Capturing a frozen value is a Read
If a value is known to be frozen (or potentially frozen), then it doesn't need to be considered 'captured' since no mutation can occur via aliasing.
Joe Savona committed
Feb 14, 2023 at 09:33 UTC
6b67f597a6bc286fdf716c6840ece0c56997aba1
5 files changed
+329
-1
compiler/forget/src/Inference/InferReferenceEffects.ts
+8
-1
@@ -308,7 +308,14 @@ class Environment {
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break;
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}
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case Effect.Capture: {
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- effect = Effect.Capture;
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+ if (
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+ valueKind === ValueKind.Frozen ||
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+ valueKind === ValueKind.MaybeFrozen
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+ ) {
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+ effect = Effect.Read;
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+ } else {
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+ effect = Effect.Capture;
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+ }
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break;
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}
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case Effect.Read: {
compiler/forget/src/__tests__/fixtures/hir/same-variable-as-dep-and-redeclare-maybe-frozen.expect.md
new
+127
@@ -0,0 +1,127 @@
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+
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+## Input
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+
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+```javascript
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+// note: comments are for the ideal scopes, not what is currently
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+// emitted
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+function foo(props) {
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+ // scope 0: deps=[props.a] decl=[x] reassign=none
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+ let x = [];
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+ x.push(props.a);
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+
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+ // scope 1: deps=[x] decl=[header] reassign=none
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+ const header = props.showHeader ? <div>{x}</div> : null;
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+
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+ // scope 2:
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+ // deps=[x, props.b, props.c]
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+ // decl=none
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+ // reassign=[x]
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+ const y = [x]; // y depends on the earlier x
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+ x = []; // x reassigned
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+ y.push(props.b); // interleaved mutation of x/y
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+ x.push(props.c); // interleaved mutation
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+
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+ // scope 3 ...
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+ const content = (
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+ <div>
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+ {x}
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+ {y}
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+ </div>
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+ );
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+
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+ // scope 4 ...
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+ return (
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+ <>
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+ {header}
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+ {content}
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+ </>
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+ );
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+}
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+
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+```
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+
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+## Code
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+
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+```javascript
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+// note: comments are for the ideal scopes, not what is currently
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+// emitted
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+function foo(props) {
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+ const $ = React.unstable_useMemoCache();
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+ const c_0 = $[0] !== props.a;
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+ let x;
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+ if (c_0) {
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+ x = [];
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+ x.push(props.a);
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+ $[0] = props.a;
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+ $[1] = x;
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+ } else {
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+ x = $[1];
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+ }
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+ const c_2 = $[2] !== props;
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+ const c_3 = $[3] !== x;
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+ let t0;
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+ if (c_2 || c_3) {
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+ t0 = props.showHeader ? <div>{x}</div> : null;
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+ $[2] = props;
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+ $[3] = x;
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+ $[4] = t0;
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+ } else {
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+ t0 = $[4];
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+ }
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+ const header = t0;
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+ const c_5 = $[5] !== x;
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+ const c_6 = $[6] !== props.b;
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+ const c_7 = $[7] !== props.c;
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+ let x$0;
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+ let y;
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+ if (c_5 || c_6 || c_7) {
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+ y = [x];
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+ x$0 = [];
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+ y.push(props.b);
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+ x$0.push(props.c);
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+ $[5] = x;
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+ $[6] = props.b;
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+ $[7] = props.c;
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+ $[8] = x$0;
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+ $[9] = y;
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+ } else {
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+ x$0 = $[8];
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+ y = $[9];
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+ }
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+ const c_10 = $[10] !== x$0;
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+ const c_11 = $[11] !== y;
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+ let content;
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+ if (c_10 || c_11) {
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+ content = (
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+ <div>
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+ {x$0}
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+ {y}
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+ </div>
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+ );
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+ $[10] = x$0;
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+ $[11] = y;
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+ $[12] = content;
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+ } else {
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+ content = $[12];
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+ }
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+ const c_13 = $[13] !== header;
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+ const c_14 = $[14] !== content;
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+ let t1;
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+ if (c_13 || c_14) {
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+ t1 = (
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+ <>
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+ {header}
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+ {content}
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+ </>
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+ );
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+ $[13] = header;
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+ $[14] = content;
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+ $[15] = t1;
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+ } else {
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+ t1 = $[15];
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+ }
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+ return t1;
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+}
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+
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+```
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+
\ No newline at end of file
compiler/forget/src/__tests__/fixtures/hir/same-variable-as-dep-and-redeclare-maybe-frozen.js
new
+35
@@ -0,0 +1,35 @@
1
+// note: comments are for the ideal scopes, not what is currently
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+// emitted
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+function foo(props) {
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+ // scope 0: deps=[props.a] decl=[x] reassign=none
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+ let x = [];
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+ x.push(props.a);
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+
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+ // scope 1: deps=[x] decl=[header] reassign=none
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+ const header = props.showHeader ? <div>{x}</div> : null;
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+
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+ // scope 2:
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+ // deps=[x, props.b, props.c]
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+ // decl=none
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+ // reassign=[x]
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+ const y = [x]; // y depends on the earlier x
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+ x = []; // x reassigned
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+ y.push(props.b); // interleaved mutation of x/y
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+ x.push(props.c); // interleaved mutation
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+
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+ // scope 3 ...
