From 0cfba897b8863a48f93a20588d410a00f692524b Mon Sep 17 00:00:00 2001
From: NeilBrown <neil@brown.name>
Date: Mon, 19 Feb 2018 17:08:11 +1100
Subject: [PATCH] oceani: track where each variable was declared.

This allows better error messages when they are
redeclared.

Signed-off-by: NeilBrown <neil@brown.name>
---
 csrc/oceani.mdc | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/csrc/oceani.mdc b/csrc/oceani.mdc
index 4689a52..10ac4ff 100644
--- a/csrc/oceani.mdc
+++ b/csrc/oceani.mdc
@@ -663,6 +663,7 @@ cannot nest, so a declaration while a name is in-scope is an error.
 		struct variable *previous;
 		struct value val;
 		struct binding *name;
+		struct exec *where_decl;// where name was declared
 		struct exec *where_set;	// where type was set
 		## variable fields
 	};
@@ -895,7 +896,7 @@ all pending-scope variables become conditionally scoped.
 
 		switch (v ? v->scope : OutScope) {
 		case InScope:
-			/* Signal error ... once I build error signalling support */
+			/* Caller will report the error */
 			return NULL;
 		case CondScope:
 			for (;
@@ -1378,12 +1379,32 @@ link to find the primary instance.
 		struct variable *v = var_decl(config2context(config), $1.txt);
 		$0 = new_pos(var, $1);
 		$0->var = v;
+		if (v)
+			v->where_decl = $0;
+		else {
+			v = var_ref(config2context(config), $1.txt);
+			$0->var = v;
+			type_err(config2context(config), "error: variable '%v' redeclared",
+			         $0, Vnone, Vnone);
+			type_err(config2context(config), "info: this is where '%v' was first declared",
+			         v->where_decl, Vnone, Vnone);
+		}
 	} }$
 	    | IDENTIFIER ::= ${ {
 		struct variable *v = var_decl(config2context(config), $1.txt);
-		v->constant = 1;
 		$0 = new_pos(var, $1);
 		$0->var = v;
+		if (v) {
+			v->where_decl = $0;
+			v->constant = 1;
+		} else {
+			v = var_ref(config2context(config), $1.txt);
+			$0->var = v;
+			type_err(config2context(config), "error: variable '%v' redeclared",
+			         $0, Vnone, Vnone);
+			type_err(config2context(config), "info: this is where '%v' was first declared",
+			         v->where_decl, Vnone, Vnone);
+		}
 	} }$
 
 	Variable -> IDENTIFIER ${ {
@@ -1446,9 +1467,9 @@ link to find the primary instance.
 			return type;
 		}
 		if (!vtype_compat(type, v->val.vtype, bool_permitted)) {
-			type_err(c, "error: expected %1 but variable %v is %2", prog,
+			type_err(c, "error: expected %1 but variable '%v' is %2", prog,
 			         type, v->val.vtype);
-			type_err(c, "info: this is where %v was set to %1", v->where_set,
+			type_err(c, "info: this is where '%v' was set to %1", v->where_set,
 			         v->val.vtype, Vnone);
 			*ok = 0;
 		}
@@ -2195,7 +2216,7 @@ it is declared, and error will be raised as the name is created as
 		if (t > Vunknown) {
 			if (propagate_types(b->right, c, ok, t, 0) != t)
 				if (b->left->type == Xvar)
-					type_err(c, "info: variable %v was set as %1 here.",
+					type_err(c, "info: variable '%v' was set as %1 here.",
 					         cast(var, b->left)->var->where_set, t, Vnone);
 		} else {
 			t = propagate_types(b->right, c, ok, Vnolabel, 0);
-- 
2.43.0