From 05ead8c40dc12a058ff10d9df088dc83b6edbf67 Mon Sep 17 00:00:00 2001
From: Dianne Skoll <dianne@skoll.ca>
Date: Thu, 30 Oct 2025 14:30:29 -0400
Subject: [PATCH] More helpful errors when parsing expressions.

---
 src/err.h      |  2 ++
 src/expr.c     | 14 +++++++++++++-
 tests/test.cmp | 14 +++++++++-----
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/err.h b/src/err.h
index 17bdca43..dc32001a 100644
--- a/src/err.h
+++ b/src/err.h
@@ -137,6 +137,7 @@
 #define E_NO_MB             113
 #define E_BAD_MB_SEQ        114
 #define E_EXPR_NODES_EXCEEDED 115
+#define E_EXPECTING_EOXPR   116
 #ifdef MK_GLOBALS
 #undef EXTERN
 #define EXTERN
@@ -270,6 +271,7 @@ EXTERN char *ErrMsg[]
 /* E_NO_MB */              "C library does not support multibyte characters",
 /* E_BAD_MB_SEQ */         "Invalid multibyte sequence",
 /* E_EXPR_NODES_EXCEEDED */ "Maximum expression complexity exceeded",
+/* E_EXPECTING_EOXPR */    "Expecting end-of-expression",
 }
 #endif /* MK_GLOBALS */
 ;
diff --git a/src/expr.c b/src/expr.c
index 0d3d5f36..1940eb7a 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -2759,9 +2759,20 @@ expr_node *parse_expression(char const **e, int *r, Var *locals)
             print_expr_tree(node, ErrFp);
             fprintf(ErrFp, "\n");
         }
-        if (**e && (**e != ']')) {
+    }
+    if (**e && (**e != ']')) {
+        if (DebugFlag & DB_PARSE_EXPR) {
             fprintf(ErrFp, "  Unparsed: %s\n", *e);
         }
+        if (*r == OK) {
+            *r = E_EXPECTING_EOXPR;
+        }
+    }
+    if (*r != OK) {
+        if (node) {
+            free_expr_tree(node);
+            node = NULL;
+        }
     }
     if (!SuppressErrorOutputInCatch) {
         if (*r == E_EXPECT_COMMA     ||
@@ -2771,6 +2782,7 @@ expr_node *parse_expression(char const **e, int *r, Var *locals)
             *r == E_2FEW_ARGS        ||
             *r == E_PARSE_ERR        ||
             *r == E_EOLN             ||
+            *r == E_EXPECTING_EOXPR  ||
             *r == E_BAD_NUMBER       ||
             *r == E_BAD_DATE         ||
             *r == E_BAD_TIME         ||
diff --git a/tests/test.cmp b/tests/test.cmp
index 33dfd2e9..b24d0a0d 100644
--- a/tests/test.cmp
+++ b/tests/test.cmp
@@ -5040,8 +5040,9 @@ set a 7 * "Cabbage! "
 
 # Should result in errors
 set pqxya 1+2)
-1 + 2 => 3
-../tests/test.rem(1014): Expecting end-of-line
+1+2)
+   ^-- here
+../tests/test.rem(1014): Expecting end-of-expression
 
 # Should result in an error
 REM Tue OMIT 2024-01-01 MSG Wookie
@@ -16669,7 +16670,7 @@ Expression nodes high-water: 302076
     Expression nodes leaked: 0
      Parse level high-water: 34
 Max expr node evaluations per line: 2001
-Total expression node evaluations:  106467
+Total expression node evaluations:  106464
 
 Test 2
 
@@ -23905,7 +23906,9 @@ Parsed expression: 1||1
 Parsed expression: 2
   => 2
   Unparsed: , 3
-../tests/expr.rem(15): Expecting end-of-line
+, 3
+ ^-- here
+../tests/expr.rem(15): Expecting end-of-expression
 Parsed expression: iif(0, "foo", 0, "bar", 1, "blech", 0, "quux", 1, "borhy", "wacka")
   => (Iif 0 "foo" 0 "bar" 1 "blech" 0 "quux" 1 "borhy" "wacka")
 iif(0, ?, 0, ?, 1, "blech", ?, ?, ?, ?, ?) => "blech"
@@ -24284,7 +24287,7 @@ Expression nodes high-water: 499
     Expression nodes leaked: 0
      Parse level high-water: 2001
 Max expr node evaluations per line: 499
-Total expression node evaluations:  632
+Total expression node evaluations:  631
 -stdin-(14): Unmatched PUSH-OMIT-CONTEXT at -stdin-(7)
 -stdin-(14): Warning: PUSH-OMIT-CONTEXT without matching POP-OMIT-CONTEXT
 No reminders.
@@ -25063,6 +25066,7 @@ TRANSLATE "TZ specified for non-timed reminder" ""
 TRANSLATE "C library does not support multibyte characters" ""
 TRANSLATE "Invalid multibyte sequence" ""
 TRANSLATE "Maximum expression complexity exceeded" ""
+TRANSLATE "Expecting end-of-expression" ""
 
 # Other Messages
 TRANSLATE "%s function `%s' defined at %s(%s) does not use its argument" ""