Config as: accepts one spelling per compiler, no aliases

Context

CompilerType (crates/bear/src/config/types.rs) used to accept many config as: spellings per compiler family through hand-written #[serde(alias = ...)] lists, plus whatever #[serde(rename_all = "lowercase")] happened to squash a Rust variant name into when no alias was written (for example clangcl for ClangCl, with no separator between the words). This alias surface was never designed as a feature; it accumulated over time as each compiler family was added, with no record of who relied on which spelling.

While building the wrapper-YAML plan (adding ccache/distcc/ sccache/icecc as YAML-defined compiler launchers), two related ideas were drafted in full and then reversed on 2026-07-20:

• Replacing the hand-aliases with a YAML-driven aliases: list per compiler file, generating an alias map at codegen time. This was reviewed and discarded: the alias surface itself was not worth keeping. No user demand for any specific alias was on record, and generating a bigger version of an undesigned surface does not fix the underlying problem.
• Re-spelling the seven multi-word ids to a hyphenated form (for example clang_cl to clang-cl) for nicer --print-compilers output. This was drafted as a follow-on to the aliases idea and discarded for the same reason: once no aliases exist, printing anything other than the literal id is a cosmetic, unexplained mutation of the value that is supposed to be the source of truth.

Decision

Each compiler family accepts exactly one config as: spelling: its YAML compiler.id, verbatim, everywhere that spelling appears (the YAML file, the generated recognition data, --print-compilers output, and config parsing). No aliases, no re-spelling. The config deserializer validates an as: value against the generated set of ids and rejects anything else, naming the accepted values; there is no alias map and no per-family spelling to hand-maintain (see compiler-family-definition for how the family set became generated data).

Compiler launchers are the one exception: a launcher file (ccache, distcc, sccache, icecc) declares no family identity -- dispatch is uniform -- so it has no compiler.id to draw a canonical spelling from. Its launcher basename is still an accepted as: value (all four resolve to the one wrapper kind), drawn from the same generated data as every other spelling; no launcher spelling is hand-wired.

Consequences

• Breaking change for any config pinning a non-canonical spelling (llvm, gnu, clangcl, intel-cc, and similar dropped aliases). There is no static changelog file in this repository; a release-notes line for this change is drafted from commit history at release time (see the release skill).
• Simpler code: no generated alias map, and no per-variant alias list to keep in sync as compiler families are added or renamed.
• --print-compilers's as column is now always exactly the string a user must type in as: for that family; there is no display transform anywhere in the pipeline to keep in sync with the parser.
• A future contributor proposing to re-add aliases, or to hyphenate ids for display, should read this entry first: both were drafted in full and discarded, not merely left undone.

References

• Requirement: recognition-compiler-launchers (the closest governing requirement; there was never a requirement formalizing the as: alias contract itself, since it was undocumented behavior that accumulated rather than a contract anyone shipped deliberately, which is part of why dropping it was acceptable).