fix: is-operator, try with generic Result, Unwrap exits on panic

Desugar `is` to tag/value equality in bootstrap and selfhost so LIR
no longer drops hIs as false. Resolve monomorphized Result/Option type
names for `?` (_Tag/_Data). Call bux_exit(1) after Unwrap panic messages.
Add is_operator example and document follow-up fixes.

Makefile

@@ -5,7 +5,7 @@ BUILD_DIR := build
 # Project-local nimcache so CI can cache compiles (default is ~/.cache/nim).
 NIMFLAGS ?= --nimcache:nimcache
 
-EXAMPLES := hello fibonacci factorial structs enums methods algebraic_enums generics generics_struct generic_infer generic_infer2 extend_generic pattern_matching strings strings2 map result_option try_operator ownership ownership_checked ownership_release drop_early_return lifetime_elision ctfe ctfe_crc async concurrency os_time process json iter trait_bounds channel sync jwt stdlib_ergonomics tuples func_ptr map_remove array_iter_extra string_extra multi_closure iter_hof closure_control match_let string_interp iter_generic generic_infer_hof struct_tuple_pat match_block nested_patterns match_guards pattern_shadow move_field move_field_partial move_field_remaining move_field_nested move_field_ptr move_cross_fn c_precedence macro_twice macro_repeat macro_nested macro_hygiene macro_unhygienic macro_stmt_pat macro_tt macro_tt_raw macro_type collections_extra generic_enum switch
+EXAMPLES := hello fibonacci factorial structs enums methods algebraic_enums generics generics_struct generic_infer generic_infer2 extend_generic pattern_matching strings strings2 map result_option try_operator ownership ownership_checked ownership_release drop_early_return lifetime_elision ctfe ctfe_crc async concurrency os_time process json iter trait_bounds channel sync jwt stdlib_ergonomics tuples func_ptr map_remove array_iter_extra string_extra multi_closure iter_hof closure_control match_let string_interp iter_generic generic_infer_hof struct_tuple_pat match_block nested_patterns match_guards pattern_shadow move_field move_field_partial move_field_remaining move_field_nested move_field_ptr move_cross_fn c_precedence macro_twice macro_repeat macro_nested macro_hygiene macro_unhygienic macro_stmt_pat macro_tt macro_tt_raw macro_type collections_extra generic_enum switch is_operator
 
 # Platform smoke (macOS CI): full EXAMPLES still runs on Linux.
 EXAMPLES_SMOKE := hello ownership ownership_release strings map move_field move_field_partial move_field_remaining move_field_nested move_field_ptr move_cross_fn c_precedence macro_twice macro_repeat macro_nested macro_hygiene macro_unhygienic macro_stmt_pat macro_tt macro_tt_raw ctfe_crc

bootstrap/c_backend.nim

@@ -346,7 +346,8 @@ proc emitExpr(be: var CBackend, node: HirNode): string =
     return &"(({typ}){operand})"
 
   of hIs:
-    return "true"  # TODO: proper type checking
+    # Should be desugared in hir_lower; keep false if any residual hIs remains
+    return "false"
 
   of hSizeOf:
     let typ = typeToC(be, node.sizeOfType)

bootstrap/hir_lower.nim

@@ -2053,36 +2053,109 @@ proc lowerExpr(ctx: var LowerCtx, expr: Expr): HirNode =
                    typ: typ, loc: loc)
 
