Fix incorrect CAST text->numeric if valid prefix is 1 char long

core/vdbe/mod.rs

@@ -3671,14 +3671,17 @@ fn affinity(datatype: &str) -> Affinity {
 /// The CAST operator understands decimal integers only — conversion of hexadecimal integers stops at the "x" in the "0x" prefix of the hexadecimal integer string and thus result of the CAST is always zero.
 fn cast_text_to_integer(text: &str) -> OwnedValue {
     let text = text.trim();
+    if text.is_empty() {
+        return OwnedValue::Integer(0);
+    }
     if let Ok(i) = text.parse::<i64>() {
         return OwnedValue::Integer(i);
     }
     // Try to find longest valid prefix that parses as an integer
     // TODO: inefficient
-    let mut end_index = text.len() - 1;
-    while end_index > 0 {
-        if let Ok(i) = text[..=end_index].parse::<i64>() {
+    let mut end_index = text.len().saturating_sub(1) as isize;
+    while end_index >= 0 {
+        if let Ok(i) = text[..=end_index as usize].parse::<i64>() {
             return OwnedValue::Integer(i);
         }
         end_index -= 1;
@@ -3692,14 +3695,17 @@ fn cast_text_to_integer(text: &str) -> OwnedValue {
 /// If there is no prefix that can be interpreted as a real number, the result of the conversion is 0.0.
 fn cast_text_to_real(text: &str) -> OwnedValue {
     let trimmed = text.trim_start();
+    if trimmed.is_empty() {
+        return OwnedValue::Float(0.0);
+    }
     if let Ok(num) = trimmed.parse::<f64>() {
         return OwnedValue::Float(num);
     }
     // Try to find longest valid prefix that parses as a float
     // TODO: inefficient
-    let mut end_index = trimmed.len() - 1;
-    while end_index > 0 {
-        if let Ok(num) = trimmed[..=end_index].parse::<f64>() {
+    let mut end_index = trimmed.len().saturating_sub(1) as isize;
+    while end_index >= 0 {
+        if let Ok(num) = trimmed[..=end_index as usize].parse::<f64>() {
             return OwnedValue::Float(num);
         }
         end_index -= 1;

testing/scalar-functions.test

@@ -739,6 +739,7 @@ do_execsql_test zeroblob-blob {
 } {1}
 
 # CAST tests - INTEGER affinity
+
 do_execsql_test cast-text-to-integer {
   SELECT CAST('123' AS INTEGER);
 } {123}
@@ -747,6 +748,10 @@ do_execsql_test cast-text-with-spaces-to-integer {
   SELECT CAST('  123  ' AS INTEGER);
 } {123}
 
+do_execsql_test cast-text-with-trailing-junk-to-integer {
+  SELECT CAST('1abc' AS INTEGER);
+} {1}
+
 do_execsql_test cast-invalid-text-to-integer {
   SELECT CAST('abc' AS INTEGER);
 } {0}