fix(parser): Stage-1 CLI infinite loop - fix ParserExprBox and ParserIdentScanBox (Part 2/3)

**Problem**: Multiple infinite loops in parser expression handling
- ParserIdentScanBox.scan_ident: bb985
- ParserExprBox.parse_factor2: bb1662 (2 loops)
- ParserExprBox.parse_term2: bb1704
- ParserExprBox.parse_sum2
- ParserExprBox.parse_expr2
- ParserExprBox.parse_args2

**Root Cause**: Same `loop(cont == 1)` + nested if-else pattern as Part 1
- MirBuilder generates PHI self-references
- Loop exits jump to wrong blocks

**Solution**: MirBuilder-friendly explicit continue/break pattern
```hako
// BAD:
loop(cont == 1) {
  if condition { action } else { cont = 0 }
}

// GOOD:
loop(true) {
  if condition { action; continue }
  break
}
```

**Files Modified**:
- lang/src/compiler/parser/scan/parser_ident_scan_box.hako: scan_ident explicit continue
- lang/src/compiler/parser/expr/parser_expr_box.hako: 6 loops fixed
  - parse_factor2: 2 method chaining loops (new/identifier)
  - parse_term2: */ operators
  - parse_sum2: +- operators
  - parse_expr2: &&|| operators
  - parse_args2: argument list parsing

**Progress**: 9 total loop patterns fixed (Part 1: 3, Part 2: 6)

**Remaining**: parse_program2 still has infinite loop at different location (bb2816 vs original bb2854) - investigating in Part 3

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

lang/src/compiler/parser/expr/parser_expr_box.hako

@@ -128,9 +128,8 @@ static box ParserExprBox {
       if src.substring(k, k+1) == ")" { k = k + 1 }
       // Build initial New node
       local node = "{\"type\":\"New\",\"class\":\"" + cls + "\",\"args\":" + args_json + "}"
-      // Optional method chain: .method(args...)
+      // Optional method chain: .method(args...) - MirBuilder-friendly
-      local cont_new = 1
+      loop(true) {
-      loop(cont_new == 1) {
         k = ctx.skip_ws(src, k)
         if k >= src.length() { break }
         local tch = src.substring(k, k+1)
@@ -150,9 +149,9 @@ static box ParserExprBox {
           k = ctx.skip_ws(src, k)
           if src.substring(k, k+1) == ")" { k = k + 1 }
           node = "{\"type\":\"Method\",\"recv\":" + node + ",\"method\":\"" + mname + "\",\"args\":" + args_json2 + "}"
-        } else {
+          continue
-          cont_new = 0
         }
+        break
       }
       ctx.gpos_set(k)
       return node
@@ -165,13 +164,13 @@ static box ParserExprBox {
       local name = idp.substring(0, at)
       local k = ctx.to_int(idp.substring(at+1, idp.length()))
       local node = "{\"type\":\"Var\",\"name\":\"" + name + "\"}"
-      local cont2 = 1
 
-      loop(cont2 == 1) {
+      // MirBuilder-friendly: explicit continue/break instead of flag
+      loop(true) {
         k = ctx.skip_ws(src, k)
         local tch = src.substring(k, k+1)
 
-          if tch == "(" {
+        if tch == "(" {
           k = k + 1
           local args_and_pos = ParserExprBox.parse_args2(src, k, ctx)
           local at2 = args_and_pos.lastIndexOf("@")
@@ -180,27 +179,29 @@ static box ParserExprBox {
           k = ctx.skip_ws(src, k)
           if src.substring(k, k+1) == ")" { k = k + 1 }
           node = "{\"type\":\"Call\",\"name\":\"" + name + "\",\"args\":" + args_json + "}"
-        } else {
+          continue
-          if tch == "." {
-            k = k + 1
-            k = ctx.skip_ws(src, k)
-            local midp = ctx.read_ident2(src, k)
-            local at3 = midp.lastIndexOf("@")
-            local mname = midp.substring(0, at3)
-            k = ctx.to_int(midp.substring(at3+1, midp.length()))
-            k = ctx.skip_ws(src, k)
-            if src.substring(k, k+1) == "(" { k = k + 1 }
-            local args2 = ParserExprBox.parse_args2(src, k, ctx)
-            local at4 = args2.lastIndexOf("@")
-            local args_json2 = args2.substring(0, at4)
-            k = ctx.to_int(args2.substring(at4+1, args2.length()))
-            k = ctx.skip_ws(src, k)
-            if src.substring(k, k+1) == ")" { k = k + 1 }
-            node = "{\"type\":\"Method\",\"recv\":" + node + ",\"method\":\"" + mname + "\",\"args\":" + args_json2 + "}"
-          } else {
-            cont2 = 0
-          }
         }
+
+        if tch == "." {
+          k = k + 1
+          k = ctx.skip_ws(src, k)
+          local midp = ctx.read_ident2(src, k)
+          local at3 = midp.lastIndexOf("@")
+          local mname = midp.substring(0, at3)
+          k = ctx.to_int(midp.substring(at3+1, midp.length()))
+          k = ctx.skip_ws(src, k)
+          if src.substring(k, k+1) == "(" { k = k + 1 }
+          local args2 = ParserExprBox.parse_args2(src, k, ctx)
+          local at4 = args2.lastIndexOf("@")
+          local args_json2 = args2.substring(0, at4)
+          k = ctx.to_int(args2.substring(at4+1, args2.length()))
+          k = ctx.skip_ws(src, k)
+          if src.substring(k, k+1) == ")" { k = k + 1 }
+          node = "{\"type\":\"Method\",\"recv\":" + node + ",\"method\":\"" + mname + "\",\"args\":" + args_json2 + "}"
+          continue
+        }
+
+        break
       }
 
       ctx.gpos_set(k)
@@ -226,22 +227,18 @@ static box ParserExprBox {
   parse_term2(src, i, ctx) {
     local lhs = ParserExprBox.parse_unary2(src, i, ctx)
     local j = ctx.gpos_get()
-    local cont = 1
 
