Split ignoreException to avoid suppressing CTRL-C

This splits `ignoreException` into `ignoreExceptionExceptInterrupt`
(which ignores all exceptions except `Interrupt`, which indicates a
SIGINT/CTRL-C) and `ignoreExceptionInDestructor` (which ignores all
exceptions, so that destructors do not throw exceptions).

This prevents many cases where Nix ignores CTRL-C entirely.
See: https://github.com/NixOS/nix/issues/7245

Upstream-PR: https://github.com/NixOS/nix/pull/11618
Change-Id: Ie7d2467eedbe840d1b9fa2e88a4e88e4ab26a87b

src/libutil/error.cc

@@ -4,6 +4,7 @@
 #include "position.hh"
 #include "terminal.hh"
 #include "strings.hh"
+#include "signals.hh"
 
 #include <iostream>
 #include <optional>
@@ -416,7 +417,7 @@ std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool s
     return out;
 }
 
-void ignoreException(Verbosity lvl)
+void ignoreExceptionInDestructor(Verbosity lvl)
 {
     /* Make sure no exceptions leave this function.
        printError() also throws when remote is closed. */
@@ -429,4 +430,15 @@ void ignoreException(Verbosity lvl)
     } catch (...) { }
 }
 
+void ignoreExceptionExceptInterrupt(Verbosity lvl)
+{
+    try {
+        throw;
+    } catch (const Interrupted & e) {
+        throw;
+    } catch (std::exception & e) {
+        printMsg(lvl, "error (ignored): %1%", e.what());
+    }
+}
+
 }