   of ekIs:
+    # Desugar `expr is Variant` to a tag comparison so LIR/C backends need no hIs.
+    # Simple enums (no data): subject == Enum_Variant
+    # Algebraic enums: subject.tag == Enum_Variant
     let operand = ctx.lowerExpr(expr.exprIsOperand)
-    var isType = makeUnknown()
+    var variantName = ""
     if expr.exprIsType != nil and expr.exprIsType.kind == tekNamed:
-      isType = makeNamed(expr.exprIsType.typeName)
+      variantName = expr.exprIsType.typeName
-    return HirNode(kind: hIs, isOperand: operand, isType: isType,
+    var enumName = ""
+    var opType = ctx.resolveExprType(expr.exprIsOperand)
+    # Prefer TypeExpr with type args so generic enums monomorphize (Result_int_String)
+    if expr.exprIsOperand != nil and expr.exprIsOperand.kind == ekIdent:
+      if ctx.varTypeExprs.hasKey(expr.exprIsOperand.exprIdent):
+        let te = ctx.varTypeExprs[expr.exprIsOperand.exprIdent]
+        if te != nil:
+          let resolved = ctx.resolveTypeExpr(te)
+          if resolved != nil and resolved.kind == tkNamed and resolved.name.len > 0:
+            opType = resolved
+    if opType != nil and opType.kind == tkNamed:
+      enumName = opType.name
+    if enumName.len > 0 and variantName.len > 0:
+      var baseName = enumName
+      if ctx.structInstMap.hasKey(enumName):
+        baseName = ctx.structInstMap[enumName].baseName
+      var hasData = ctx.enumHasDataVariants(baseName)
+      if not hasData:
+        hasData = ctx.enumHasDataVariants(enumName)
+      # Monomorphized data enums always have tag+data layout
+      if not hasData and ctx.structInstMap.hasKey(enumName):
+        hasData = true
+      let tagName = enumName & "_" & variantName
+      if hasData:
+        let tagField = HirNode(kind: hFieldPtr, fieldPtrBase: operand, fieldName: "tag",
+                               typ: makePointer(makeNamed(enumName & "_Tag")), loc: loc)
+        let tagLoad = HirNode(kind: hLoad, loadPtr: tagField,
+                               typ: makeNamed(enumName & "_Tag"), loc: loc)
+        let tagConst = hirVar(tagName, makeNamed(enumName & "_Tag"), loc)
+        return hirBinary(tkEq, tagLoad, tagConst, makeBool(), loc)
+      else:
+        let tagConst = hirVar(tagName, makeNamed(enumName), loc)
+        return hirBinary(tkEq, operand, tagConst, makeBool(), loc)
+    # Non-enum / unresolved: false
+    return HirNode(kind: hLit,
+                   litToken: Token(kind: tkBoolLiteral, text: "false", loc: loc),
                    typ: makeBool(), loc: loc)
 
   of ekTry:
     let operand = ctx.lowerExpr(expr.exprTryOperand)
-    let operandType = ctx.resolveExprType(expr.exprTryOperand)
+    var operandType = ctx.resolveExprType(expr.exprTryOperand)
 
     var typeName = ""
     var errTag = ""
     var okField = ""
-    if operandType.kind == tkNamed:
+    if operandType != nil and operandType.kind == tkNamed:
       typeName = operandType.name
-      case typeName
+    else:
-      of "Result":
+      typeName = "Result"
-        errTag = "Result_Err"
+
-        okField = "Ok_0"
+    # Upgrade bare generic enum name to concrete monomorphization.
-      of "Option":
+    # Sema stores Result/Option without mangled type-args; try needs Result_int_String_Tag.
-        errTag = "Option_None"
+    if ctx.genericEnums.hasKey(typeName):
+      # Prefer resolving call/ident TypeExpr with type args
+      if expr.exprTryOperand != nil:
+        if expr.exprTryOperand.kind == ekIdent and ctx.varTypeExprs.hasKey(expr.exprTryOperand.exprIdent):
+          let te = ctx.varTypeExprs[expr.exprTryOperand.exprIdent]
+          if te != nil:
+            let resolved = ctx.resolveTypeExpr(te)
+            if resolved != nil and resolved.kind == tkNamed and resolved.name.startsWith(typeName & "_"):
+              typeName = resolved.name
+        elif expr.exprTryOperand.kind == ekCall and expr.exprTryOperand.exprCallCallee != nil and
+             expr.exprTryOperand.exprCallCallee.kind == ekIdent:
+          let calSym = ctx.globalScope.lookup(expr.exprTryOperand.exprCallCallee.exprIdent)
+          if calSym != nil and calSym.decl != nil and calSym.decl.kind == dkFunc and
+             calSym.decl.declFuncReturnType != nil:
+            let resolved = ctx.resolveTypeExpr(calSym.decl.declFuncReturnType)
+            if resolved != nil and resolved.kind == tkNamed and
+               (resolved.name == typeName or resolved.name.startsWith(typeName & "_")):
+              typeName = resolved.name
+      # Enclosing function return type (must match for `?` propagation)
+      let stillBare = operandType == nil or operandType.kind != tkNamed or
+                      typeName == operandType.name
+      if stillBare and ctx.currentFuncRetType != nil and
+         ctx.currentFuncRetType.kind == tkNamed:
+        let rn = ctx.currentFuncRetType.name
+        if rn.startsWith(typeName & "_"):
+          typeName = rn
+      operandType = makeNamed(typeName)
+
+    # Err tag / Ok field from base or concrete name
+    let baseForTags =
+      if ctx.structInstMap.hasKey(typeName): ctx.structInstMap[typeName].baseName
+      elif ctx.genericEnums.hasKey(typeName): typeName
+      else: typeName
+    if baseForTags == "Option" or typeName.startsWith("Option_"):
+      errTag = typeName & "_None"
+      if typeName == "Option": errTag = "Option_None"
       okField = "Some_0"
+    elif baseForTags == "Result" or typeName.startsWith("Result_"):
+      errTag = typeName & "_Err"
+      if typeName == "Result": errTag = "Result_Err"
+      okField = "Ok_0"
     else:
       errTag = typeName & "_Err"
       okField = "Ok_0"
-    else:
-      errTag = "Result_Err"
-      okField = "Ok_0"
-      typeName = "Result"
 
