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New/better macro pragmas, mark some as experimental (#19406)

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* New/better macro pragmas, make some experimental

fix #15920, close #18212, close #14781, close #6696,
close https://github.com/nim-lang/RFCs/issues/220

Variable macro pragmas have been changed to
only take a unary section node.
They can now also be applied in sections with multiple variables,
as well as `const` sections. They also accept arguments.

Templates now support macro pragmas, mirroring other routine types.

Type and variable macro pragmas have been made experimental.
Symbols without parentheses instatiating nullary macros or templates
has also been documented in the experimental manual.

A check for a redefinition error based on the left hand side of variable
definitions when using variable macro pragmas was disabled.
This nerfs `byaddr` specifically, however this has been documented as
a consequence of the experimental features `byaddr` uses.

Given how simple these changes are I'm worried if I'm missing something.

* accomodate compiler boot

* allow weird pragmas

* add test for #10994

* remove some control flow, try remove some logic
This commit is contained in:
metagn
2022-01-20 22:57:50 +03:00
committed by GitHub
parent 1563cb2f6e
commit 2bd1aa186e
8 changed files with 435 additions and 205 deletions
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64
tests/stdlib/tdecls.nim
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@@ -13,15 +13,18 @@ template fun() =
var b {.byaddr.}: int = s[0]
doAssert a.addr == b.addr
doAssert not compiles(block:
# redeclaration not allowed
var foo = 0
var foo {.byaddr.} = s[0])
when false:
# template specific redeclaration issue
# see https://github.com/nim-lang/Nim/issues/8275
doAssert not compiles(block:
# redeclaration not allowed
var foo = 0
var foo {.byaddr.} = s[0])
doAssert not compiles(block:
# ditto
var foo {.byaddr.} = s[0]
var foo {.byaddr.} = s[0])
doAssert not compiles(block:
# ditto
var foo {.byaddr.} = s[0]
var foo {.byaddr.} = s[0])
block:
var b {.byaddr.} = s[1] # redeclaration ok in sub scope
@@ -44,48 +47,3 @@ fun2()
static: fun2()
when false: # pending bug #13887
static: fun()
## We can define custom pragmas in user code
template byUnsafeAddr(lhs, typ, expr) =
when typ is type(nil):
let tmp = addr(expr)
else:
let tmp: ptr typ = addr(expr)
template lhs: untyped = tmp[]
block:
let s = @["foo", "bar"]
let a {.byUnsafeAddr.} = s[0]
doAssert a == "foo"
doAssert a[0].addr == s[0][0].addr
block: # nkAccQuoted
# shows using a keyword, which requires nkAccQuoted
template `cast`(lhs, typ, expr) =
when typ is type(nil):
let tmp = addr(expr)
else:
let tmp: ptr typ = addr(expr)
template lhs: untyped = tmp[]
block:
let s = @["foo", "bar"]
let a {.`byUnsafeAddr`.} = s[0]
doAssert a == "foo"
doAssert a[0].addr == s[0][0].addr
block:
let s = @["foo", "bar"]
let a {.`cast`.} = s[0]
doAssert a == "foo"
doAssert a[0].addr == s[0][0].addr
block: # bug #15920
template foo(lhs, typ, expr) =
let lhs = expr
proc fun1()=
let a {.foo.} = 1
template fun2()=
let a {.foo.} = 1
fun1() # ok
fun2() # BUG