Possible regression

[bk322]

I get an out of memory error on master, but the same script works on the same data using regex_replace build with commit of 2020-Nov-18: https://github.com/gwenn/sqlite-regex-replace-ext/tree/458fe6978349b503095ed7a5ecf637f0b0ec4d38

Here's a minimal working example:
out-of-memory.zip

It contains:

data.csv
libSqlite3Icu.so
libSqlite3IcuReplace-458fe6978349b503095ed7a5ecf637f0b0ec4d38.so
libSqlite3IcuReplace-master.so
script-458fe6978349b503095ed7a5ecf637f0b0ec4d38.sql
script-master.sql

When I run

sqlite3 < script-458fe6978349b503095ed7a5ecf637f0b0ec4d38.sql 

it works, when I run

sqlite3 < script-master.sql

it gives out of memory error:

The two sql scripts differ only with the regex_replace extension:

-- -*- mode: sql -*-

.load ./libSqlite3Icu.so

-- https://github.com/gwenn/sqlite-regex-replace-ext/tree/master - gives out of memory:
.load ./libSqlite3IcuReplace-master.so

.mode      csv
.separator ',' "\n"
.header    on

.import data.csv data

select
  case regex_replace(' \(.+', "column", '')
    when 'foo' then 'bar'
    else ''
  end as "column no comments"
from data
;

Both scripts run on the latest sqlite (3.35.4), I think regression is introduced by the February commits to this repo:
https://github.com/gwenn/sqlite-regex-replace-ext/commits/master

[gwenn]

sqlite> .load ./icu_replace.so
sqlite> .mode      csv
sqlite> .separator ',' "\n"
sqlite> .header    on
sqlite> .import data.csv data
sqlite> .log stdout
sqlite> select case regex_replace(' \(.+', "column", '') when 'foo' then 'bar' else '' end as "column no comments" from data;
...
(0) zInput: '', nOut: 0
(7) statement aborts at 4: [select case regex_replace(' \(.+', "column", '') when 'foo' then 'bar' else '' end as "column no comments" from data;]
Error: out of memory
sqlite>

[gwenn]

diff --git a/icu_replace.c b/icu_replace.c
index b68315a..835c0a3 100644
--- a/icu_replace.c
+++ b/icu_replace.c
@@ -94,6 +94,13 @@ static void icuReplaceAllFunc(
   }
   /* Expect output length = input length. */
   nOut = sqlite3_value_bytes16(argv[1]);
+  if( nOut==0 ){ // or output length = remplacement length
+    nOut = sqlite3_value_bytes16(argv[2]);
+  }
+  if( nOut==0 ){ // if both input and replacement are empty
+    sqlite3_result_text16(context, "", 0, SQLITE_STATIC);
+    return;
+  }
 /*
   int32_t   uregex_replaceAll (URegularExpression *regexp, const UChar *replacementText, int32_t replacementLength, UChar *destBuf, int32_t destCapacity, UErrorCode *status)
 */

[bk322]

@gwenn, yes that works.

[gwenn]

@bk322 Thanks for the detailed issue