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+ const content = (
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+ <div>
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+ {x}
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+ {y}
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+ </div>
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+ );
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+
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+ // scope 4 ...
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+ return (
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+ <>
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+ {header}
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+ {content}
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+ </>
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+ );
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+}
compiler/forget/src/__tests__/fixtures/hir/same-variable-as-dep-and-redeclare.expect.md
new
+124
@@ -0,0 +1,124 @@
1
+
2
+## Input
3
+
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+```javascript
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+// note: comments are for the ideal scopes, not what is currently
6
+// emitted
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+function foo(props) {
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+ // scope 0: deps=[props.a] decl=[x] reassign=none
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+ let x = [];
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+ x.push(props.a);
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+
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+ // scope 1: deps=[x] decl=[header] reassign=none
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+ const header = <div>{x}</div>;
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+
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+ // scope 2:
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+ // deps=[x, props.b, props.c]
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+ // decl=none
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+ // reassign=[x]
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+ const y = [x]; // y depends on the earlier x
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+ x = []; // x reassigned
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+ y.push(props.b); // interleaved mutation of x/y
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+ x.push(props.c); // interleaved mutation
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+
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+ // scope 3 ...
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+ const content = (
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+ <div>
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+ {x}
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+ {y}
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+ </div>
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+ );
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+
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+ // scope 4 ...
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+ return (
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+ <>
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+ {header}
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+ {content}
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+ </>
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+ );
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+}
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+
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+```
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+
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+## Code
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+
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+```javascript
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+// note: comments are for the ideal scopes, not what is currently
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+// emitted
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+function foo(props) {
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+ const $ = React.unstable_useMemoCache();
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+ const c_0 = $[0] !== props.a;
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+ let x;
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+ if (c_0) {
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+ x = [];
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+ x.push(props.a);
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+ $[0] = props.a;
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+ $[1] = x;
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+ } else {
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+ x = $[1];
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+ }
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+ const c_2 = $[2] !== x;
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+ let header;
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+ if (c_2) {
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+ header = <div>{x}</div>;
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+ $[2] = x;
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+ $[3] = header;
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+ } else {
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+ header = $[3];
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+ }
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+ const c_4 = $[4] !== x;
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+ const c_5 = $[5] !== props.b;
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+ const c_6 = $[6] !== props.c;
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+ let x$0;
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+ let y;
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+ if (c_4 || c_5 || c_6) {
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+ y = [x];
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+ x$0 = [];
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+ y.push(props.b);
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+ x$0.push(props.c);
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+ $[4] = x;
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+ $[5] = props.b;
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+ $[6] = props.c;
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+ $[7] = x$0;
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+ $[8] = y;
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+ } else {
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+ x$0 = $[7];
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+ y = $[8];
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+ }
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+ const c_9 = $[9] !== x$0;
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+ const c_10 = $[10] !== y;
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+ let content;
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+ if (c_9 || c_10) {
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+ content = (
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+ <div>
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+ {x$0}
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+ {y}
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+ </div>
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+ );
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+ $[9] = x$0;
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+ $[10] = y;
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+ $[11] = content;
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+ } else {
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+ content = $[11];
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+ }
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+ const c_12 = $[12] !== header;
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+ const c_13 = $[13] !== content;
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+ let t0;
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+ if (c_12 || c_13) {
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+ t0 = (
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+ <>
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+ {header}
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+ {content}
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+ </>
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+ );
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+ $[12] = header;
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+ $[13] = content;
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+ $[14] = t0;
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+ } else {
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+ t0 = $[14];
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+ }
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+ return t0;
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+}
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+
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+```
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+
\ No newline at end of file
compiler/forget/src/__tests__/fixtures/hir/same-variable-as-dep-and-redeclare.js
new
+35
@@ -0,0 +1,35 @@
1
+// note: comments are for the ideal scopes, not what is currently
2
+// emitted
3
+function foo(props) {
4
+ // scope 0: deps=[props.a] decl=[x] reassign=none
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+ let x = [];
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+ x.push(props.a);
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+
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+ // scope 1: deps=[x] decl=[header] reassign=none
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+ const header = <div>{x}</div>;
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+
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+ // scope 2:
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+ // deps=[x, props.b, props.c]
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+ // decl=none
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+ // reassign=[x]
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+ const y = [x]; // y depends on the earlier x
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+ x = []; // x reassigned
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+ y.push(props.b); // interleaved mutation of x/y
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+ x.push(props.c); // interleaved mutation
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+
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+ // scope 3 ...
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+ const content = (
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+ <div>
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+ {x}
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+ {y}
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+ </div>
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+ );
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+
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+ // scope 4 ...
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+ return (
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+ <>
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+ {header}
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+ {content}
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+ </>
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+ );
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+}