913bc95964* new syntax for lvalue references: `var b {.byaddr.} = expr`
* on type mismatch, `???(0, 0)` not shown anymore
* * compiler now lowers `var a: {.foo.}: MyType = expr` to foo(a, MyType, expr)
* new pragmas.byaddr defined in pure library code exploiting this lowering
* skip `template foo() {.pragma.}`
19 lines
535 B
Nim
19 lines
535 B
Nim
# see `semLowerLetVarCustomPragma` for compiler support that enables these
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# lowerings
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template byaddr*(lhs, typ, expr) =
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## Allows a syntax for lvalue reference, exact analog to
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## `auto& a = expr;` in C++
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runnableExamples:
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var s = @[10,11,12]
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var a {.byaddr.} = s[0]
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a+=100
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doAssert s == @[110,11,12]
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doAssert a is int
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var b {.byaddr.}: int = s[0]
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doAssert a.addr == b.addr
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when typ is type(nil):
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let tmp = addr(expr)
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else:
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let tmp: ptr typ = addr(expr)
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template lhs: untyped = tmp[]
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