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Properly wrap discarded statements (#10322)

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Failing to do so lead the codegen to emit invalid code sometimes,
especially when C++ references were involved.

Fixes #10241
This commit is contained in:
LemonBoy 2019-01-17 07:55:29 +01:00 • committed by Andreas Rumpf
commit 15584879b9
3 changed files with 35 additions and 12 deletions
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24
compiler/semstmts.nim
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@ -130,13 +130,13 @@ proc fixNilType(c: PContext; n: PNode) =
for it in n: fixNilType(c, it)
n.typ = nil
proc discardCheck(c: PContext, result: PNode, flags: TExprFlags) =
proc discardCheck(c: PContext, expr: PNode, flags: TExprFlags): PNode =
result = expr
if c.matchedConcept != nil or efInTypeof in flags: return
if result.typ != nil and result.typ.kind notin {tyStmt, tyVoid}:
if implicitlyDiscardable(result):
var n = newNodeI(nkDiscardStmt, result.info, 1)
n[0] = result
result = newNode(nkDiscardStmt, result.info, @[result])
elif result.typ.kind != tyError and c.config.cmd != cmdInteractive:
var n = result
while n.kind in skipForDiscardable: n = n.lastSon
@ -168,7 +168,8 @@ proc semIf(c: PContext, n: PNode; flags: TExprFlags): PNode =
else: illFormedAst(it, c.config)
if isEmptyType(typ) or typ.kind in {tyNil, tyExpr} or
(not hasElse and efInTypeof notin flags):
for it in n: discardCheck(c, it.lastSon, flags)
for it in n:
it.sons[^1] = discardCheck(c, it.sons[^1], flags)
result.kind = nkIfStmt
# propagate any enforced VoidContext:
if typ == c.enforceVoidContext: result.typ = c.enforceVoidContext
@ -266,12 +267,14 @@ proc semTry(c: PContext, n: PNode; flags: TExprFlags): PNode =
dec c.p.inTryStmt
if isEmptyType(typ) or typ.kind in {tyNil, tyExpr}:
discardCheck(c, n.sons[0], flags)
for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon, flags)
n.sons[0] = discardCheck(c, n.sons[0], flags)
for i in 1..n.len-1:
n.sons[i].sons[^1] = discardCheck(c, n.sons[i].sons[^1], flags)
if typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
else:
if n.lastSon.kind == nkFinally: discardCheck(c, n.lastSon.lastSon, flags)
if n.lastSon.kind == nkFinally:
n.sons[^1].sons[^1] = discardCheck(c, n.sons[^1].sons[^1], flags)
n.sons[0] = fitNode(c, typ, n.sons[0], n.sons[0].info)
for i in 1..last:
var it = n.sons[i]
@ -679,7 +682,7 @@ proc semForVars(c: PContext, n: PNode; flags: TExprFlags): PNode =
openScope(c)
n.sons[length-1] = semExprBranch(c, n.sons[length-1], flags)
if efInTypeof notin flags:
discardCheck(c, n.sons[length-1], flags)
n.sons[^1] = discardCheck(c, n.sons[^1], flags)
closeScope(c)
dec(c.p.nestedLoopCounter)
@ -866,7 +869,8 @@ proc semCase(c: PContext, n: PNode; flags: TExprFlags): PNode =
closeScope(c)
if isEmptyType(typ) or typ.kind in {tyNil, tyExpr} or
(not hasElse and efInTypeof notin flags):
for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon, flags)
for i in 1..n.len-1:
n.sons[i].sons[^1] = discardCheck(c, n.sons[i].sons[^1], flags)
# propagate any enforced VoidContext:
if typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
@ -2029,7 +2033,7 @@ proc semStmtList(c: PContext, n: PNode, flags: TExprFlags): PNode =
n.typ = n.sons[i].typ
if not isEmptyType(n.typ): n.kind = nkStmtListExpr
elif i != last or voidContext:
discardCheck(c, n.sons[i], flags)
n.sons[i] = discardCheck(c, n.sons[i], flags)
else:
n.typ = n.sons[i].typ
if not isEmptyType(n.typ): n.kind = nkStmtListExpr