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[Function builders] Add support for buildExpression(). #27716

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Merged
merged 1 commit into from
Oct 16, 2019
Merged

[Function builders] Add support for buildExpression(). #27716

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1 change: 1 addition & 0 deletions include/swift/AST/KnownIdentifiers.def
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ IDENTIFIER_(bridgeToObjectiveC)
IDENTIFIER(buildBlock)
IDENTIFIER(buildDo)
IDENTIFIER(buildEither)
IDENTIFIER(buildExpression)
IDENTIFIER(buildIf)
IDENTIFIER(callAsFunction)
IDENTIFIER(Change)
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11 changes: 9 additions & 2 deletions lib/Sema/BuilderTransform.cpp
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Expand Up @@ -169,8 +169,15 @@ class BuilderClosureVisitor
}

auto expr = node.get<Expr *>();
if (wantExpr)
expr = new (ctx) OneWayExpr(expr);
if (wantExpr) {
if (builderSupports(ctx.Id_buildExpression)) {
expr = buildCallIfWanted(expr->getLoc(), ctx.Id_buildExpression,
{ expr }, { Identifier() },
/*allowOneWay=*/true);
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I know the parameter name is existing code, but why is this "allow" one-way, since it's an unconditional instruction to make the result one-way?

Anyway, this seems like the right interaction with one-way, although arguably it would be clearer in code if that was done unconditionally as a separate step.

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It used to be conditional, and I just removed the staging flag. I can clean this up

} else {
expr = new (ctx) OneWayExpr(expr);
}
}

expressions.push_back(expr);
}
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45 changes: 45 additions & 0 deletions test/Constraints/function_builder.swift
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Expand Up @@ -316,6 +316,51 @@ func testAcceptColorTagged(b: Bool, i: Int, s: String, d: Double) {

testAcceptColorTagged(b: true, i: 17, s: "Hello", d: 3.14159)

// Use buildExpression() when it's available.
enum Component {
case string(StaticString)
case floating(Double)
case color(Color)
indirect case array([Component])
indirect case optional(Component?)
}

@_functionBuilder
struct ComponentBuilder {
static func buildExpression(_ string: StaticString) -> Component {
return .string(string)
}

static func buildExpression(_ float: Double) -> Component {
return .floating(float)
}

static func buildExpression(_ color: Color) -> Component {
return .color(color)
}

static func buildBlock(_ components: Component...) -> Component {
return .array(components)
}

static func buildIf(_ value: Component?) -> Component {
return .optional(value)
}
}

func acceptComponentBuilder(@ComponentBuilder _ body: () -> Component) {
print(body())
}

acceptComponentBuilder {
"hello"
if true {
3.14159
}
.red
}
// CHECK: array([main.Component.string("hello"), main.Component.optional(Optional(main.Component.array([main.Component.floating(3.14159)]))), main.Component.color(main.Color.red)])

// rdar://53325810

// Test that we don't have problems with expression pre-checking when
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