diff --git a/include/vast/CodeGen/CodeGen.hpp b/include/vast/CodeGen/CodeGen.hpp
index 4fef413bc0..a38d105f4a 100644
--- a/include/vast/CodeGen/CodeGen.hpp
+++ b/include/vast/CodeGen/CodeGen.hpp
@@ -450,7 +450,7 @@ namespace vast::cg
                     VAST_UNIMPLEMENTED;
                 } else if (body) {
                     if (mlir::failed(build_function_body(body))) {
-                        VAST_UNREACHABLE("failed function body codegen");
+                        VAST_FATAL("failed function body codegen");
                     }
                 } else {
                     VAST_UNIMPLEMENTED_MSG("no definition for emitted function");
diff --git a/include/vast/CodeGen/CodeGenContext.hpp b/include/vast/CodeGen/CodeGenContext.hpp
index 2e91ff53a7..3c53ff352e 100644
--- a/include/vast/CodeGen/CodeGenContext.hpp
+++ b/include/vast/CodeGen/CodeGenContext.hpp
@@ -215,7 +215,7 @@ namespace vast::cg
                 if (const auto *d = llvm::dyn_cast< clang::NamedDecl >(dctx)) {
                     name += get_decl_name(d);
                 } else {
-                    VAST_UNREACHABLE("unknown decl context: {0}", dctx->getDeclKindName());
+                    VAST_FATAL("unknown decl context: {0}", dctx->getDeclKindName());
                 }
 
                 name += "::";
diff --git a/include/vast/CodeGen/CodeGenDeclVisitor.hpp b/include/vast/CodeGen/CodeGenDeclVisitor.hpp
index f1f8560ffc..431b366bf3 100644
--- a/include/vast/CodeGen/CodeGenDeclVisitor.hpp
+++ b/include/vast/CodeGen/CodeGenDeclVisitor.hpp
@@ -185,7 +185,7 @@ namespace vast::cg {
                     return fn;
                 }
 
-                VAST_UNREACHABLE("NYI");
+                VAST_UNIMPLEMENTED;
 
                 // TODO: clang checks here if this is a llvm::GlobalAlias... how will we
                 // support this?
@@ -282,7 +282,7 @@ namespace vast::cg {
                 return fn;
             }
 
-            VAST_UNREACHABLE("codegen of incomplete function");
+            VAST_FATAL("codegen of incomplete function");
         }
 
         vast_function get_addr_of_function(
@@ -486,7 +486,7 @@ namespace vast::cg {
                 case clang::SC_PrivateExtern: return hl::StorageClass::sc_private_extern;
                 case clang::SC_Register: return hl::StorageClass::sc_register;
             }
-            VAST_UNREACHABLE("unknown storage class");
+            VAST_UNIMPLEMENTED_MSG("unknown storage class");
         }
 
         hl::TSClass VisitThreadStorageClass(const clang::VarDecl *decl) const {
@@ -496,7 +496,7 @@ namespace vast::cg {
                 case clang::TSCS_thread_local: return hl::TSClass::tsc_cxx_thread;
                 case clang::TSCS__Thread_local: return hl::TSClass::tsc_c_thread;
             }
-            VAST_UNREACHABLE("unknown storage class");
+            VAST_UNIMPLEMENTED_MSG("unknown thread storage class");
         }
 
         operation VisitVarDecl(const clang::VarDecl *decl) {
@@ -713,7 +713,7 @@ namespace vast::cg {
                 case clang::AccessSpecifier::AS_none:
                     return hl::AccessSpecifier::as_none;
             }
-            VAST_UNREACHABLE("unknown access specifier");
+            VAST_UNIMPLEMENTED_MSG("unknown access specifier");
         }
 
         //
diff --git a/include/vast/CodeGen/CodeGenStmtVisitor.hpp b/include/vast/CodeGen/CodeGenStmtVisitor.hpp
index 8fe8e88354..e684ef52dc 100644
--- a/include/vast/CodeGen/CodeGenStmtVisitor.hpp
+++ b/include/vast/CodeGen/CodeGenStmtVisitor.hpp
@@ -747,7 +747,7 @@ namespace vast::cg {
                 return VisitFunctionDeclRefExpr(expr);
             }
 
-            VAST_UNREACHABLE("unknown underlying declaration to be referenced");
+            VAST_UNIMPLEMENTED_MSG("unknown underlying declaration to be referenced");
         }
 
