Goto statements with a bad label produces error message.

Now it also produces a short list of suggestions based on string distance.

ctx.cpp

@@ -1155,6 +1155,19 @@ FunctionEmitContext::GetLabeledBasicBlock(const std::string &label) {
         return NULL;
 }
 
+std::vector<std::string>
+FunctionEmitContext::GetLabels() {
+    // Initialize vector to the right size
+    std::vector<std::string> labels(labelMap.size());
+
+    // Iterate through labelMap and grab only the keys
+    std::map<std::string, llvm::BasicBlock*>::iterator iter;
+    for (iter=labelMap.begin(); iter != labelMap.end(); iter++)
+        labels.push_back(iter->first);
+
+    return labels;
+}
+
 
 void
 FunctionEmitContext::CurrentLanesReturned(Expr *expr, bool doCoherenceCheck) {

ctx.h

@@ -248,6 +248,10 @@ public:
         new basic block that it starts. */
     llvm::BasicBlock *GetLabeledBasicBlock(const std::string &label);
 
+    /** Returns a vector of all labels in the context. This is
+        simply the key set of the labelMap */
+    std::vector<std::string> GetLabels();
+
     /** Called to generate code for 'return' statement; value is the
         expression in the return statement (if non-NULL), and
         doCoherenceCheck indicates whether instructions should be generated

stmt.cpp

@@ -2281,10 +2281,26 @@ GotoStmt::EmitCode(FunctionEmitContext *ctx) const {
 
     llvm::BasicBlock *bb = ctx->GetLabeledBasicBlock(label);
     if (bb == NULL) {
-        // TODO: use the string distance stuff to suggest alternatives if
-        // there are some with names close to the label name we have here..
-        Error(identifierPos, "No label named \"%s\" found in current function.",
+        /* Label wasn't found. Emit an error */
+        Error(identifierPos, 
+                "No label named \"%s\" found in current function.",
               label.c_str());
+
+        /* Look for suggestions that are close */
+        std::vector<std::string> labels = ctx->GetLabels();
+        std::vector<std::string> matches = MatchStrings(label, labels);
+        if (! matches.empty()) {
+            /* Print up to 5 matches. Don't want to spew too much */
+            std::string match_output("Did you mean\n");
+            for (unsigned int i=0; i<matches.size() && i<5; i++)
+                match_output += " " + matches[i] + "?\n";
+
+            /*TODO. Embed these suggestions IN the error message
+               itself. Currently it looks ugly since line breaks
+               are ignored inside Error() strings. Multiple
+               Error() messages are not an option either */
+            printf("%s", match_output.c_str());
+        }
         return;
     }
 

tests_errors/goto-5.ispc

@@ -0,0 +1,6 @@
+
+void func(int x) {
+completelydifferentlabel:
+    goto label;
+}
+

tests_errors/goto-6.ispc

@@ -0,0 +1,9 @@
+
+void func(int x) {
+libel:
+babel:
+lbel:
+label2:
+    goto label;
+}
+