     let tmpName = ctx.freshTryVar()
     let tmpAlloca = hirAlloca(tmpName, operandType, loc)
@@ -3084,8 +3157,10 @@ proc lowerModule*(module: Module, sema: Sema): HirModule =
             if en.name.startsWith(enumName & "_"):
               return en.name & "_" & rest
 
-  # Also substitute type names in hAlloca and hStructInit from extraEnums
+  # Substitute type names in Type fields (Result → Result_int_String,
+  # Result_Tag → Result_int_String_Tag, Result_Data → Result_int_String_Data).
   proc substEnumType(typ: var Type, ctx: LowerCtx) =
+    if typ == nil: return
     if typ.kind == tkNamed:
       for enumName, _ in ctx.genericEnums:
         if typ.name == enumName:
@@ -3093,15 +3168,32 @@ proc lowerModule*(module: Module, sema: Sema): HirModule =
             if en.name.startsWith(enumName & "_"):
               typ = makeNamed(en.name)
               return
+        # Suffix forms used by try/field lowering
+        let tagSuffix = enumName & "_Tag"
+        let dataSuffix = enumName & "_Data"
+        if typ.name == tagSuffix or typ.name == dataSuffix:
+          let rest = typ.name[enumName.len + 1 .. ^1]  # "Tag" or "Data"
+          for en in ctx.extraEnums:
+            if en.name.startsWith(enumName & "_"):
+              typ = makeNamed(en.name & "_" & rest)
+              return
+    elif typ.kind in {tkPointer, tkRef, tkMutRef, tkSlice} and typ.inner.len > 0:
+      var inner = typ.inner[0]
+      substEnumType(inner, ctx)
+      typ.inner[0] = inner
 
   proc mangleHirNode(n: HirNode, ctx: LowerCtx) =
     if n == nil: return
+    # Mangle type annotation on every node (temps for .tag/.data loads)
+    if n.typ != nil:
+      substEnumType(n.typ, ctx)
     case n.kind
     of hVar:       n.varName = substEnumName(n.varName, ctx)
     of hStructInit: n.structInitName = substEnumName(n.structInitName, ctx)
     of hFieldAccess: n.fieldAccessName = substEnumName(n.fieldAccessName, ctx)
     of hArrowField: n.arrowFieldName = substEnumName(n.arrowFieldName, ctx)
     of hAlloca:     substEnumType(n.allocaType, ctx)
+    of hCast:       substEnumType(n.castType, ctx)
     else: discard
     # Walk children by variant
     case n.kind

docs/IMPROVEMENTS.md

@@ -34,6 +34,15 @@
 
 ---
 
+## Follow-up fixes (post DeepSeek session)
+
+| # | Бъг | Фикс |
+|---|-----|------|
+| F.1 | `is` → LIR `unhandled hIs` / always false | Desugar to `==` / `.tag ==` in bootstrap + selfhost |
+| F.2 | `?` + `Result<T,E>` → `Result_Tag` C error | Concrete monomorphized typeName + `_Tag`/`_Data` mangling |
+| F.3 | `Unwrap` panic continues with garbage | `bux_exit(1)` after panic in Result/Option |
+| F.4 | Regression example | `examples/is_operator.bux` |
+
 ## Резултат
 