         Operation *VisitPredefinedExpr(const clang::PredefinedExpr *expr)
diff --git a/include/vast/CodeGen/UnreachableVisitor.hpp b/include/vast/CodeGen/UnreachableVisitor.hpp
index 3088db7fe6..33352daa37 100644
--- a/include/vast/CodeGen/UnreachableVisitor.hpp
+++ b/include/vast/CodeGen/UnreachableVisitor.hpp
@@ -9,32 +9,32 @@ namespace vast::cg
     template< typename derived_t >
     struct unreach_stmt_visitor {
         operation Visit(const clang::Stmt *stmt) {
-            VAST_UNREACHABLE("unsupported stmt: {0}", stmt->getStmtClassName());
+            VAST_FATAL("unsupported stmt: {0}", stmt->getStmtClassName());
         }
     };
 
     template< typename derived_t >
     struct unreach_decl_visitor {
         operation Visit(const clang::Decl *decl) {
-            VAST_UNREACHABLE("unsupported decl: {0}", decl->getDeclKindName());
+            VAST_FATAL("unsupported decl: {0}", decl->getDeclKindName());
         }
     };
 
     template< typename derived_t >
     struct unreach_type_visitor {
         mlir_type Visit(clang::QualType type) {
-            VAST_UNREACHABLE("unsupported type: {0}", type.getAsString());
+            VAST_FATAL("unsupported type: {0}", type.getAsString());
         }
 
         mlir_type Visit(const clang::Type *type) {
-            VAST_UNREACHABLE("unsupported type: {0}", type->getTypeClassName());
+            VAST_FATAL("unsupported type: {0}", type->getTypeClassName());
         }
     };
 
     template< typename derived_t >
     struct unreach_attr_visitor {
         mlir_attr Visit(const clang::Attr *attr) {
-            VAST_UNREACHABLE("unsupported attr: {0}", attr->getSpelling());
+            VAST_FATAL("unsupported attr: {0}", attr->getSpelling());
         }
     };
 
diff --git a/include/vast/Conversion/TypeConverters/HLToStd.hpp b/include/vast/Conversion/TypeConverters/HLToStd.hpp
index ae7034ee25..950b5e1e79 100644
--- a/include/vast/Conversion/TypeConverters/HLToStd.hpp
+++ b/include/vast/Conversion/TypeConverters/HLToStd.hpp
@@ -227,7 +227,7 @@ namespace vast::conv::tc {
                     case 128:
                         return mlir::FloatType::getF128(&mctx);
                     default:
-                        VAST_UNREACHABLE("Cannot lower float bitsize {0}", target_bw);
+                        VAST_FATAL("Cannot lower float bitsize {0}", target_bw);
                 }
             };
         }
diff --git a/include/vast/Dialect/HighLevel/HighLevelTypes.hpp b/include/vast/Dialect/HighLevel/HighLevelTypes.hpp
index 0728e1dfa5..e826e8c2f4 100644
--- a/include/vast/Dialect/HighLevel/HighLevelTypes.hpp
+++ b/include/vast/Dialect/HighLevel/HighLevelTypes.hpp
@@ -166,7 +166,7 @@ namespace vast::hl
             .Case< LongDoubleType >([&] (auto t) { return fty::getF80(ctx);  })
             .Case< Float128Type   >([&] (auto t) { return fty::getF128(ctx); })
             .Default([] (auto t) {
-                VAST_UNREACHABLE("unknown float type: {0}", format_type(t));
+                VAST_FATAL("unknown float type: {0}", format_type(t));
                 return mlir_type();
             });
     }
diff --git a/include/vast/Tower/Tower.hpp b/include/vast/Tower/Tower.hpp
index 6d12a8d31e..ea822a76d8 100644
--- a/include/vast/Tower/Tower.hpp
+++ b/include/vast/Tower/Tower.hpp
@@ -46,7 +46,7 @@ namespace vast::tw {
             auto mod = _modules.back().get();
 
             if (mlir::failed(pm.run(mod))) {
-                VAST_UNREACHABLE("error: some pass in apply() failed");
+                VAST_FATAL("some pass in apply() failed");
             }
 
             handle.mod.walk(loc_rewriter::remove);
diff --git a/include/vast/Util/TypeList.hpp b/include/vast/Util/TypeList.hpp
index 0c0206d6c9..cb5b110c63 100644
--- a/include/vast/Util/TypeList.hpp
+++ b/include/vast/Util/TypeList.hpp
@@ -158,7 +158,7 @@ namespace vast::util {
         constexpr ret dispatch(mlir_type type, fn &&f)
         {
             if constexpr ( list::empty ) {
-                VAST_UNREACHABLE( "missing type to dispatch" );
+                VAST_FATAL( "missing type to dispatch" );
             } else {
                 using head = typename list::head;
 
