From 335e13251ef5d07a3a41fe26199ad7c7b34a9fa1 Mon Sep 17 00:00:00 2001
From: Kevin Backhouse <kevinbackhouse@github.com>
Date: Sun, 23 Oct 2022 15:14:09 +0100
Subject: [PATCH] Add #error so the build fails if mmap isn't supported.

---
 src/basicio.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/basicio.cpp b/src/basicio.cpp
index 5916addc..5d1c342b 100644
--- a/src/basicio.cpp
+++ b/src/basicio.cpp
@@ -203,6 +203,7 @@ int FileIo::munmap() {
     CloseHandle(p_->hFile_);
     p_->hFile_ = 0;
 #else
+#error Platforms without mmap are not supported. See https://github.com/Exiv2/exiv2/issues/2380
     if (p_->isWriteable_) {
       seek(0, BasicIo::beg);
       write(p_->pMappedArea_, p_->mappedLength_);
@@ -275,6 +276,7 @@ byte* FileIo::mmap(bool isWriteable) {
   }
   p_->pMappedArea_ = static_cast<byte*>(rc);
 #else
+#error Platforms without mmap are not supported. See https://github.com/Exiv2/exiv2/issues/2380
   // Workaround for platforms without mmap: Read the file into memory
   byte* buf = new byte[p_->mappedLength_];
   const long offset = std::ftell(p_->fp_);