rust-lang/rust — pull request #19890 by pnkfelix (2014-12-15 21:26:22+00:00)
Title: graphviz drawing of constraints for region inference

Added `-Z print-region-graph` debugging option; produces graphviz visualization of region inference constraint graph.

Optionally uses environment variables `RUST_REGION_GRAPH=` and `RUST_REGION_GRAPH_NODE=` to select which file to output to and which AST node to print.