diff --git a/include/vast/repl/command.hpp b/include/vast/repl/command.hpp
index 30138c7fb8..d336fe0b45 100644
--- a/include/vast/repl/command.hpp
+++ b/include/vast/repl/command.hpp
@@ -60,7 +60,7 @@ namespace vast::repl
             if (token == "ast")     return enum_type::ast;
             if (token == "module")  return enum_type::module;
             if (token == "symbols") return enum_type::symbols;
-            VAST_UNREACHABLE("uknnown show kind: {0}", token.str());
+            VAST_FATAL("uknnown show kind: {0}", token.str());
         }
 
         enum class meta_action { add, get };
@@ -69,7 +69,7 @@ namespace vast::repl
         enum_type from_string(string_ref token) requires(std::is_same_v< enum_type, meta_action >) {
             if (token == "add") return enum_type::add;
             if (token == "get") return enum_type::get;
-            VAST_UNREACHABLE("uknnown action kind: {0}", token.str());
+            VAST_FATAL("uknnown action kind: {0}", token.str());
         }
 
         //
@@ -112,7 +112,7 @@ namespace vast::repl
         template< const char *name, typename params_storage >
         auto get_param(const params_storage &params) {
             if constexpr (std::tuple_size_v< params_storage > == 0) {
-                VAST_UNREACHABLE(("unknown param name " + std::string(name)).c_str());
+                VAST_FATAL(("unknown param name " + std::string(name)).c_str());
             } else {
                 using current = typename std::tuple_element< 0, params_storage >::type;
 
@@ -267,7 +267,7 @@ namespace vast::repl
         }
 
         if constexpr (params_list::empty) {
-            VAST_UNREACHABLE(("no match for param: " + tokens.front()).str().c_str());
+            VAST_FATAL(("no match for param: " + tokens.front()).str().c_str());
         } else {
             using current_param = typename params_list::head;
             using rest          = typename params_list::tail;
@@ -296,7 +296,7 @@ namespace vast::repl
 
         if constexpr (commands::empty) {
             // we did not recursivelly match any of known commands
-            VAST_UNREACHABLE(("no match for command: " + tokens.front()).str().c_str());
+            VAST_FATAL(("no match for command: " + tokens.front()).str().c_str());
         } else {
             using current_command = typename commands::head;
             using rest            = typename commands::tail;
diff --git a/lib/vast/CodeGen/CodeGenDriver.cpp b/lib/vast/CodeGen/CodeGenDriver.cpp
index da77e59b66..077b9764b1 100644
--- a/lib/vast/CodeGen/CodeGenDriver.cpp
+++ b/lib/vast/CodeGen/CodeGenDriver.cpp
@@ -163,7 +163,7 @@ namespace vast::cg
         if (const auto *var = llvm::dyn_cast< clang::VarDecl >(decl))
             return build_global_var_definition(var, !var->hasDefinition());
 
-        VAST_UNREACHABLE("Invalid argument to buildGlobalDefinition()");
+        VAST_FATAL("Invalid argument to buildGlobalDefinition()");
 
     }
 
@@ -312,7 +312,7 @@ namespace vast::cg
             return true;
         }
 
-        VAST_UNREACHABLE("unsupported value decl");
+        VAST_UNIMPLEMENTED_MSG("unsupported value decl");
     }
 
     void codegen_driver::build_default_methods() {
diff --git a/lib/vast/CodeGen/CodeGenStmtVisitor.cpp b/lib/vast/CodeGen/CodeGenStmtVisitor.cpp
index 98233f2e7d..a5e32378bc 100644
--- a/lib/vast/CodeGen/CodeGenStmtVisitor.cpp
+++ b/lib/vast/CodeGen/CodeGenStmtVisitor.cpp
@@ -86,7 +86,7 @@ namespace vast::hl
             case clang::CastKind::CK_MatrixCast: return CastKind::MatrixCast;
         }
 
-        VAST_UNREACHABLE( "unsupported cast kind" );
+        VAST_UNIMPLEMENTED_MSG( "unsupported cast kind" );
     }
 
     IdentKind ident_kind(const clang::PredefinedExpr *expr)
diff --git a/lib/vast/CodeGen/CodeGenTypeVisitor.cpp b/lib/vast/CodeGen/CodeGenTypeVisitor.cpp
index 2b740dda18..0b52eb2e94 100644
--- a/lib/vast/CodeGen/CodeGenTypeVisitor.cpp
+++ b/lib/vast/CodeGen/CodeGenTypeVisitor.cpp
@@ -30,7 +30,7 @@ namespace vast::cg {
             case BuiltinType::UInt128:
                 return hl::IntegerKind::Int128;
             default:
-                VAST_UNREACHABLE("unknown integer kind");
+                VAST_UNIMPLEMENTED_MSG("unknown integer kind");
         }
     }
 
