_types (section.get_error_types ());
 		}