}
if debugging_opts.mir_opt_level > 1 {
+ // Functions inlined during MIR transform can, at best, make it impossible to
+ // effectively cover inlined functions, and, at worst, break coverage map generation
+ // during LLVM codegen. For example, function counter IDs are only unique within a
+ // function. Inlining after these counters are injected can produce duplicate counters,
+ // resulting in an invalid coverage map (and ICE); so this option combination is not
+ // allowed.
early_warn(
error_format,
&format!(
- "`-Z mir-opt-level={}` (any level > 1) enables function inlining, which \
- limits the effectiveness of `-Z instrument-coverage`.",
+ "`-Z mir-opt-level={}` (or any level > 1) enables function inlining, which \
+ is incompatible with `-Z instrument-coverage`. Inlining will be disabled.",
debugging_opts.mir_opt_level,
),
);