shiboken6: Fix increment/decrement operators

For classes that have increment/decrement operators
(++/--), shiboken6 generated operators +=/-= ( __iadd__/__isub__)
by calling them n times. This was mainly intended for iterators.

However, when both operator++/-- and operator+=/-= were present (as
introduced by qtdeclarative/f8f31dd0e1f9425ba272691c79e719ebc4bcfb94
for QJSPrimitiveValue), duplicate code and errors were generated.

This requires filtering of the operator functions.
Introduce a separate function type for increment/decrement operators
and remove them if operators +=/-= were found. Also, when
both prefix and postfix version of the increment/decrement operators
are found, remove one.

Extend existing class IntWrapper from libsample for testing.

Add explanatory comment and use prefix increment.

Pick-to: 6.1
Change-Id: I0f8a0c79a6f74974ba327d21f35fff74962ffd3a
Reviewed-by: Christian Tismer <tismer@stackless.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/sources/shiboken6/ApiExtractor/abstractmetalang.h b/sources/shiboken6/ApiExtractor/abstractmetalang.h
index f83062dd7..daa9eba1e 100644
--- a/sources/shiboken6/ApiExtractor/abstractmetalang.h
+++ b/sources/shiboken6/ApiExtractor/abstractmetalang.h
@@ -166,6 +166,7 @@ public:
     AbstractMetaFunctionCList operatorOverloads(OperatorQueryOptions query) const;
 
     bool hasArithmeticOperatorOverload() const;
+    bool hasIncDecrementOperatorOverload() const;
     bool hasBitwiseOperatorOverload() const;
     bool hasComparisonOperatorOverload() const;
     bool hasLogicalOperatorOverload() const;