Avoid a bogus THIR span for let x = offset_of!(..)

Author: Zalathar

compiler/rustc_mir_build/src/thir/cx/block.rs

@@ -75,8 +75,13 @@ impl<'tcx> ThirBuildCx<'tcx> {
                         debug!(?pattern);
 
                         let span = match local.init {
-                            Some(init) => local.span.with_hi(init.span.hi()),
-                            None => local.span,
+                            Some(init)
+                                if let Some(init_span) =
+                                    init.span.find_ancestor_inside_same_ctxt(local.span) =>
+                            {
+                                local.span.with_hi(init_span.hi())
+                            }
+                            Some(_) | None => local.span,
                         };
                         let stmt = Stmt {
                             kind: StmtKind::Let {

tests/ui/span/let-offset-of.stderr

@@ -9,6 +9,10 @@ LL |     if let x = offset_of!(Foo, field) {}
    = note: `#[warn(irrefutable_let_patterns)]` on by default
 
 warning: irrefutable `let...else` pattern
+  --> $DIR/let-offset-of.rs:17:5
+   |
+LL |     let x = offset_of!(Foo, field) else { return; };
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this pattern will always match, so the `else` clause is useless
    = help: consider removing the `else` clause

tests/ui/thir-print/offset_of.stdout

@@ -68,7 +68,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::concrete).10)
-                                            span: $DIR/offset_of.rs:37:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:37:5: 37:33 (#0)
                                         }
                                     }
                                     Stmt {
@@ -117,7 +117,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::concrete).20)
-                                            span: $DIR/offset_of.rs:38:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:38:5: 38:33 (#0)
                                         }
                                     }
                                     Stmt {
@@ -166,7 +166,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::concrete).30)
-                                            span: $DIR/offset_of.rs:39:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:39:5: 39:34 (#0)
                                         }
                                     }
                                     Stmt {
@@ -215,7 +215,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::concrete).40)
-                                            span: $DIR/offset_of.rs:40:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:40:5: 40:36 (#0)
                                         }
                                     }
                                     Stmt {
@@ -264,7 +264,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::concrete).50)
-                                            span: $DIR/offset_of.rs:41:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:41:5: 41:36 (#0)
                                         }
                                     }
                                 ]
@@ -864,7 +864,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::generic).12)
-                                            span: $DIR/offset_of.rs:45:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:45:5: 45:37 (#0)
                                         }
                                     }
                                     Stmt {
@@ -913,7 +913,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::generic).24)
-                                            span: $DIR/offset_of.rs:46:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:46:5: 46:37 (#0)
                                         }
                                     }
                                     Stmt {
@@ -962,7 +962,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::generic).36)
-                                            span: $DIR/offset_of.rs:47:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:47:5: 47:37 (#0)
                                         }
                                     }
                                     Stmt {
@@ -1011,7 +1011,7 @@ body:
                                             )
                                             else_block: None
                                             hir_id: HirId(DefId(offset_of::generic).48)
-                                            span: $DIR/offset_of.rs:48:5: 1445:57 (#0)
+                                            span: $DIR/offset_of.rs:48:5: 48:37 (#0)
                                         }
                                     }
                                 ]