 - **Всички тестове: 0 FAIL, 0 error**
@@ -44,6 +53,8 @@
   - Data field достъп (`p.data.First_0` като l-value и r-value)
   - Множество конкретни инстанции в един файл
   - `Result<T,E>` и `Option<T>` в stdlib
+  - `is` operator (simple + algebraic enums)
+  - `?` try operator with monomorphized `Result<T,E>`
 
 ## Пример който работи
 

examples/is_operator.bux

@@ -0,0 +1,40 @@
+// is_operator.bux — `expr is Variant` for simple and algebraic enums
+import Std::Io::{PrintLine, PrintInt};
+
+enum Color {
+    Red,
+    Green,
+    Blue,
+}
+
+enum Box {
+    Val(int),
+    Empty,
+}
+
+func Main() -> int {
+    let c: Color = Color { tag: Color_Red };
+    if c is Red {
+        PrintLine("color-red");
+    }
+    if c is Blue {
+        PrintLine("color-blue-unexpected");
+    } else {
+        PrintLine("color-not-blue");
+    }
+
+    let b: Box = Box { tag: Box_Val };
+    b.data.Val_0 = 42;
+    if b is Val {
+        Print("box-val=");
+        PrintInt(b.data.Val_0 as int64);
+        PrintLine("");
+    }
+    if b is Empty {
+        PrintLine("box-empty-unexpected");
+    } else {
+        PrintLine("box-not-empty");
+    }
+
+    return 0;
+}

lib/Option.bux

@@ -29,6 +29,7 @@ module Std::Option {
     func Option_Unwrap<T>(o: Option<T>) -> T {
         if o.tag != Option_Some {
             PrintLine("panic: unwrap on None");
+            bux_exit(1);
         }
         return o.data.Some_0;
     }

lib/Result.bux

@@ -31,6 +31,7 @@ module Std::Result {
     func Result_Unwrap<T, E>(r: Result<T, E>) -> T {
         if r.tag != Result_Ok {
             PrintLine("panic: unwrap on Err");
+            bux_exit(1);
         }
         return r.data.Ok_0;
     }
@@ -53,6 +54,7 @@ module Std::Result {
     func Result_UnwrapErr<T, E>(r: Result<T, E>) -> E {
         if r.tag != Result_Err {
             PrintLine("panic: unwrap_err on Ok");
+            bux_exit(1);
         }
         return r.data.Err_0;
     }

src/c_backend.bux

@@ -1498,10 +1498,8 @@ module CBackend {
             return;
         }
 
-        // Is (type test): check if the tag of an enum matches a variant
+        // Is (type test): should be desugared to hBinary in HIR lowering
         if kind == hIs {
-            // Should have been lowered to hBinary in HIR lowering
-            // Fallback: always emit false
             StringBuilder_Append(&cbe.sb, "0");
             return;
         }

