NIFC: follow scopes for precise typing information (#518)

* NIFC: follow scopes for precise typing information

* NIFC: (addr arr) must produce &arr.a

src/nifc/codegen.nim

@@ -290,7 +290,9 @@ proc genParamPragmas(c: var GeneratedCode; n: var Cursor) =
 proc genParam(c: var GeneratedCode; n: var Cursor) =
   var d = takeParamDecl(n)
   if d.name.kind == SymbolDef:
-    let name = mangle(pool.syms[d.name.symId])
+    let lit = d.name.symId
+    c.m.registerLocal(lit, d.typ)
+    let name = mangle(pool.syms[lit])
     genType c, d.typ, name
     genParamPragmas c, d.pragmas
   else:
@@ -416,6 +418,7 @@ proc genVarDecl(c: var GeneratedCode; n: var Cursor; vk: VarKind; toExtern = fal
   var d = takeVarDecl(n)
   if d.name.kind == SymbolDef:
     let lit = d.name.symId
+    c.m.registerLocal(lit, d.typ)
     let name = mangle(pool.syms[lit])
     let beforeDecl = c.code.len
     if toExtern:
@@ -450,6 +453,7 @@ include genstmts
 
 
 proc genProcDecl(c: var GeneratedCode; n: var Cursor; isExtern: bool) =
+  c.m.openScope()
   let signatureBegin = c.code.len
   var prc = takeProcDecl(n)
 
@@ -546,6 +550,7 @@ proc genProcDecl(c: var GeneratedCode; n: var Cursor; isExtern: bool) =
     c.add CurlyRi
     if isSelectAny in flags:
       genRoutineGuardEnd(c)
+  c.m.closeScope()
 
 proc genInclude(c: var GeneratedCode; n: var Cursor) =
   inc n
@@ -641,6 +646,7 @@ proc generateCode*(s: var State, inp, outp: string; flags: set[GenFlag]) =
   var m = load(inp)
   m.config = s.config
   var c = initGeneratedCode(m, flags)
+  c.m.openScope()
 
   var co = TypeOrder()
   traverseTypes(c.m, co)
@@ -685,3 +691,5 @@ proc generateCode*(s: var State, inp, outp: string; flags: set[GenFlag]) =
     for x in items(c.headerFile):
       write h, c.tokens[x]
     h.close()
+
+  c.m.closeScope()

src/nifc/genexprs.nim

@@ -181,6 +181,18 @@ proc suffixConv(c: var GeneratedCode; value, suffix: Cursor) =
   genx c, value
   c.add ParRi
 
+proc genAddr(c: var GeneratedCode; n: var Cursor) =
+  # If we take the address of an array expression, add the `.a` field access.
+  inc n
+  let arrType = getType(c.m, n)
+  c.add ParLe
+  c.add "&"
+  genx c, n
+  if arrType.typeKind == ArrayT and not c.m.isImportC(arrType):
+    c.add ".a"
+  c.add ParRi
+  skipParRi n
+
 proc genx(c: var GeneratedCode; n: var Cursor) =
   case n.exprKind
   of NoExpr:
@@ -268,7 +280,8 @@ proc genx(c: var GeneratedCode; n: var Cursor) =
     genx c, n
     c.add ParRi
     skipParRi n
-  of AddrC: unOp c, n, "&"
+  of AddrC:
+    genAddr c, n
   of SizeofC:
     c.add "sizeof"
     c.add ParLe

src/nifc/genstmts.nim

@@ -100,10 +100,12 @@ proc genTryCpp(c: var GeneratedCode; n: var Cursor) =
 proc genScope(c: var GeneratedCode; n: var Cursor) =
   c.add CurlyLe
   inc n
+  c.m.openScope()
   while n.kind != ParRi:
     c.genStmt n
   skipParRi n
   c.add CurlyRi
+  c.m.closeScope()
 
 proc genBranchValue(c: var GeneratedCode; n: var Cursor) =
   if n.kind in {IntLit, UIntLit, CharLit, Symbol} or n.exprKind in {TrueC, FalseC}:

src/nifc/nifc_model.nim

@@ -17,6 +17,10 @@ type
     pos*: int
     kind*: NifcSym
 
+  TypeScope* {.acyclic.} = ref object
+    locals*: Table[SymId, Cursor]
+    parent*: TypeScope
+
   Module* = object
     src*: TokenBuf
     types*: seq[int]
@@ -25,12 +29,22 @@ type
     config*: ConfigRef
     mem*: seq[TokenBuf] # for intermediate results such as computed types
     builtinTypes*: Table[string, Cursor]
+    current*: TypeScope
 
 proc bug*(msg: string) {.noreturn.} =
   when defined(debug):
     writeStackTrace()
   quit "BUG: " & msg
 
+proc registerLocal*(c: var Module; s: SymId; typ: Cursor) =
+  c.current.locals[s] = typ
+
+proc openScope*(c: var Module) =
+  c.current = TypeScope(locals: initTable[SymId, Cursor](), parent: c.current)
+
+proc closeScope*(c: var Module) =
+  c.current = c.current.parent
+
 proc skipParRi*(n: var Cursor) =
   # XXX: Give NIFC some better error reporting.
   if n.kind == ParRi:

src/nifc/typenav.nim

@@ -27,6 +27,12 @@ proc getType*(m: var Module; n: Cursor): Cursor =
   of DotToken, Ident, SymbolDef:
     result = createIntegralType(m, "(err)")
   of Symbol:
+    var it {.cursor.} = m.current
+    while it != nil:
+      let res = it.locals.getOrDefault(n.symId)
+      if not cursorIsNil(res):
+        return res
+      it = it.parent
     let d = m.defs.getOrDefault(n.symId)
     if d.pos != 0:
       result = getType(m, m.src.cursorAt(d.pos))