mirror of
https://github.com/facebook/react.git
synced 2025-11-01 09:12:30 +00:00
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.
This commit is contained in:
Joe Savona
@@ -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: {
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+127
@@ -0,0 +1,127 @@
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## Input
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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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// scope 1: deps=[x] decl=[header] reassign=none
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const header = props.showHeader ? <div>{x}</div> : null;
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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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// 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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// 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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## Code
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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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+35
@@ -0,0 +1,35 @@
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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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// scope 1: deps=[x] decl=[header] reassign=none
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const header = props.showHeader ? <div>{x}</div> : null;
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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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// 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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// 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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+124
@@ -0,0 +1,124 @@
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## Input
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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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// scope 1: deps=[x] decl=[header] reassign=none
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const header = <div>{x}</div>;
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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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// 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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// 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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## Code
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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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@@ -0,0 +1,35 @@
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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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// scope 1: deps=[x] decl=[header] reassign=none
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const header = <div>{x}</div>;
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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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// 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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// 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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Block a user