src/hir_lower.bux

@@ -803,7 +803,7 @@ module HirLower {
     func Lcx_EnumHasData(ctx: *LowerCtx, enumName: String) -> bool {
         if String_Eq(enumName, "") { return false; }
         let sym: Symbol = Scope_Lookup(ctx.scope, enumName);
-        if sym.decl == null as *Decl || sym.decl.kind != dkEnum { return false; }
+        if sym.decl != null as *Decl && sym.decl.kind == dkEnum {
             if sym.decl.variantCount > 0 && sym.decl.variant0.fieldCount > 0 { return true; }
             if sym.decl.variantCount > 1 && sym.decl.variant1.fieldCount > 0 { return true; }
             if sym.decl.variantCount > 2 && sym.decl.variant2.fieldCount > 0 { return true; }
@@ -815,6 +815,40 @@ module HirLower {
             if sym.decl.variantCount > 8 && sym.decl.variant8.fieldCount > 0 { return true; }
             return false;
         }
+        // Monomorphized instance (Result_int_String) — check HIR enums
+        if ctx.hm != null as *HirModule {
+            var i: int = 0;
+            while i < ctx.hm.enumCount {
+                if String_Eq(ctx.hm.enums[i].name, enumName) {
+                    var vi: int = 0;
+                    while vi < ctx.hm.enums[i].variantCount {
+                        if ctx.hm.enums[i].variants[vi].fieldCount > 0 { return true; }
+                        vi = vi + 1;
+                    }
+                    return false;
+                }
+                i = i + 1;
+            }
+        }
+        // Bare prefix of monomorphized generic enum: Result_int_String → Result
+        var gi: int = 0;
+        while gi < ctx.genStructCount {
+            if ctx.genStructs[gi].kind == dkEnum {
+                let base: String = ctx.genStructs[gi].strValue;
+                let prefix: String = String_Concat(base, "_");
+                let prefLen: int = String_Len(prefix) as int;
+                let nameLen: int = String_Len(enumName) as int;
+                if nameLen > prefLen {
+                    let p: String = bux_str_slice(enumName, 0, prefLen as uint);
+                    if String_Eq(p, prefix) {
+                        return Lcx_EnumHasData(ctx, base);
+                    }
+                }
+            }
+            gi = gi + 1;
+        }
+        return false;
+    }
 
     func Lcx_MakeLitHir(litKind: int, litText: String, line: uint32, col: uint32) -> *HirNode {
         let n: *HirNode = bux_alloc(sizeof(HirNode)) as *HirNode;
@@ -2509,39 +2543,52 @@ module HirLower {
             return n;
         }
 
