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author | Kartik Agaram <vc@akkartik.com> | 2020-06-15 17:00:26 -0700 |
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committer | Kartik Agaram <vc@akkartik.com> | 2020-06-15 17:13:04 -0700 |
commit | d292196ff5ab9f103364e05c42a1edc03dc1b5ab (patch) | |
tree | 2e80472fd9d248f3631903aaf2282f7e0831a075 /apps/mu.subx | |
parent | 5a6d2d0db7ccc1d6b09ce898e3b57f62a5b1b787 (diff) | |
download | mu-d292196ff5ab9f103364e05c42a1edc03dc1b5ab.tar.gz |
6529 - don't let `addr`s escape functions
I've gone back and forth on this. I initially disallowed this, then allowed it because I forgot why I disallowed it. The reason to disallow it: if you return an `addr` to a variable allocated on the stack, the space might be reused for a different type, which violates type-safety. And once you can reinterpret bits of one type as another you lose memory-safety as well. This has some interesting implications for Mu programs; certain kinds of helper functions become impossible to write. Now I find myself relying a lot more on scopes (and editor folding support) for abstracting details. And they won't help manage duplication. We'll see how this goes. While I'm being draconian about `addr`s on the stack, I'm still abusing `addr`s on the heap, with the expectation that future checks on reclamation will protect me. The boon and bane of stack space is that it's constantly reclaimed.
Diffstat (limited to 'apps/mu.subx')
-rw-r--r-- | apps/mu.subx | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/apps/mu.subx b/apps/mu.subx index 70ad482d..cd08466e 100644 --- a/apps/mu.subx +++ b/apps/mu.subx @@ -4638,6 +4638,9 @@ $parse-mu:error2: # ✓ fn foo x: int { # ✓ fn foo x: int { # ✓ fn foo x: int -> y/eax: int { +# TODO: +# disallow outputs of type `(... addr ...)` +# disallow inputs of type `(... addr ... addr ...)` populate-mu-function-header: # first-line: (addr stream byte), out: (addr function), vars: (addr stack live-var), err: (addr buffered-file), ed: (addr exit-descriptor) # pseudocode: # var name: slice |