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Expand hoisted default params in sem (#15270)

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* Expand hoisted default params in sem
Introduce ast.newTree{I,IT}
Add test for default params in procs

* Cleanup

* Simplify hoist transformation and expand test
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Clyybber 2020-09-05 22:01:47 +02:00 • committed by GitHub
commit 35ff17410f
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12 changed files with 178 additions and 123 deletions
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47
compiler/transf.nim
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@ -886,43 +886,6 @@ proc commonOptimizations*(g: ModuleGraph; c: PSym, n: PNode): PNode =
else:
result = n
proc hoistParamsUsedInDefault(c: PTransf, call, letSection, defExpr: PNode): PNode =
# This takes care of complicated signatures such as:
# proc foo(a: int, b = a)
# proc bar(a: int, b: int, c = a + b)
#
# The recursion may confuse you. It performs two duties:
#
# 1) extracting all referenced params from default expressions
# into a let section preceding the call
#
# 2) replacing the "references" within the default expression
# with these extracted skLet symbols.
#
# The first duty is carried out directly in the code here, while the second
# duty is activated by returning a non-nil value. The caller is responsible
# for replacing the input to the function with the returned non-nil value.
# (which is the hoisted symbol)
if defExpr.kind == nkSym:
if defExpr.sym.kind == skParam and defExpr.sym.owner == call[0].sym:
let paramPos = defExpr.sym.position + 1
if call[paramPos].kind == nkSym and sfHoisted in call[paramPos].sym.flags:
# Already hoisted, we still need to return it in order to replace the
# placeholder expression in the default value.
return call[paramPos]
let hoistedVarSym = hoistExpr(letSection,
call[paramPos],
getIdent(c.graph.cache, genPrefix),
c.transCon.owner).newSymNode
call[paramPos] = hoistedVarSym
return hoistedVarSym
else:
for i in 0..<defExpr.safeLen:
let hoisted = hoistParamsUsedInDefault(c, call, letSection, defExpr[i])
if hoisted != nil: defExpr[i] = hoisted
proc transform(c: PTransf, n: PNode): PNode =
when false:
var oldDeferAnchor: PNode
@ -989,16 +952,6 @@ proc transform(c: PTransf, n: PNode): PNode =
of nkBreakStmt: result = transformBreak(c, n)
of nkCallKinds:
result = transformCall(c, n)
var call = result
if nfDefaultRefsParam in call.flags:
# We've found a default value that references another param.
# See the notes in `hoistParamsUsedInDefault` for more details.
var hoistedParams = newNodeI(nkLetSection, call.info, 0)
for i in 1..<call.len:
let hoisted = hoistParamsUsedInDefault(c, call, hoistedParams, call[i])
if hoisted != nil: call[i] = hoisted
result = newTree(nkStmtListExpr, hoistedParams, call)
result.typ = call.typ
of nkAddr, nkHiddenAddr:
result = transformAddrDeref(c, n, nkDerefExpr, nkHiddenDeref)
of nkDerefExpr, nkHiddenDeref: