Fix potential infinite loops in generators combined with section filter

The problem was that under specific circumstances, namely that none
of their children progressed, `GeneratorTracker` will not progress.
This was changed recently, to allow for code like this, where a
`SECTION` follows a `GENERATE` at the same level:

```cpp
SECTION("A") {}
auto a = GENERATE(1, 2);
SECTION("B") {}
```

However, this interacted badly with `SECTION` filters (`-c foo`),
as they could deactivate all `SECTION`s below a generator, and thus
stop it from progressing forever. This commit makes GeneratorTracker
check whether there are any filters active, and if they are, it checks
whether its section-children can ever run.

Fixes #2025

tests/SelfTest/UsageTests/Tricky.tests.cpp

@@ -13,6 +13,8 @@
 #endif
 
 #include <catch2/catch_test_macros.hpp>
+#include <catch2/generators/catch_generators.hpp>
+#include <catch2/generators/catch_generators_range.hpp>
 
 #include <cstdio>
 #include <sstream>
@@ -399,3 +401,28 @@ TEST_CASE("#1514: stderr/stdout is not captured in tests aborted by an exception
     // FAIL aborts the test by throwing a Catch exception
     FAIL("1514");
 }
+
+
+TEST_CASE( "#2025: -c shouldn't cause infinite loop", "[sections][generators][regression][.approvals]" ) {
+    SECTION( "Check cursor from buffer offset" ) {
+        auto bufPos = GENERATE_REF( range( 0, 44 ) );
+        WHEN( "Buffer position is " << bufPos ) { REQUIRE( 1 == 1 ); }
+    }
+}
+
+TEST_CASE("#2025: original repro", "[sections][generators][regression][.approvals]") {
+    auto fov = GENERATE(true, false);
+    DYNAMIC_SECTION("fov_" << fov) {
+        std::cout << "inside with fov: " << fov << '\n';
+    }
+}
+
+TEST_CASE("#2025: same-level sections", "[sections][generators][regression][.approvals]") {
+    SECTION("A") {
+        SUCCEED();
+    }
+    auto i = GENERATE(1, 2, 3);
+    SECTION("B") {
+        REQUIRE(i < 4);
+    }
+}