…uction (dotnet#124977) After PR dotnet#123830 introduced the `jitshared/` directory, `assert` in JIT (and interpreter) code was silently falling through to the C runtime's `assert`, causing dialog popups on assertion failures instead of using `assertAbort`. ## Root Cause The JIT sets up `assert → assertAbort` in `host.h`, which `alloc.h` includes before the jitshared headers. However, three files in `jitshared/` included `<assert.h>`/`<cassert>` directly, which unconditionally redefined `assert` back to the C runtime version — clobbering the JIT's custom handler: - `arenaallocator.h` — `#include <assert.h>` - `compallocator.h` — `#include <assert.h>` - `histogram.cpp` — `#include <cassert>` The interpreter had a related issue: `histogram.cpp` (compiled as part of the interpreter without a PCH) had no `assert` definition at all after removing `#include <cassert>`, since the interpreter doesn't use a precompiled header to supply it. ## Changes - **`jitshared/arenaallocator.h`**, **`jitshared/compallocator.h`**: Remove `#include <assert.h>`. The correct `assert` is now provided by `jitassert.h` via `jitshared.h`. - **`jitshared/histogram.cpp`**: Remove `#include <cassert>` — `jitassert.h` (included via `histogram.h`) now supplies the correct definition. - **`jitshared/jitassert.h`** *(new)*: Shared header that declares `assertAbort` (with `ANALYZER_NORETURN`) and defines `assert` to use it in DEBUG builds, or `((void)0)` in release builds. This is the single source of truth for the assert API shared between JIT and interpreter. - **`jitshared/jitshared.h`**: Include `jitassert.h` so all jitshared code that goes through `jitshared.h` automatically gets the correct `assert`. - **`jitshared/histogram.h`**: Include `jitassert.h` directly, so `histogram.cpp` in the interpreter build (which doesn't go through `jitshared.h`) also gets the correct `assert`. - **`interpreter/interpreter.h`**: Reverted to original include order (`compiler.h` before the `assertAbort` block) — jitshared code now correctly gets `assert` from `jitassert.h` via the jitshared include chain, making the ordering no longer relevant.  <details> <summary>Original prompt</summary> > > ---- > > *This section details on the original issue you should resolve* > > <issue_title>JIT `assert` resolves to C runtime assert</issue_title> > <issue_description>It seems after dotnet#123830 `assert` in the JIT ends up calling into the C runtime's assert, popping open a dialog when it fails. > > cc @dotnet/jit-contrib @davidwrighton </issue_description> > > ## Comments on the Issue (you are @copilot in this section) > > <comments> > </comments> > </details>  - Fixes dotnet#124954  --- 💬 We'd love your input! Share your thoughts on Copilot coding agent in our [2 minute survey](https://gh.io/copilot-coding-agent-survey). --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: davidwrighton <10779849+davidwrighton@users.noreply.github.com>

JIT assert resolves to C runtime assert #124954

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JIT `assert` resolves to C runtime assert #124954