Support: Fix program error test failures when using fork

The actual exec error will not be immediate in the parent when
using the fork path. The error will manifest on the wait. The
ExecuteNoWait test was also expecting the immediate wait.

I hacked up the exit value ExecutionFailed value in ExecuteAndWait,
although arguably the previous behavior was correct. I'm not sure
what the point of the argument is, it's redundant with the return code.

Fixes #129208

Author: arsenm

llvm/lib/Support/Program.cpp

@@ -45,6 +45,10 @@ int sys::ExecuteAndWait(StringRef Program, ArrayRef<StringRef> Args,
     ProcessInfo Result = Wait(
         PI, SecondsToWait == 0 ? std::nullopt : std::optional(SecondsToWait),
         ErrMsg, ProcStat);
+
+    if (ExecutionFailed && Result.ReturnCode < 0)
+      *ExecutionFailed = true;
+
     return Result.ReturnCode;
   }
 

llvm/unittests/Support/ProgramTest.cpp

@@ -433,10 +433,19 @@ TEST(ProgramTest, TestExecuteNegative) {
     bool ExecutionFailed;
     ProcessInfo PI = ExecuteNoWait(Executable, argv, std::nullopt, {}, 0,
                                    &Error, &ExecutionFailed);
-    EXPECT_EQ(PI.Pid, ProcessInfo::InvalidPid)
-        << "On error ExecuteNoWait should return an invalid ProcessInfo";
-    EXPECT_TRUE(ExecutionFailed);
-    EXPECT_FALSE(Error.empty());
+
+    if (ExecutionFailed) {
+      EXPECT_EQ(PI.Pid, ProcessInfo::InvalidPid)
+          << "On error ExecuteNoWait should return an invalid ProcessInfo";
+      EXPECT_FALSE(Error.empty());
+    } else {
+      std::string WaitErrMsg;
+      EXPECT_NE(PI.Pid, ProcessInfo::InvalidPid);
+      ProcessInfo WaitPI = Wait(PI, std::nullopt, &WaitErrMsg);
+      EXPECT_EQ(WaitPI.Pid, PI.Pid);
+      EXPECT_LT(WaitPI.ReturnCode, 0);
+      EXPECT_FALSE(WaitErrMsg.empty());
+    }
   }
 
 }