Auto merge of #139594 - compiler-errors:if-cause, r= · rust-lang/rust@a62fc50 (original) (raw)

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`use rustc_errors::{Applicability, Diag};

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`use rustc_hir::def::{CtorOf, DefKind, Res};

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`use rustc_hir::def_id::LocalDefId;

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use rustc_hir::{self as hir, ExprKind, PatKind};

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use rustc_hir::{self as hir, ExprKind, HirId, PatKind};

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`use rustc_hir_pretty::ty_to_string;

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`use rustc_middle::ty::{self, Ty};

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`use rustc_span::Span;

`@@ -412,89 +412,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {

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`pub(crate) fn if_cause(

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`&self,

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span: Span,

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cond_span: Span,

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expr_id: HirId,

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`then_expr: &'tcx hir::Expr<'tcx>,

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`else_expr: &'tcx hir::Expr<'tcx>,

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`then_ty: Ty<'tcx>,

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`else_ty: Ty<'tcx>,

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`tail_defines_return_position_impl_trait: Option,

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`) -> ObligationCause<'tcx> {

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let mut outer_span = if self.tcx.sess.source_map().is_multiline(span) {

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`` -

// The if/else isn't in one line in the output, include some context to make it

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// clear it is an if/else expression:

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// ```

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// LL | let x = if true {

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// | _____________-

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// LL || 10i32

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// || ----- expected because of this

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// LL || } else {

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// LL || 10u32

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`` -

// || ^^^^^ expected i32, found u32

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// LL || };

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`` -

// ||_____- if and else have incompatible types

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// ```

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Some(span)

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} else {

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// The entire expression is in one line, only point at the arms

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// ```

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// LL | let x = if true { 10i32 } else { 10u32 };

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`` -

// | ----- ^^^^^ expected i32, found u32

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// | |

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// | expected because of this

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// ```

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None

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};

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-

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`let (error_sp, else_id) = if let ExprKind::Block(block, _) = &else_expr.kind {

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`let block = block.innermost_block();

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-

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// Avoid overlapping spans that aren't as readable:

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// ```

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// 2 | let x = if true {

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// | _____________-

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// 3 | | 3

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// | | - expected because of this

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// 4 | | } else {

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// | |____________^

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// 5 | ||

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// 6 | || };

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// | || ^

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// | ||_____|

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// | |______if and else have incompatible types

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`` -

// | expected integer, found ()

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// ```

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// by not pointing at the entire expression:

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// ```

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// 2 | let x = if true {

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`` -

// | ------- if and else have incompatible types

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// 3 | 3

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// | - expected because of this

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// 4 | } else {

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// | ____________^

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// 5 | |

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// 6 | | };

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`` -

// | |_____^ expected integer, found ()

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// ```

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if block.expr.is_none()

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&& block.stmts.is_empty()

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&& let Some(outer_span) = &mut outer_span

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&& let Some(cond_span) = cond_span.find_ancestor_inside(*outer_span)

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{

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*outer_span = outer_span.with_hi(cond_span.hi())

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}

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-

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`(self.find_block_span(block), block.hir_id)

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`} else {

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`(else_expr.span, else_expr.hir_id)

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`};

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`let then_id = if let ExprKind::Block(block, _) = &then_expr.kind {

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`let block = block.innermost_block();

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// Exclude overlapping spans

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if block.expr.is_none() && block.stmts.is_empty() {

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outer_span = None;

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}

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` block.hir_id

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`} else {

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` then_expr.hir_id

`@@ -504,11 +437,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {

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`self.cause(

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` error_sp,

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`ObligationCauseCode::IfExpression(Box::new(IfExpressionCause {

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expr_id,

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` else_id,

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` then_id,

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` then_ty,

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` else_ty,

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outer_span,

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` tail_defines_return_position_impl_trait,

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`})),

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