How to get a release build with debugging information when using cargo?

Question

The following command

$ cargo build

produces a non-optimized build with debugging information. On the contrary,

$ cargo build --release

produces an optimized build without debugging information.

Is there a way of producing an optimized build with debugging information? I need this to get meaningful profiling information.

Answer 1

As shown in the Cargo documentation, modify the release profile to include debugging symbols:

[profile.release]
debug = true

See also

• Can tests be built in release mode using Cargo?
• How to compile and run an optimized Rust program with overflow checking enabled
• Does Cargo support custom profiles?

Or basically any of the top search results for "rust profiling":

• Rust Profiling with Instruments and FlameGraph on OSX: CPU/Time
• Profiling Rust applications on Linux
• Profiling rust code with callgrind

Answer 2

Another option that I found that does not require changing Cargo.toml is to use the RUSTFLAGS environment variable:

$ RUSTFLAGS=-g cargo build --release