[opt] Error on `opt -O# --foo-pass`

[aeubanks]

Summary

Matches the error message we emit with -opt -O# --passes=foo.
Otherwise we crash later on.

Makes #55320 much less confusing.

[MaskRay]

LGTM.

llvm/test/Other/opt-On.ll

 ; RUN: not opt -O1 -O2 < %s 2>&1 | FileCheck %s --check-prefix=MULTIPLE
 ; RUN: not opt -O1 -passes='no-op-module' < %s 2>&1 | FileCheck %s --check-prefix=BOTH
+; RUN: not opt -O1 --gvn < %s 2>&1 | FileCheck %s --check-prefix=BOTH
 ; RUN: opt -O0 < %s -S 2>&1 | FileCheck %s --check-prefix=OPT
 ; RUN: opt -O1 < %s -S 2>&1 | FileCheck %s --check-prefix=OPT
 ; RUN: opt -O2 < %s -S 2>&1 | FileCheck %s --check-prefix=OPT
 ; RUN: opt -O3 < %s -S 2>&1 | FileCheck %s --check-prefix=OPT
 ; RUN: opt -Os < %s -S 2>&1 | FileCheck %s --check-prefix=OPT
 ; RUN: opt -Oz < %s -S 2>&1 | FileCheck %s --check-prefix=OPT
 ; RUN: opt -O2 -debug-pass-manager -disable-output < %s 2>&1 | FileCheck %s --check-prefix=AA
 

llvm/tools/opt/opt.cpp

if (PassPipeline.getNumOccurrences() > 0 && PassList.size() > 0) {
       return 1;
     }
     auto NumOLevel = OptLevelO0 + OptLevelO1 + OptLevelO2 + OptLevelO3 +
                      OptLevelOs + OptLevelOz;
     if (NumOLevel > 1) {
       errs() << "Cannot specify multiple -O#\n";
       return 1;
     }
-    if (NumOLevel > 0 && PassPipeline.getNumOccurrences() > 0) {
-      errs() << "Cannot specify -O# and --passes=, use "
+    if (NumOLevel > 0 &&
+        (PassPipeline.getNumOccurrences() > 0 || PassList.size() > 0)) {
+      errs() << "Cannot specify -O# and --passes=/--foo-pass, use "
                 "-passes='default<O#>,other-pass'\n";
       return 1;
     }
     std::string Pipeline = PassPipeline;
 
     SmallVector<StringRef, 4> Passes;
     if (OptLevelO0)
       Pipeline = "default<O0>";