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Rollup merge of #73182 - Aaron1011:feature/call-fn-span, r=matthewjasper
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Track span of function in method calls, and use this in #[track_caller]

Fixes #69977

When we parse a chain of method calls like `foo.a().b().c()`, each
`MethodCallExpr` gets assigned a span that starts at the beginning of
the call chain (`foo`). While this is useful for diagnostics, it means
that `Location::caller` will return the same location for every call
in a call chain.

This PR makes us separately record the span of the function name and
arguments for a method call (e.g. `b()` in `foo.a().b().c()`). This
`Span` is passed through HIR lowering and MIR building to
`TerminatorKind::Call`, where it is used in preference to
`Terminator.source_info.span` when determining `Location::caller`.

This new span is also useful for diagnostics where we want to emphasize
a particular method call - for an example, see
#72389 (comment)
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Dylan-DPC authored Jun 11, 2020
2 parents b341115 + 9d36fa3 commit 84b9145
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4 changes: 3 additions & 1 deletion src/librustc_ast/ast.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1174,7 +1174,9 @@ pub enum ExprKind {
/// and the remaining elements are the rest of the arguments.
/// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
/// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d])`.
MethodCall(PathSegment, Vec<P<Expr>>),
/// This `Span` is the span of the function, without the dot and receiver
/// (e.g. `foo(a, b)` in `x.foo(a, b)`
MethodCall(PathSegment, Vec<P<Expr>>, Span),
/// A tuple (e.g., `(a, b, c, d)`).
Tup(Vec<P<Expr>>),
/// A binary operation (e.g., `a + b`, `a * b`).
Expand Down
3 changes: 2 additions & 1 deletion src/librustc_ast/mut_visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1111,11 +1111,12 @@ pub fn noop_visit_expr<T: MutVisitor>(
vis.visit_expr(f);
visit_exprs(args, vis);
}
ExprKind::MethodCall(PathSegment { ident, id, args }, exprs) => {
ExprKind::MethodCall(PathSegment { ident, id, args }, exprs, span) => {
vis.visit_ident(ident);
vis.visit_id(id);
visit_opt(args, |args| vis.visit_generic_args(args));
visit_exprs(exprs, vis);
vis.visit_span(span);
}
ExprKind::Binary(_binop, lhs, rhs) => {
vis.visit_expr(lhs);
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_ast/util/parser.rs
Original file line number Diff line number Diff line change
Expand Up @@ -394,7 +394,7 @@ pub fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
contains_exterior_struct_lit(&x)
}

ast::ExprKind::MethodCall(.., ref exprs) => {
ast::ExprKind::MethodCall(.., ref exprs, _) => {
// X { y: 1 }.bar(...)
contains_exterior_struct_lit(&exprs[0])
}
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_ast/visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -726,7 +726,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
visitor.visit_expr(callee_expression);
walk_list!(visitor, visit_expr, arguments);
}
ExprKind::MethodCall(ref segment, ref arguments) => {
ExprKind::MethodCall(ref segment, ref arguments, _span) => {
visitor.visit_path_segment(expression.span, segment);
walk_list!(visitor, visit_expr, arguments);
}
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_ast_lowering/expr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
let f = self.lower_expr(f);
hir::ExprKind::Call(f, self.lower_exprs(args))
}
ExprKind::MethodCall(ref seg, ref args) => {
ExprKind::MethodCall(ref seg, ref args, span) => {
let hir_seg = self.arena.alloc(self.lower_path_segment(
e.span,
seg,
Expand All @@ -50,7 +50,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
None,
));
let args = self.lower_exprs(args);
hir::ExprKind::MethodCall(hir_seg, seg.ident.span, args)
hir::ExprKind::MethodCall(hir_seg, seg.ident.span, args, span)
}
ExprKind::Binary(binop, ref lhs, ref rhs) => {
let binop = self.lower_binop(binop);
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_ast_pretty/pprust.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1818,7 +1818,7 @@ impl<'a> State<'a> {
ast::ExprKind::Call(ref func, ref args) => {
self.print_expr_call(func, &args[..]);
}
ast::ExprKind::MethodCall(ref segment, ref args) => {
ast::ExprKind::MethodCall(ref segment, ref args, _) => {
self.print_expr_method_call(segment, &args[..]);
}
ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
Expand Down
12 changes: 10 additions & 2 deletions src/librustc_codegen_ssa/mir/block.rs
Original file line number Diff line number Diff line change
Expand Up @@ -530,6 +530,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
args: &Vec<mir::Operand<'tcx>>,
destination: &Option<(mir::Place<'tcx>, mir::BasicBlock)>,
cleanup: Option<mir::BasicBlock>,
fn_span: Span,
) {
let span = terminator.source_info.span;
// Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
Expand Down Expand Up @@ -634,7 +635,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {

