libutil: remove the interrupt-blocking code

The interrupt-blocking code was originally introduced 20 years ago so that
trying to log an error message does not result in an interrupt exception being
thrown and then going unhandled (c8d3882cdc8f9e22c58af285c1996265c1af75d5).
However, the logging code does not check for interrupts any more
(054be5025762c5e1c7e853c4fa5d7eed8da1727f), so this reasoning is no longer
applicable. Delete this code so that later interrupts are unblocked again, for
example in the next line entered into the repl.

Closes: https://git.lix.systems/lix-project/lix/issues/296
Change-Id: I48253f5f4272e75001148c13046e709ef5427fbd

3 files changed, 2 insertions, 20 deletions

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 9d4dd41ed..96ecbac8f 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -320,16 +320,7 @@ int handleExceptions(const std::string & programName, std::function<void()> fun)
 
     std::string error = ANSI_RED "error:" ANSI_NORMAL " ";
     try {
-        try {
-            fun();
-        } catch (...) {
-            /* Subtle: we have to make sure that any `interrupted'
-               condition is discharged before we reach printMsg()
-               below, since otherwise it will throw an (uncaught)
-               exception. */
-            setInterruptThrown();
-            throw;
-        }
+        fun();
     } catch (Exit & e) {
         return e.status;
     } catch (UsageError & e) {
diff --git a/src/libutil/signals.cc b/src/libutil/signals.cc
index f5c79b325..41fdc9dc8 100644
--- a/src/libutil/signals.cc
+++ b/src/libutil/signals.cc
@@ -9,21 +9,14 @@ namespace nix {
 
 std::atomic<bool> _isInterrupted = false;
 
-static thread_local bool interruptThrown = false;
 thread_local std::function<bool()> interruptCheck;
 
-void setInterruptThrown()
-{
-    interruptThrown = true;
-}
-
 void _interrupted()
 {
     /* Block user interrupts while an exception is being handled.
        Throwing an exception while another exception is being handled
        kills the program! */
-    if (!interruptThrown && !std::uncaught_exceptions()) {
-        interruptThrown = true;
+    if (!std::uncaught_exceptions()) {
         throw Interrupted("interrupted by the user");
     }
 }
diff --git a/src/libutil/signals.hh b/src/libutil/signals.hh
index c58dc37cf..71593df95 100644
--- a/src/libutil/signals.hh
+++ b/src/libutil/signals.hh
@@ -22,8 +22,6 @@ extern std::atomic<bool> _isInterrupted;
 
 extern thread_local std::function<bool()> interruptCheck;
 
-void setInterruptThrown();
-
 void _interrupted();
 
 void inline checkInterrupt()