@@ -51,7 +51,7 @@ namespace vast::cg {
             case BuiltinType::Float128:
                 return hl::FloatingKind::Float128;
             default:
-                VAST_UNREACHABLE("unknown floating kind");
+                VAST_UNIMPLEMENTED_MSG("unknown floating kind");
         }
     }
 
diff --git a/lib/vast/Dialect/Core/Linkage.cpp b/lib/vast/Dialect/Core/Linkage.cpp
index b968c2454a..11e15615d3 100644
--- a/lib/vast/Dialect/Core/Linkage.cpp
+++ b/lib/vast/Dialect/Core/Linkage.cpp
@@ -39,7 +39,7 @@ namespace vast::core {
                 return true;
         }
 
-        VAST_UNREACHABLE("No such linkage");
+        VAST_FATAL("No such linkage");
     }
 
     bool is_vardecl_strong_definition(const clang::VarDecl* decl) {
@@ -149,10 +149,8 @@ namespace vast::core {
             case GlobalLinkageKind::PrivateLinkage:
                 return Visibility::Private;
             default:
-                VAST_UNREACHABLE("unsupported linkage kind {0}", stringifyGlobalLinkageKind(linkage));
+                VAST_FATAL("unsupported linkage kind {0}", stringifyGlobalLinkageKind(linkage));
         }
-
-        VAST_UNREACHABLE("missed linkage kind");
     }
 
     GlobalLinkageKind get_declarator_linkage(
diff --git a/lib/vast/Dialect/HighLevel/HighLevelTypes.cpp b/lib/vast/Dialect/HighLevel/HighLevelTypes.cpp
index f24fac26d0..428a077d79 100644
--- a/lib/vast/Dialect/HighLevel/HighLevelTypes.cpp
+++ b/lib/vast/Dialect/HighLevel/HighLevelTypes.cpp
@@ -57,7 +57,7 @@ namespace vast::hl
             }
         }
 
-        VAST_UNREACHABLE("unknown typedef name");
+        VAST_FATAL("unknown typedef name");
     }
 
     auto name_of_record(mlir_type t) -> std::optional< std::string >
@@ -77,7 +77,7 @@ namespace vast::hl
         if (auto ty = type.dyn_cast< TypedefType >())
             return getFunctionType(getTypedefType(ty, mod), mod);
 
-        VAST_UNREACHABLE("unknown type to extract function type");
+        VAST_UNIMPLEMENTED_MSG("unknown type to extract function type");
     }
 
     core::FunctionType getFunctionType(Value callee) {
@@ -102,7 +102,7 @@ namespace vast::hl
             return getFunctionType(value.getType(), mod);
         }
 
-        VAST_UNREACHABLE("unknown callee type");
+        VAST_UNIMPLEMENTED_MSG("unknown callee type");
     }
 
 
diff --git a/lib/vast/Dialect/HighLevel/HighLevelVar.cpp b/lib/vast/Dialect/HighLevel/HighLevelVar.cpp
index f4f801b26e..1516690427 100644
--- a/lib/vast/Dialect/HighLevel/HighLevelVar.cpp
+++ b/lib/vast/Dialect/HighLevel/HighLevelVar.cpp
@@ -38,7 +38,7 @@ namespace vast::hl
             return DeclContextKind::dc_record;
         if (mlir::isa< EnumDeclOp >(st))
             return DeclContextKind::dc_enum;
-        VAST_UNREACHABLE("unknown declaration context");
+        VAST_UNIMPLEMENTED_MSG("unknown declaration context");
     }
 
     bool VarDeclOp::isStaticDataMember() {
@@ -63,7 +63,7 @@ namespace vast::hl
             case StorageClass::sc_private_extern: return false;
         }
 
-        VAST_UNREACHABLE("unknown starage class");
+        VAST_UNIMPLEMENTED_MSG("unknown starage class");
     }
 
     bool VarDeclOp::isStaticLocal() {
diff --git a/lib/vast/Frontend/Action.cpp b/lib/vast/Frontend/Action.cpp
index f369f6f09b..17998798e3 100644
--- a/lib/vast/Frontend/Action.cpp
+++ b/lib/vast/Frontend/Action.cpp
@@ -44,7 +44,7 @@ namespace vast::cc {
                 break;
         }
 