if intrinsic == Some("caller_location") {
if let Some((_, target)) = destination.as_ref() {
let location = self.get_caller_location(&mut bx, span);
let location = self.get_caller_location(&mut bx, fn_span);

if let ReturnDest::IndirectOperand(tmp, _) = ret_dest {
location.val.store(&mut bx, tmp);
Expand Down Expand Up @@ -798,7 +799,12 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
args.len() + 1,
"#[track_caller] fn's must have 1 more argument in their ABI than in their MIR",
);
let location = self.get_caller_location(&mut bx, span);
let location = self.get_caller_location(&mut bx, fn_span);
debug!(
"codegen_call_terminator({:?}): location={:?} (fn_span {:?})",
terminator, location, fn_span
);

let last_arg = fn_abi.args.last().unwrap();
self.codegen_argument(&mut bx, location, &mut llargs, last_arg);
}
Expand Down Expand Up @@ -1016,6 +1022,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
ref destination,
cleanup,
from_hir_call: _,
fn_span,
} => {
self.codegen_call_terminator(
helper,
Expand All @@ -1025,6 +1032,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
args,
destination,
cleanup,
fn_span,
);
}
mir::TerminatorKind::GeneratorDrop | mir::TerminatorKind::Yield { .. } => {
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_expand/build.rs
Original file line number Diff line number Diff line change
Expand Up @@ -272,7 +272,7 @@ impl<'a> ExtCtxt<'a> {
) -> P<ast::Expr> {
args.insert(0, expr);
let segment = ast::PathSegment::from_ident(ident.with_span_pos(span));
self.expr(span, ast::ExprKind::MethodCall(segment, args))
self.expr(span, ast::ExprKind::MethodCall(segment, args, span))
}
pub fn expr_block(&self, b: P<ast::Block>) -> P<ast::Expr> {
self.expr(b.span, ast::ExprKind::Block(b, None))
Expand Down
6 changes: 4 additions & 2 deletions src/librustc_hir/hir.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1371,7 +1371,7 @@ pub struct Expr<'hir> {

// `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(target_arch = "x86_64")]
rustc_data_structures::static_assert_size!(Expr<'static>, 64);
rustc_data_structures::static_assert_size!(Expr<'static>, 72);

impl Expr<'_> {
pub fn precedence(&self) -> ExprPrecedence {
Expand Down Expand Up @@ -1568,12 +1568,14 @@ pub enum ExprKind<'hir> {
/// and the remaining elements are the rest of the arguments.
/// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
/// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d])`.
/// The final `Span` represents the span of the function and arguments
/// (e.g. `foo::<Bar, Baz>(a, b, c, d)` in `x.foo::<Bar, Baz>(a, b, c, d)`
///
/// To resolve the called method to a `DefId`, call [`type_dependent_def_id`] with
/// the `hir_id` of the `MethodCall` node itself.
///
/// [`type_dependent_def_id`]: ../ty/struct.TypeckTables.html#method.type_dependent_def_id
MethodCall(&'hir PathSegment<'hir>, Span, &'hir [Expr<'hir>]),
MethodCall(&'hir PathSegment<'hir>, Span, &'hir [Expr<'hir>], Span),
/// A tuple (e.g., `(a, b, c, d)`).
Tup(&'hir [Expr<'hir>]),
/// A binary operation (e.g., `a + b`, `a * b`).
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_hir/intravisit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1090,7 +1090,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
visitor.visit_expr(callee_expression);
walk_list!(visitor, visit_expr, arguments);
}
ExprKind::MethodCall(ref segment, _, arguments) => {
ExprKind::MethodCall(ref segment, _, arguments, _) => {
visitor.visit_path_segment(expression.span, segment);
walk_list!(visitor, visit_expr, arguments);
}
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_hir_pretty/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1308,7 +1308,7 @@ impl<'a> State<'a> {
hir::ExprKind::Call(ref func, ref args) => {
self.print_expr_call(&func, args);
}
hir::ExprKind::MethodCall(ref segment, _, ref args) => {
hir::ExprKind::MethodCall(ref segment, _, ref args, _) => {
self.print_expr_method_call(segment, args);
}
hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
Expand Down Expand Up @@ -2491,7 +2491,7 @@ fn contains_exterior_struct_lit(value: &hir::Expr<'_>) -> bool {
contains_exterior_struct_lit(&x)
}