-    loop(cont == 1) {
+    // MirBuilder-friendly: explicit continue/break instead of flag
+    loop(true) {
       j = ctx.skip_ws(src, j)
-      if j >= src.length() {
+      if j >= src.length() { break }
-        cont = 0
+
-      } else {
+      local op = src.substring(j, j+1)
-        local op = src.substring(j, j+1)
+      if op != "*" && op != "/" { break }
-        if op != "*" && op != "/" {
+
-          cont = 0
+      local rhs = ParserExprBox.parse_unary2(src, j+1, ctx)
-        } else {
+      j = ctx.gpos_get()
-          local rhs = ParserExprBox.parse_unary2(src, j+1, ctx)
+      lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
-          j = ctx.gpos_get()
-          lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
-        }
-      }
     }
 
     ctx.gpos_set(j)
@@ -251,22 +248,18 @@ static box ParserExprBox {
   parse_sum2(src, i, ctx) {
     local lhs = ParserExprBox.parse_term2(src, i, ctx)
     local j = ctx.gpos_get()
-    local cont = 1
 
-    loop(cont == 1) {
+    // MirBuilder-friendly: explicit continue/break instead of flag
+    loop(true) {
       j = ctx.skip_ws(src, j)
-      if j >= src.length() {
+      if j >= src.length() { break }
-        cont = 0
+
-      } else {
+      local op = src.substring(j, j+1)
-        local op = src.substring(j, j+1)
+      if op != "+" && op != "-" { break }
-        if op != "+" && op != "-" {
+
-          cont = 0
+      local rhs = ParserExprBox.parse_term2(src, j+1, ctx)
-        } else {
+      j = ctx.gpos_get()
-          local rhs = ParserExprBox.parse_term2(src, j+1, ctx)
+      lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
-          j = ctx.gpos_get()
-          lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
-        }
-      }
     }
 
     ctx.gpos_set(j)
@@ -305,18 +298,16 @@ static box ParserExprBox {
   parse_expr2(src, i, ctx) {
     local lhs = ParserExprBox.parse_compare2(src, i, ctx)
     local j = ctx.gpos_get()
-    local cont = 1
 
-    loop(cont == 1) {
+    // MirBuilder-friendly: explicit continue/break instead of flag
+    loop(true) {
       j = ctx.skip_ws(src, j)
       local two = src.substring(j, j+2)
-      if two != "&&" && two != "||" {
+      if two != "&&" && two != "||" { break }
-        cont = 0
+
-      } else {
+      local rhs = ParserExprBox.parse_compare2(src, j+2, ctx)
-        local rhs = ParserExprBox.parse_compare2(src, j+2, ctx)
+      j = ctx.gpos_get()
-        j = ctx.gpos_get()
+      lhs = "{\"type\":\"Logical\",\"op\":\"" + two + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
-        lhs = "{\"type\":\"Logical\",\"op\":\"" + two + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
-      }
     }
 
     j = ctx.skip_ws(src, j)
@@ -354,13 +345,8 @@ static box ParserExprBox {
     j = ctx.gpos_get()
     out = out + e
 
-    // subsequent arguments with guard
+    // subsequent arguments - MirBuilder-friendly
-    local cont_args = 1
+    loop(true) {
-    local guard = 0
-    local max = 100000
-
-    loop(cont_args == 1) {
-      if guard > max { cont_args = 0 } else { guard = guard + 1 }
       local before = j
       j = ctx.skip_ws(src, j)
 
@@ -370,11 +356,10 @@ static box ParserExprBox {
         e = ParserExprBox.parse_expr2(src, j, ctx)
         j = ctx.gpos_get()
         out = out + "," + e
-      } else {
+        continue
-        cont_args = 0
       }
 
-      if j == before { cont_args = 0 }
+      break
     }
 
     out = out + "]"

lang/src/compiler/parser/scan/parser_ident_scan_box.hako

@@ -10,10 +10,14 @@ static box ParserIdentScanBox {
     local ch = src.substring(j, j+1)
     if !(ParserStringUtilsBox.is_alpha(ch) || ch == "_") { return "@" + ParserStringUtilsBox.i2s(i) }
     j = j + 1
+    // MirBuilder-friendly: explicit continue instead of if-else
     loop(j < n) {
       local ch2 = src.substring(j, j+1)
-      if ParserStringUtilsBox.is_alpha(ch2) || ParserStringUtilsBox.is_digit(ch2) || ch2 == "_" { j = j + 1 }
+      if ParserStringUtilsBox.is_alpha(ch2) || ParserStringUtilsBox.is_digit(ch2) || ch2 == "_" {
-      else { break }
+        j = j + 1
+        continue
+      }
+      break
     }
     local s = src.substring(i, j)
     return s + "@" + ParserStringUtilsBox.i2s(j)