-        VAST_UNREACHABLE("unsupported action type");
+        VAST_FATAL("unsupported action type");
     }
 
     static auto get_output_stream(compiler_instance &ci, string_ref in, output_type act)
diff --git a/lib/vast/Frontend/Consumer.cpp b/lib/vast/Frontend/Consumer.cpp
index ea69b278c9..c676da20c3 100644
--- a/lib/vast/Frontend/Consumer.cpp
+++ b/lib/vast/Frontend/Consumer.cpp
@@ -79,7 +79,7 @@ namespace vast::cc {
 
         if (!vargs.has_option(opt::disable_vast_verifier)) {
             if (!codegen->verify_module()) {
-                VAST_UNREACHABLE("codegen: module verification error before running vast passes");
+                VAST_FATAL("codegen: module verification error before running vast passes");
             }
         }
     }
@@ -213,7 +213,7 @@ namespace vast::cc {
         // diagnostics matched.
         if (verify_diagnostics && src_mgr_handler.verify().failed()) {
             llvm::sys::RunInterruptHandlers();
-            VAST_UNREACHABLE("failed mlir codegen");
+            VAST_FATAL("failed mlir codegen");
         }
 
         // Emit remaining defaulted C++ methods
@@ -233,9 +233,8 @@ namespace vast::cc {
             pipeline_source::ast, output_type::emit_mlir, *mctx, vargs, default_pipelines_config()
         );
 
-        if (mlir::failed(pipeline->run(mod))) {
-            VAST_UNREACHABLE("MLIR pass manager failed when running vast passes");
-        }
+        auto result = pipeline->run(mod);
+        VAST_CHECK(mlir::succeeded(result), "MLIR pass manager failed when running vast passes");
     }
 
     source_language get_source_language(const cc::language_options &opts) {
diff --git a/lib/vast/Frontend/Targets.cpp b/lib/vast/Frontend/Targets.cpp
index afa9fe2185..ac291d0bff 100644
--- a/lib/vast/Frontend/Targets.cpp
+++ b/lib/vast/Frontend/Targets.cpp
@@ -15,7 +15,7 @@ namespace vast::cc {
         if (trg == "cir") {
             return target_dialect::cir;
         }
-        VAST_UNREACHABLE("Unknown option of target dialect: {0}", trg);
+        VAST_FATAL("Unknown option of target dialect: {0}", trg);
     }
 
     std::string to_string(target_dialect target) {
diff --git a/tools/vast-front/compiler_invocation.cpp b/tools/vast-front/compiler_invocation.cpp
index dadd8a2791..346d5f7417 100644
--- a/tools/vast-front/compiler_invocation.cpp
+++ b/tools/vast-front/compiler_invocation.cpp
@@ -51,7 +51,7 @@ namespace vast::cc
             case EmitAssembly: return std::make_unique< vast::cc::emit_assembly_action >(vargs);
             case EmitLLVM: return std::make_unique< vast::cc::emit_llvm_action >(vargs);
             case EmitObj: return std::make_unique< vast::cc::emit_obj_action >(vargs);
-            default: VAST_UNREACHABLE("unsupported frontend action");
+            default: VAST_UNIMPLEMENTED_MSG("unsupported frontend action");
         }
 
         VAST_UNIMPLEMENTED_MSG("not implemented frontend action");
diff --git a/tools/vast-repl/command.cpp b/tools/vast-repl/command.cpp
index 9ec3cbb567..f1f79d73d5 100644
--- a/tools/vast-repl/command.cpp
+++ b/tools/vast-repl/command.cpp
@@ -145,7 +145,7 @@ namespace vast::repl::cmd {
         auto th = state.tower->top();
         for (auto pass : passes) {
             if (mlir::failed(mlir::parsePassPipeline(pass, pm))) {
-                VAST_UNREACHABLE("error: failed to parse pass pipeline");
+                VAST_FATAL("failed to parse pass pipeline");
             }
             th = state.tower->apply(th, pm);
         }
diff --git a/tools/vast-repl/vast-repl.cpp b/tools/vast-repl/vast-repl.cpp
index 765a7676b0..84c1d0c5e3 100644
--- a/tools/vast-repl/vast-repl.cpp
+++ b/tools/vast-repl/vast-repl.cpp
@@ -44,7 +44,7 @@ namespace vast::repl
                 auto params = parse_params< cmd::load::command_params >(args);
                 cli.exec(make_command< cmd::load >(params));
             } else {
-                VAST_UNREACHABLE("unsupported arguments");
+                VAST_FATAL("unsupported arguments");
             }
         }