hir::ExprKind::MethodCall(.., ref exprs) => {
hir::ExprKind::MethodCall(.., ref exprs, _) => {
// `X { y: 1 }.bar(...)`
contains_exterior_struct_lit(&exprs[0])
}
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_infer/infer/error_reporting/need_type_info.rs
Original file line number Diff line number Diff line change
Expand Up @@ -107,7 +107,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindHirNodeVisitor<'a, 'tcx> {
}

fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
if let ExprKind::MethodCall(_, call_span, exprs) = expr.kind {
if let ExprKind::MethodCall(_, call_span, exprs, _) = expr.kind {
if call_span == self.target_span
&& Some(self.target)
== self.infcx.in_progress_tables.and_then(|tables| {
Expand Down Expand Up @@ -294,7 +294,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// 3 | let _ = x.sum() as f64;
// | ^^^ cannot infer type for `S`
span
} else if let Some(ExprKind::MethodCall(_, call_span, _)) =
} else if let Some(ExprKind::MethodCall(_, call_span, _, _)) =
local_visitor.found_method_call.map(|e| &e.kind)
{
// Point at the call instead of the whole expression:
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_lint/array_into_iter.rs
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ declare_lint_pass!(
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ArrayIntoIter {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'tcx>) {
// We only care about method call expressions.
if let hir::ExprKind::MethodCall(call, span, args) = &expr.kind {
if let hir::ExprKind::MethodCall(call, span, args, _) = &expr.kind {
if call.ident.name != sym::into_iter {
return;
}
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_lint/builtin.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1899,7 +1899,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidValue {
}
}
}
} else if let hir::ExprKind::MethodCall(_, _, ref args) = expr.kind {
} else if let hir::ExprKind::MethodCall(_, _, ref args, _) = expr.kind {
// Find problematic calls to `MaybeUninit::assume_init`.
let def_id = cx.tables.type_dependent_def_id(expr.hir_id)?;
if cx.tcx.is_diagnostic_item(sym::assume_init, def_id) {
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_lint/unused.rs
Original file line number Diff line number Diff line change
Expand Up @@ -526,7 +526,7 @@ trait UnusedDelimLint {
let (args_to_check, ctx) = match *call_or_other {
Call(_, ref args) => (&args[..], UnusedDelimsCtx::FunctionArg),
// first "argument" is self (which sometimes needs delims)
MethodCall(_, ref args) => (&args[1..], UnusedDelimsCtx::MethodArg),
MethodCall(_, ref args, _) => (&args[1..], UnusedDelimsCtx::MethodArg),
// actual catch-all arm
_ => {
return;
Expand Down
3 changes: 3 additions & 0 deletions src/librustc_middle/mir/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1131,6 +1131,9 @@ pub enum TerminatorKind<'tcx> {
/// `true` if this is from a call in HIR rather than from an overloaded
/// operator. True for overloaded function call.
from_hir_call: bool,
/// This `Span` is the span of the function, without the dot and receiver
/// (e.g. `foo(a, b)` in `x.foo(a, b)`
fn_span: Span,
},

/// Jump to the target if the condition has the expected value,
Expand Down
3 changes: 2 additions & 1 deletion src/librustc_middle/mir/type_foldable.rs
Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
resume_arg: resume_arg.fold_with(folder),
drop,
},
Call { ref func, ref args, ref destination, cleanup, from_hir_call } => {
Call { ref func, ref args, ref destination, cleanup, from_hir_call, fn_span } => {
let dest =
destination.as_ref().map(|&(ref loc, dest)| (loc.fold_with(folder), dest));

Expand All @@ -52,6 +52,7 @@ impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
destination: dest,
cleanup,
from_hir_call,
fn_span,
}
}
Assert { ref cond, expected, ref msg, target, cleanup } => {
Expand Down
1 change: 1 addition & 0 deletions src/librustc_middle/mir/visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -492,6 +492,7 @@ macro_rules! make_mir_visitor {
destination,
cleanup: _,
from_hir_call: _,
fn_span: _
} => {
self.visit_operand(func, source_location);
for arg in args {
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/borrow_check/invalidation.rs
Original file line number Diff line number Diff line change
Expand Up @@ -142,6 +142,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
destination,
cleanup: _,
from_hir_call: _,
fn_span: _,
} => {
self.consume_operand(location, func);
for arg in args {
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/borrow_check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -699,6 +699,7 @@ impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tc
ref destination,
cleanup: _,
from_hir_call: _,
fn_span: _,
} => {
self.consume_operand(loc, (func, span), flow_state);
for arg in args {
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_mir/dataflow/framework/direction.rs
Original file line number Diff line number Diff line change
Expand Up @@ -467,7 +467,7 @@ impl Direction for Forward {
propagate(target, exit_state);
}

