py/vstr: Remove vstr.had_error flag and inline basic vstr functions.

The vstr.had_error flag was a relic from the very early days which assumed
that the malloc functions (eg m_new, m_renew) returned NULL if they failed
to allocate.  But that's no longer the case: these functions will raise an
exception if they fail.

Since it was impossible for had_error to be set, this patch introduces no
change in behaviour.

An alternative option would be to change the malloc calls to the _maybe
variants, which return NULL instead of raising, but then a lot of code
will need to explicitly check if the vstr had an error and raise if it
did.

The code-size savings for this patch are, in bytes: bare-arm:188,
minimal:456, unix(NDEBUG,x86-64):368, stmhal:228, esp8266:360.

1 files changed, 2 insertions, 1 deletions

diff --git a/py/lexer.c b/py/lexer.c
index 820f91be78..b2c9c5ff78 100644
--- a/py/lexer.c
+++ b/py/lexer.c
@@ -723,7 +723,8 @@ mp_lexer_t *mp_lexer_new(qstr src_name, void *stream_data, mp_lexer_stream_next_
     vstr_init(&lex->vstr, 32);
 
     // check for memory allocation error
-    if (lex->indent_level == NULL || vstr_had_error(&lex->vstr)) {
+    // note: vstr_init above may fail on malloc, but so may mp_lexer_next_token_into below
+    if (lex->indent_level == NULL) {
         mp_lexer_free(lex);
         return NULL;
     }