Merge changes I8456c47b,I48253f5f into main

* changes:
  repl: clear the interrupt before reading the next line
  libutil: remove the interrupt-blocking code

doc/manual/rl-next/repl-interrupt.md

@@ -0,0 +1,8 @@
+---
+synopsis: Interrupting builds in the REPL works more than once
+cls: 1097
+---
+
+Builds in the REPL can be interrupted by pressing Ctrl+C.
+Previously, this only worked once per REPL session; further attempts would be ignored.
+This issue is now fixed, so that builds can be canceled consistently.

src/libcmd/repl.cc

@@ -262,6 +262,8 @@ ReplExitStatus NixRepl::mainLoop()
     std::string input;
 
     while (true) {
+        _isInterrupted = false;
+
         // When continuing input from previous lines, don't print a prompt, just align to the same
         // number of chars as the prompt.
         if (!interacter->getLine(input, input.empty() ? ReplPromptType::ReplPrompt : ReplPromptType::ContinuationPrompt)) {
@@ -424,8 +426,6 @@ ProcessLineResult NixRepl::processLine(std::string line)
     if (line.empty())
         return ProcessLineResult::PromptAgain;
 
-    _isInterrupted = false;
-
     std::string command, arg;
 
     if (line[0] == ':') {

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) {

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");
     }
 }

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()