Call { cleanup, destination, ref func, ref args, from_hir_call: _ } => {
Call { cleanup, destination, ref func, ref args, from_hir_call: _, fn_span: _ } => {
if let Some(unwind) = cleanup {
if dead_unwinds.map_or(true, |dead| !dead.contains(bb)) {
propagate(unwind, exit_state);
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir/dataflow/framework/tests.rs
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@ fn mock_body() -> mir::Body<'static> {
destination: Some((dummy_place.clone(), mir::START_BLOCK)),
cleanup: None,
from_hir_call: false,
fn_span: DUMMY_SP,
},
);
block(3, mir::TerminatorKind::Return);
Expand All @@ -53,6 +54,7 @@ fn mock_body() -> mir::Body<'static> {
destination: Some((dummy_place.clone(), mir::START_BLOCK)),
cleanup: None,
from_hir_call: false,
fn_span: DUMMY_SP,
},
);

Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/dataflow/move_paths/builder.rs
Original file line number Diff line number Diff line change
Expand Up @@ -401,6 +401,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
ref destination,
cleanup: _,
from_hir_call: _,
fn_span: _,
} => {
self.gather_operand(func);
for arg in args {
Expand Down
32 changes: 23 additions & 9 deletions src/librustc_mir/interpret/intrinsics/caller_location.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use std::convert::TryFrom;

use rustc_hir::lang_items::PanicLocationLangItem;
use rustc_middle::mir::TerminatorKind;
use rustc_middle::ty::subst::Subst;
use rustc_span::{Span, Symbol};
use rustc_target::abi::LayoutOf;
Expand All @@ -14,19 +15,32 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
/// Walks up the callstack from the intrinsic's callsite, searching for the first callsite in a
/// frame which is not `#[track_caller]`.
crate fn find_closest_untracked_caller_location(&self) -> Span {
self.stack()
let frame = self
.stack()
.iter()
.rev()
// Find first non-`#[track_caller]` frame.
.find(|frame| !frame.instance.def.requires_caller_location(*self.tcx))
.find(|frame| {
debug!(
"find_closest_untracked_caller_location: checking frame {:?}",
frame.instance
);
!frame.instance.def.requires_caller_location(*self.tcx)
})
// Assert that there is always such a frame.
.unwrap()
.current_source_info()
// Assert that the frame we look at is actually executing code currently
// (`current_source_info` is None when we are unwinding and the frame does
// not require cleanup).
.unwrap()
.span
.unwrap();
let loc = frame.loc.unwrap();
let block = &frame.body.basic_blocks()[loc.block];
assert_eq!(block.statements.len(), loc.statement_index);
debug!(
"find_closest_untracked_caller_location:: got terminator {:?} ({:?})",
block.terminator(),
block.terminator().kind
);
if let TerminatorKind::Call { fn_span, .. } = block.terminator().kind {
return fn_span;
}
unreachable!();
}

/// Allocate a `const core::panic::Location` with the provided filename and line/column numbers.
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/interpret/terminator.rs
Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
destination,
ref cleanup,
from_hir_call: _from_hir_call,
fn_span: _,
} => {
let old_stack = self.frame_idx();
let old_loc = self.frame().loc;
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir/shim.rs
Original file line number Diff line number Diff line change
Expand Up @@ -460,6 +460,7 @@ impl CloneShimBuilder<'tcx> {
destination: Some((dest, next)),
cleanup: Some(cleanup),
from_hir_call: true,
fn_span: self.span,
},
false,
);
Expand Down Expand Up @@ -788,6 +789,7 @@ fn build_call_shim<'tcx>(
None
},
from_hir_call: true,
fn_span: span,
},
false,
);
Expand Down
3 changes: 2 additions & 1 deletion src/librustc_mir/transform/promote_consts.rs
Original file line number Diff line number Diff line change
Expand Up @@ -909,7 +909,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
};

match terminator.kind {
TerminatorKind::Call { mut func, mut args, from_hir_call, .. } => {
TerminatorKind::Call { mut func, mut args, from_hir_call, fn_span, .. } => {
self.visit_operand(&mut func, loc);
for arg in &mut args {
self.visit_operand(arg, loc);
Expand All @@ -925,6 +925,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
cleanup: None,
destination: Some((Place::from(new_temp), new_target)),
from_hir_call,
fn_span,
},
..terminator
};
Expand Down
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