2 files changed, 30 insertions, 0 deletions
diff --git a/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.rs b/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.rs
new file mode 100644
index 000000000..7f6758f47
--- /dev/null
+++ b/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.rs
@@ -0,0 +1,19 @@
+// ignore-tidy-linelength
+
+// Regression test for #107745.
+// Previously need_type_info::update_infer_source will consider expressions originating from
+// macro expressions as candiate "previous sources". This unfortunately can mean that
+// for macros expansions such as `format!()` internal implementation details can leak, such as:
+//
+// ```
+// error[E0282]: type annotations needed
+// --> src/main.rs:2:22
+//  |
+//2 |     println!("{:?}", []);
+//  |                      ^^ cannot infer type of the type parameter `T` declared on the associated function `new_debug`
+// ```
+
+fn main() {
+    println!("{:?}", []);
+    //~^ ERROR type annotations needed
+}
diff --git a/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.stderr b/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.stderr
new file mode 100644
index 000000000..464655bbc
--- /dev/null
+++ b/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.stderr
@@ -0,0 +1,11 @@
+error[E0282]: type annotations needed
+  --> $DIR/issue-107745-avoid-expr-from-macro-expansion.rs:17:22
+   |
+LL |     println!("{:?}", []);
+   |                      ^^ cannot infer type
+   |
+   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.