1 files changed, 65 insertions, 0 deletions
diff --git a/tests/run-make/llvm-location-discriminator-limit-dummy-span/rmake.rs b/tests/run-make/llvm-location-discriminator-limit-dummy-span/rmake.rs
new file mode 100644
index 00000000000..2727effe818
--- /dev/null
+++ b/tests/run-make/llvm-location-discriminator-limit-dummy-span/rmake.rs
@@ -0,0 +1,65 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/135332>.
+//!
+//! We can't simply drop debuginfo location spans when LLVM's location discriminator value limit is
+//! reached. Otherwise, with `-Z verify-llvm-ir` and fat LTO, LLVM will report a broken module for
+//!
+//! ```text
+//! inlinable function call in a function with debug info must have a !dbg location
+//! ```
+
+//@ ignore-cross-compile
+//@ needs-dynamic-linking
+//@ only-nightly (requires unstable rustc flag)
+
+#![deny(warnings)]
+
+use run_make_support::{dynamic_lib_name, rfs, rust_lib_name, rustc};
+
+// Synthesize a function that will have a large (`n`) number of functions
+// MIR-inlined into it. When combined with a proc-macro, all of these inline
+// callsites will have the same span, forcing rustc to use the DWARF
+// discriminator to distinguish between them. LLVM's capacity to store that
+// discriminator is not infinite (currently it allocates 12 bits for a
+// maximum value of 4096) so if this function gets big enough rustc's error
+// handling path will be exercised.
+fn generate_program(n: u32) -> String {
+    let mut program = String::from("pub type BigType = Vec<Vec<String>>;\n\n");
+    program.push_str("pub fn big_function() -> BigType {\n");
+    program.push_str("    vec![\n");
+    for i in 1..=n {
+        program.push_str(&format!("vec![\"string{}\".to_owned()],\n", i));
+    }
+    program.push_str("    ]\n");
+    program.push_str("}\n");
+    program
+}
+
+fn main() {
+    // The reported threshold is around 1366 (4096/3), but let's bump it to
+    // around 1500 to be less sensitive.
+    rfs::write("generated.rs", generate_program(1500));
+
+    rustc()
+        .input("proc.rs")
+        .crate_type("proc-macro")
+        .edition("2021")
+        .arg("-Cdebuginfo=line-tables-only")
+        .run();
+    rustc()
+        .extern_("proc", dynamic_lib_name("proc"))
+        .input("other.rs")
+        .crate_type("rlib")
+        .edition("2021")
+        .opt_level("3")
+        .arg("-Cdebuginfo=line-tables-only")
+        .run();
+    rustc()
+        .extern_("other", rust_lib_name("other"))
+        .input("main.rs")
+        .edition("2021")
+        .opt_level("3")
+        .arg("-Cdebuginfo=line-tables-only")
+        .arg("-Clto=fat")
+        .arg("-Zverify-llvm-ir")
+        .run();
+}