From d765fb8fafba4f6a25e34c7568d7bc8e3be8226d Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sun, 10 Mar 2024 12:39:53 +0100 Subject: add comments explaining where post-mono const eval errors abort compilation --- compiler/rustc_codegen_ssa/src/mir/constant.rs | 6 +++--- compiler/rustc_codegen_ssa/src/mir/mod.rs | 3 ++- 2 files changed, 5 insertions(+), 4 deletions(-) (limited to 'compiler/rustc_codegen_ssa/src') diff --git a/compiler/rustc_codegen_ssa/src/mir/constant.rs b/compiler/rustc_codegen_ssa/src/mir/constant.rs index d532bd90426..ff899c50b3d 100644 --- a/compiler/rustc_codegen_ssa/src/mir/constant.rs +++ b/compiler/rustc_codegen_ssa/src/mir/constant.rs @@ -21,11 +21,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { } pub fn eval_mir_constant(&self, constant: &mir::ConstOperand<'tcx>) -> mir::ConstValue<'tcx> { - // `MirUsedCollector` visited all constants before codegen began, so if we got here there - // can be no more constants that fail to evaluate. + // `MirUsedCollector` visited all required_consts before codegen began, so if we got here + // there can be no more constants that fail to evaluate. self.monomorphize(constant.const_) .eval(self.cx.tcx(), ty::ParamEnv::reveal_all(), Some(constant.span)) - .expect("erroneous constant not captured by required_consts") + .expect("erroneous constant missed by mono item collection") } /// This is a convenience helper for `simd_shuffle_indices`. It has the precondition diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs index a6fcf1fd38c..89fd57b6d96 100644 --- a/compiler/rustc_codegen_ssa/src/mir/mod.rs +++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs @@ -211,7 +211,8 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( // It may seem like we should iterate over `required_consts` to ensure they all successfully // evaluate; however, the `MirUsedCollector` already did that during the collection phase of - // monomorphization so we don't have to do it again. + // monomorphization, and if there is an error during collection then codegen never starts -- so + // we don't have to do it again. fx.per_local_var_debug_info = fx.compute_per_local_var_debug_info(&mut start_bx); -- cgit 1.4.1-3-g733a5