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Fix delegate not being cleared by assigning empty braces

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Fixes issue #1399.

The non-capturing lambda support (PR#1295) added a non-explicit
delegate(function_ptr) constructor and operator=(function_ptr). This
caused `delegate = {}` to implicitly convert `{}` to a null function
pointer and bind it via function_ptr_stub, leaving the delegate
appearing valid (stub != nullptr) but invoking through a null pointer
(undefined behavior).

Fix:
- Mark delegate(function_ptr) constructor explicit to prevent implicit
  conversion from `{}` during initialization.
- In operator=(function_ptr), clear the delegate when fp is null
  instead of binding a null pointer through function_ptr_stub.

Added tests verifying that both `delegate d = {}` and `d = {}` produce
an invalid (cleared) delegate.
This commit is contained in:
Roland Reichwein 2026-04-20 12:46:09 +02:00
parent bbf74c5334
commit 53b3b3702f
2 changed files with 30 additions and 2 deletions
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11
include/etl/private/delegate_cpp11.h
View File

@ -172,7 +172,7 @@ namespace etl
//*************************************************************************
// Construct from a function pointer.
//*************************************************************************
delegate(function_ptr fp) ETL_NOEXCEPT
explicit delegate(function_ptr fp) ETL_NOEXCEPT
{
assign(fp, function_ptr_stub);
}
@ -534,7 +534,14 @@ namespace etl
//*************************************************************************
delegate& operator=(function_ptr fp) ETL_NOEXCEPT
{
assign(fp, function_ptr_stub);
if (fp == ETL_NULLPTR)
{
invocation.clear();
}
else
{
assign(fp, function_ptr_stub);
}
return *this;
}

21
test/test_delegate.cpp
View File

@ -372,6 +372,27 @@ namespace
CHECK_FALSE(d.is_valid());
}
//*************************************************************************
TEST_FIXTURE(SetupFixture, test_is_valid_after_init_empty_braces)
{
etl::delegate<void(void)> d = {};
CHECK_FALSE(d.is_valid());
}
//*************************************************************************
TEST_FIXTURE(SetupFixture, test_is_valid_after_assign_empty_braces)
{
auto lambda = [] {
};
etl::delegate<void(void)> d(lambda);
CHECK_TRUE(d.is_valid());
d = {};
CHECK_FALSE(d.is_valid());
}
//*************************************************************************
TEST_FIXTURE(SetupFixture, test_free_void)
{