-        // Is (type test): expr is Type — lowered to tag check for enums
+        // Is (type test): expr is Variant — desugar to tag / value equality
+        // Simple enums: subject == Enum_Variant
+        // Algebraic enums: subject.tag == Enum_Variant
         if kind == ekIs {
             let operand: *HirNode = Lcx_LowerExpr(ctx, expr.child1);
-            if expr.refType != null as *TypeExpr {
+            var variantName: String = "";
-                let isType: String = "";
+            if expr.refType != null as *TypeExpr && !String_Eq(expr.refType.typeName, "") {
-                if !String_Eq(expr.refType.typeName, "") {
+                variantName = expr.refType.typeName;
-                    isType = expr.refType.typeName;
             }
-                if !String_Eq(isType, "") {
+            var enumName: String = "";
-                    // Check if operand is an enum type — resolve from HIR type info
+            // Resolve operand type from scope (variable / param), not enum decl name
-                    let enumName: String = "";
             if expr.child1 != null as *Expr && expr.child1.kind == ekIdent {
                 let sym: Symbol = Scope_Lookup(ctx.scope, expr.child1.strValue);
-                        if sym.decl != null as *Decl && sym.decl.kind == dkEnum {
+                if !String_Eq(sym.typeName, "") {
-                            enumName = expr.child1.strValue;
+                    enumName = sym.typeName;
+                } else if sym.refType != null as *TypeExpr {
+                    let te: *TypeExpr = Lcx_SubstituteType(ctx, sym.refType);
+                    if te != null as *TypeExpr && !String_Eq(te.typeName, "") {
+                        enumName = te.typeName;
                     }
                 }
-                    if !String_Eq(enumName, "") {
+            }
-                        let tagName: String = String_Concat(String_Concat(enumName, "_"), isType);
+            // Fallback: type annotation on the is-expression operand
-                        // tagPtr = operand.tag
+            if String_Eq(enumName, "") && expr.child1 != null as *Expr &&
+               expr.child1.refType != null as *TypeExpr {
+                let te: *TypeExpr = Lcx_SubstituteType(ctx, expr.child1.refType);
+                if te != null as *TypeExpr && !String_Eq(te.typeName, "") {
+                    enumName = te.typeName;
+                }
+            }
+            if !String_Eq(enumName, "") && !String_Eq(variantName, "") {
+                let hasData: bool = Lcx_EnumHasData(ctx, enumName);
+                let tagName: String = String_Concat(String_Concat(enumName, "_"), variantName);
+                if hasData {
+                    // subject.tag == Enum_Variant
                     let tagPtr: *HirNode = bux_alloc(sizeof(HirNode)) as *HirNode;
                     tagPtr.kind = hFieldPtr;
                     tagPtr.line = expr.line;
                     tagPtr.column = expr.column;
                     tagPtr.strValue = "tag";
                     tagPtr.child1 = operand;
-                        // tagLoad = *tagPtr
                     let tagLoad: *HirNode = bux_alloc(sizeof(HirNode)) as *HirNode;
                     tagLoad.kind = hLoad;
                     tagLoad.line = expr.line;
                     tagLoad.column = expr.column;
                     tagLoad.child1 = tagPtr;
-                        // tagConst = Enum_Target
                     let tagConst: *HirNode = bux_alloc(sizeof(HirNode)) as *HirNode;
                     tagConst.kind = hVar;
                     tagConst.line = expr.line;
@@ -2550,11 +2597,19 @@ module HirLower {
                     let result: *HirNode = Lcx_MakeBinHir(tkEq, tagLoad, tagConst, expr.line, expr.column);
                     result.sourceFile = ctx.currentSourceFile;
                     return result;
+                } else {
+                    // Simple enum: subject == Enum_Variant
+                    let tagConst: *HirNode = bux_alloc(sizeof(HirNode)) as *HirNode;
+                    tagConst.kind = hVar;
+                    tagConst.line = expr.line;
+                    tagConst.column = expr.column;
+                    tagConst.strValue = tagName;
+                    let result: *HirNode = Lcx_MakeBinHir(tkEq, operand, tagConst, expr.line, expr.column);
+                    result.sourceFile = ctx.currentSourceFile;
+                    return result;
                 }
             }
-            }
+            // Non-enum / unresolved → false
-            // Fallback: emit a compile-time error diagnostic via HIR comment
-            // For non-enum types, is always returns false at runtime
             let result: *HirNode = bux_alloc(sizeof(HirNode)) as *HirNode;
             result.kind = hLit;
             result.line = expr.line;
@@ -2668,19 +2723,43 @@ module HirLower {
             if stmt.child1 != null as *Expr && stmt.child1.kind == ekTry {
                 let tryExpr: *Expr = stmt.child1;
                 let operandExpr: *Expr = tryExpr.child1;
-                let operandTypeExpr: *TypeExpr = operandExpr.refType;
+                let operandTypeExpr: *TypeExpr = if operandExpr != null as *Expr { operandExpr.refType } else { null as *TypeExpr };
                 var typeName: String = "Result";
                 var errTag: String = "Result_Err";
                 var okField: String = "Ok_0";
                 if operandTypeExpr != null as *TypeExpr && operandTypeExpr.kind == tekNamed {
+                    // Substitute/mangle generic enum type args (Result<int,String> → Result_int_String)
+                    let subTe: *TypeExpr = Lcx_SubstituteType(ctx, operandTypeExpr);
+                    if subTe != null as *TypeExpr && !String_Eq(subTe.typeName, "") {
+                        typeName = subTe.typeName;
+                    } else {
                         typeName = operandTypeExpr.typeName;
+                    }
+                }
+                // Detect Option vs Result (bare or monomorphized)
+                var isOption: bool = String_Eq(typeName, "Option");
+                if !isOption {
+                    let optPrefix: String = "Option_";
+                    let tnLen: int = String_Len(typeName) as int;
+                    let prefLen: int = String_Len(optPrefix) as int;
+                    if tnLen > prefLen {
+                        let p: String = bux_str_slice(typeName, 0, prefLen as uint);
+                        if String_Eq(p, optPrefix) { isOption = true; }
+                    }
+                }
+                if isOption {
                     if String_Eq(typeName, "Option") {
                         errTag = "Option_None";
-                        okField = "Some_0";
+                    } else {
-                    } else if !String_Eq(typeName, "Result") {
+                        errTag = String_Concat(typeName, "_None");
-                        errTag = String_Concat(String_Concat(typeName, "_"), "Err");
-                        okField = "Ok_0";
                     }
+                    okField = "Some_0";
+                } else if String_Eq(typeName, "Result") {
+                    errTag = "Result_Err";
+                    okField = "Ok_0";
+                } else {
+                    errTag = String_Concat(typeName, "_Err");
+                    okField = "Ok_0";
                 }
                 let tmpName: String = String_Concat("__try_tmp_", String_FromInt(ctx.tryCounter as int64));
                 ctx.tryCounter = ctx.tryCounter + 1;