feat(lang): L4 type checker between parse and emit

selfhost/check/ walks every function, the entry, tests, globals' initializers and
@On listeners with real scopes, and refuses mixed number kinds, text and numbers,
two record types, mismatched slices and fn types, wrong argument counts, wrong
returns and wrong push elements - every mix-up at once, each at its line.
LUDIC_CHECK_REPORT=1 lists them by category. pointer stays untyped (L7's).

What it found is fixed: render3d's HDR scan calling the float-bits extern f_lt
with floats; ludic.shooter's right-stick aim overflowing past half a push;
prof.ludic storing longs in []int; extern arguments now coerced to their
parameters. Text-returning runtime functions say string; Assets.ready says bool.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

selfhost/backend/emit_call.ludic

@@ -1377,13 +1377,24 @@ function emit_call(e: Node) -> Val {
   let ext = find_extern(name)
   if (ext != null) {
     reorder_named(e, param_labels(ext))
+    # each argument is coerced to its parameter, as a function's are: passed as its own
+    # type, a float given to an int parameter arrived in a float register the callee
+    # never reads, and the callee compared whatever the integer register held
+    let eptys = param_types(ext)
     let eargs = new []pointer
     let eatys = new []pointer
     var ei = 0
-    while ei < len(e.kids) { let v = emit_expr(e.kids[ei]);  push(eargs, v.code);  push(eatys, v.ty);  ei += 1 }
+    while ei < len(e.kids) {
+      let v = emit_expr(e.kids[ei])
+      var pty = v.ty
+      if ei < len(eptys) { pty = eptys[ei] }
+      push(eargs, coerce_code(v, pty))
+      push(eatys, pty)
+      ei += 1
+    }
     let erl = llty(ext.ty)
     emit("  ")
-    var erreg = "0"
+    var erreg: pointer = "0"
     if not (erl == "void") { erreg = nreg();  emit(erreg);  emit(" = ") }
     emit("call ");  emit(erl);  emit(" @");  emit(ext.a.s);  emit("(")
     ei = 0
@@ -1425,7 +1436,7 @@ function emit_call(e: Node) -> Val {
   }
   let rl = llty(fn2.ty)
   emit("  ")
-  var rreg = "0"
+  var rreg: pointer = "0"
   if not (rl == "void") { rreg = nreg();  emit(rreg);  emit(" = ") }
   emit("call ");  emit(rl);  emit(" @fn_");  emit(cname);  emit("(")
   i = 0

selfhost/backend/emit_float.ludic

@@ -168,7 +168,7 @@ function lit_as_fixed(v: Val) -> Val {
 function emit_fp_bin(op: pointer, a: Val, b: Val) -> Val {
   if (a.ty == "fixed") and not (fixed_lit_code(b) == "") { return emit_bin_vals(op, a, lit_as_fixed(b), false) }
   if (b.ty == "fixed") and not (fixed_lit_code(a) == "") { return emit_bin_vals(op, lit_as_fixed(a), b, false) }
-  var t = "float"
+  var t: pointer = "float"
   if is_fp(a.ty) and is_fp(b.ty) { t = fp_result(a.ty, b.ty) }
   else { if is_fp(a.ty) { t = a.ty } else { t = b.ty } }
   let ac = to_fp(a, t, `the left side of {op}`)
@@ -336,7 +336,7 @@ function fp_pick(meth: pointer, t: pointer, x: pointer, y: pointer) -> pointer {
 # the float type a Math call works in, given its already-evaluated first
 # argument and the static types of the rest; "" when it is not a float call
 function fp_math_type(first: Val, e: Node) -> pointer {
-  var t = ""
+  var t: pointer = ""
   if is_fp(first.ty) { t = first.ty }
   var i = 1
   while i < len(e.kids) {

selfhost/backend/emit_fnval.ludic

@@ -79,7 +79,7 @@ function emit_indirect_call(fv: Val, e: Node) -> Val {
   }
   let rl = llty(ret)
   emit("  ")
-  var rreg = "0"
+  var rreg: pointer = "0"
   if not (rl == "void") {
     rreg = nreg()
     emit(rreg)

selfhost/backend/emit_stmt.ludic

@@ -28,8 +28,8 @@ function compound_op(tok: pointer) -> pointer {
 function emit_assign(st: Node) -> void {
   # resolve the target's address and type
   let t = st.a
-  var addr = "0"
-  var ty = "int"
+  var addr: pointer = "0"
+  var ty: pointer = "int"
   if t.kind == E_ID {
     let li = loc_find(t.s)
     if li >= 0 {
@@ -209,7 +209,7 @@ function emit_match_tagged(st: Node, sv: Val, en: Node) -> void {
     let arm = st.kids[i]
     if arm_is_default(arm) { deflt = arm }
     else {
-      var acc = "0"
+      var acc: pointer = "0"
       var first = true
       var bindPat: Node = null
       var p = 0
@@ -262,7 +262,7 @@ function emit_match(st: Node) -> void {
     let arm = st.kids[i]
     if arm_is_default(arm) { deflt = arm }
     else {
-      var acc = "0"
+      var acc: pointer = "0"
       var first = true
       var p = 0
       while p < len(arm.kids) {
@@ -303,7 +303,7 @@ function emit_emit(st: Node) -> Val {
     var j = 0
     while j < len(st.a.kids) { if (st.a.kids[j].s == fd.s) { av = st.a.kids[j].a };  j += 1 }
     let lt = llty(fd.ty)
-    var code = "0"
+    var code: pointer = "0"
     if (lt == "ptr") { code = "null" }
     if (av != null) { let v = emit_expr(av);  code = v.code }
     else { if (fd.a != null) { let dv = emit_expr(fd.a);  code = dv.code } }   # declared default

selfhost/backend/game/emit_machine.ludic

@@ -30,7 +30,7 @@ function machine_state_value(m: Node, state: Node) -> pointer {
 
 function emit_machine(st: Node) -> void {
   let gv = machine_var(st.a)
-  var s = ""
+  var s: pointer = ""
   if (gv != null) { s = emit_bind(`load i32, ptr @g_{st.a.s}`) }
   else {
     let regv = emit_expr(st.a)

selfhost/backend/game/emit_query.ludic

@@ -38,7 +38,7 @@ function emit_query(st: Node) -> void {
   while t < len(terms.kids) {
     let tm = terms.kids[t]
     let ak = find_arch_id(tm.s)
-    var ok = "0"
+    var ok: pointer = "0"
     if ak > 0 {
       let kp = nreg();  emit("  ");  emit(kp);  emit(" = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_kind, i32 0, i32 ");  emit(i1);  emit("\n")
       let kv = emit_bind(`load i32, ptr {kp}`)