conv needs to be picky about aliases and introduces a temp for addr conv (nim-lang#24818)

ref nim-lang#24817
ref nim-lang#24815
ref status-im/nim-eth#784

```nim
{.emit:"""
void foo(unsigned long long* x)
{
}
""".}

proc foo(x: var culonglong) {.importc: "foo", nodecl.}

proc main(x: var uint64) =
  # var s: culonglong = u # TODO:
  var m = uint64(12)
  # var s = culonglong(m)
  foo(culonglong m)

var u = uint64(12)
main(u)
```
Notes that this code gives incompatible errors in 2.0.0, 2.2.0 and the
devel branch. With this PR, `conv` is kept, but it seems to go back to
nim-lang#24807

(cherry picked from commit f9c8775)

Author: ringabout

compiler/ccgcalls.nim

@@ -307,7 +307,7 @@ proc withTmpIfNeeded(p: BProc, a: TLoc, needsTmp: bool): TLoc =
   else:
     result = a
 
-proc literalsNeedsTmp(p: BProc, a: TLoc): TLoc =
+proc expressionsNeedsTmp(p: BProc, a: TLoc): TLoc =
   result = getTemp(p, a.lode.typ, needsInit=false)
   genAssignment(p, result, a, {})
 
@@ -326,7 +326,7 @@ proc genArg(p: BProc, n: PNode, param: PSym; call: PNode; result: var Rope; need
     (optByRef notin param.options or not p.module.compileToCpp):
     a = initLocExpr(p, n)
     if n.kind in {nkCharLit..nkNilLit}:
-      addAddrLoc(p.config, literalsNeedsTmp(p, a), result)
+      addAddrLoc(p.config, expressionsNeedsTmp(p, a), result)
     else:
       addAddrLoc(p.config, withTmpIfNeeded(p, a, needsTmp), result)
   elif p.module.compileToCpp and param.typ.kind in {tyVar} and

compiler/ccgexprs.nim

@@ -808,6 +808,11 @@ proc cowBracket(p: BProc; n: PNode) =
 proc cow(p: BProc; n: PNode) {.inline.} =
   if n.kind == nkHiddenAddr: cowBracket(p, n[0])
 
+template ignoreConv(e: PNode): bool =
+  let destType = e.typ.skipTypes({tyVar, tyLent, tyGenericInst, tyAlias, tySink})
+  let srcType = e[1].typ.skipTypes({tyVar, tyLent, tyGenericInst, tyAlias, tySink})
+  sameBackendTypePickyAliases(destType, srcType)
+
 proc genAddr(p: BProc, e: PNode, d: var TLoc) =
   # careful  'addr(myptrToArray)' needs to get the ampersand:
   if e[0].typ.skipTypes(abstractInstOwned).kind in {tyRef, tyPtr}:
@@ -820,7 +825,11 @@ proc genAddr(p: BProc, e: PNode, d: var TLoc) =
     d.lode = e
   else:
     var a: TLoc = initLocExpr(p, e[0])
-    putIntoDest(p, d, e, addrLoc(p.config, a), a.storage)
+    if e[0].kind in {nkHiddenStdConv, nkHiddenSubConv, nkConv} and not ignoreConv(e[0]):
+      # addr (conv x) introduces a temp because `conv x` is not a rvalue
+      putIntoDest(p, d, e, addrLoc(p.config, expressionsNeedsTmp(p, a)), a.storage)
+    else:
+      putIntoDest(p, d, e, addrLoc(p.config, a), a.storage)
 
 template inheritLocation(d: var TLoc, a: TLoc) =
   if d.k == locNone: d.storage = a.storage
@@ -2253,8 +2262,7 @@ proc genRangeChck(p: BProc, n: PNode, d: var TLoc) =
       [getTypeDesc(p.module, dest), rdCharLoc(a)], a.storage)
 
 proc genConv(p: BProc, e: PNode, d: var TLoc) =
-  let destType = e.typ.skipTypes({tyVar, tyLent, tyGenericInst, tyAlias, tySink})
-  if sameBackendTypeIgnoreRange(destType, e[1].typ):
+  if ignoreConv(e):
     expr(p, e[1], d)
   else:
     genSomeCast(p, e, d)

compiler/types.nim

@@ -1420,7 +1420,7 @@ proc sameBackendTypeIgnoreRange*(x, y: PType): bool =
 
 proc sameBackendTypePickyAliases*(x, y: PType): bool =
   var c = initSameTypeClosure()
-  c.flags.incl {IgnoreTupleFields, PickyCAliases, PickyBackendAliases}
+  c.flags.incl {IgnoreTupleFields, IgnoreRangeShallow, PickyCAliases, PickyBackendAliases}
   c.cmp = dcEqIgnoreDistinct
   result = sameTypeAux(x, y, c)
 

tests/ccgbugs/taddrconvs.nim

@@ -0,0 +1,27 @@
+discard """
+  targets: "c cpp"
+  matrix: "--mm:refc; --mm:orc"
+"""
+
+{.emit:"""
+void foo(unsigned long long* x)
+{
+}
+""".}
+
+block:
+  proc foo(x: var culonglong) {.importc: "foo", nodecl.}
+
+  proc main(x: var uint64) =
+    foo(culonglong x)
+
+  var u = uint64(12)
+  main(u)
+
+block:
+  proc foo(x: var culonglong) {.importc: "foo", nodecl.}
+
+  proc main() =
+    var m = uint64(12)
+    foo(culonglong(m))
+  main()