adds (discard Expr) to NIFC (nim-lang#119)

.gitignore

@@ -2,4 +2,5 @@ nimcache/
 nimblecache/
 htmldocs/
 *.exe
-nifcache/
+nifcache/
+src/nifc/nifc_grammar.nim

doc/nifc-spec.md

@@ -141,8 +141,9 @@ Stmt ::= Call |
          (case Expr (of BranchRanges StmtList)* (else StmtList)?) |
          (lab SymbolDef) |
          (jmp Symbol) |
-         (scope StmtList)
-         (ret [Empty | Expr]) # return statement
+         (scope StmtList) |
+         (ret [Empty | Expr]) | # return statement
+         (discard Expr)
 
 StmtList ::= (stmts SCOPE Stmt*)
 

src/nifc/codegen.nim

@@ -60,6 +60,7 @@ type
     TypedefKeyword = "typedef "
     IncludeKeyword = "#include "
     LineDirKeyword = "#line "
+    DiscardToken = "(void) "
 
 proc fillTokenTable(tab: var BiTable[Token, string]) =
   for e in EmptyToken..high(PredefinedToken):

src/nifc/genstmts.nim

@@ -201,5 +201,9 @@ proc genStmt(c: var GeneratedCode; t: Tree; n: NodePos) =
       c.add Space
       c.genx t, n.firstSon
     c.add Semicolon
+  of DiscardC:
+    c.add DiscardToken
+    c.genx t, n.firstSon
+    c.add Semicolon
   else:
     error c.m, "expected statement but got: ", t, n

src/nifc/nifc_grammar.nif

@@ -66,7 +66,9 @@
          (lab SYMBOLDEF)
          (jmp SYMBOL)
          (scope StmtList)
-         (ret (OR . Expr))))
+         (ret (OR . Expr))
+         (discard Expr)
+         ))
 
 (RULE :StmtList (SCOPE (stmts (ZERO_OR_MANY Stmt))))
 

src/nifc/nifc_model.nim

@@ -118,6 +118,7 @@ type
     InfC = "inf"
     NegInfC = "neginf"
     NanC = "nan"
+    DiscardC = "discard"
 
 
 const

src/nifc/typenav.nim

@@ -156,5 +156,5 @@ proc getType*(m: var Module; t: Tree; n: NodePos): TypeDesc =
      VoidC, PtrC, ArrayC, FlexarrayC, APtrC, TypeC, CdeclC,
      StdcallC, SafecallC, SyscallC, FastcallC, ThiscallC, NoconvC, MemberC,
      AttrC, InlineC, NoinlineC, VarargsC, WasC, SelectanyC,
-     PragmasC, AlignC, BitsC, VectorC, ImpC, NodeclC, InclC, ScopeC:
+     PragmasC, AlignC, BitsC, VectorC, ImpC, NodeclC, InclC, ScopeC, DiscardC:
     result = errorType()

tests/data/nifc_grammar.nim

@@ -832,6 +832,15 @@ proc matchStmt(c: var Context; it: var Item): bool =
     if kw18:
       or2 = true
       break or3
+    var kw21 = false
+    if isTag(c, it, DiscardT):
+      if not matchExpr(c, it):
+        error(c, it, "Expr expected")
+        break or3
+      kw21 = matchParRi(c, it)
+    if kw21:
+      or2 = true
+      break or3
   if not or2: return false
   when declared(handleStmt):
     handleStmt(c, it, before1)

tests/nifc/issues.nif

@@ -203,6 +203,7 @@
     (call foo.intminmax)
 
     (call foo.inline)
+    (discard (call foo.inline))
     (call foo.noinline)
     (call foo.cdecl)
     (call foo.stdcall)
@@ -212,6 +213,7 @@
     (call foo.member)
 
     (var :x.c . (i +8) (suf +12 "i8"))
+    (discard x.c)
     (var :x.m . (i +16) (suf -12 "i16"))
     (var :x1 . (i +32) (suf +12 "i32"))
     (var :y1 . (u +32) (suf +12 "u32"))