diff options
| -rw-r--r-- | src/librustc_metadata/locator.rs | 44 | ||||
| -rw-r--r-- | src/test/ui/rmeta-rpass.rs | 9 |
2 files changed, 45 insertions, 8 deletions
diff --git a/src/librustc_metadata/locator.rs b/src/librustc_metadata/locator.rs index 578216454f9..2157b8ce159 100644 --- a/src/librustc_metadata/locator.rs +++ b/src/librustc_metadata/locator.rs @@ -654,14 +654,36 @@ impl<'a> CrateLocator<'a> { dylibs: FxHashMap<PathBuf, PathKind>, ) -> Option<(Svh, Library)> { let mut slot = None; + // Order here matters, rmeta should come first. See comment in + // `extract_one` below. let source = CrateSource { - rlib: self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot), rmeta: self.extract_one(rmetas, CrateFlavor::Rmeta, &mut slot), + rlib: self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot), dylib: self.extract_one(dylibs, CrateFlavor::Dylib, &mut slot), }; slot.map(|(svh, metadata)| (svh, Library { source, metadata })) } + fn needs_crate_flavor(&self, flavor: CrateFlavor) -> bool { + if flavor == CrateFlavor::Dylib && self.is_proc_macro == Some(true) { + return true; + } + + // The all loop is because `--crate-type=rlib --crate-type=rlib` is + // legal and produces both inside this type. + let is_rlib = self.sess.crate_types.borrow().iter().all(|c| *c == config::CrateType::Rlib); + let needs_object_code = self.sess.opts.output_types.should_codegen(); + // If we're producing an rlib, then we don't need object code. + // Or, if we're not producing object code, then we don't need it either + // (e.g., if we're a cdylib but emitting just metadata). + if is_rlib || !needs_object_code { + flavor == CrateFlavor::Rmeta + } else { + // we need all flavors (perhaps not true, but what we do for now) + true + } + } + // Attempts to extract *one* library from the set `m`. If the set has no // elements, `None` is returned. If the set has more than one element, then // the errors and notes are emitted about the set of libraries. @@ -679,12 +701,22 @@ impl<'a> CrateLocator<'a> { let mut ret: Option<(PathBuf, PathKind)> = None; let mut error = 0; + // If we are producing an rlib, and we've already loaded metadata, then + // we should not attempt to discover further crate sources (unless we're + // locating a proc macro; exact logic is in needs_crate_flavor). This means + // that under -Zbinary-dep-depinfo we will not emit a dependency edge on + // the *unused* rlib, and by returning `None` here immediately we + // guarantee that we do indeed not use it. + // + // See also #68149 which provides more detail on why emitting the + // dependency on the rlib is a bad thing. + // + // We currenty do not verify that these other sources are even in sync, + // and this is arguably a bug (see #10786), but because reading metadata + // is quite slow (especially from dylibs) we currently do not read it + // from the other crate sources. if slot.is_some() { - // FIXME(#10786): for an optimization, we only read one of the - // libraries' metadata sections. In theory we should - // read both, but reading dylib metadata is quite - // slow. - if m.is_empty() { + if m.is_empty() || !self.needs_crate_flavor(flavor) { return None; } else if m.len() == 1 { return Some(m.into_iter().next().unwrap()); diff --git a/src/test/ui/rmeta-rpass.rs b/src/test/ui/rmeta-rpass.rs index 5a63b5b8598..173a6a394eb 100644 --- a/src/test/ui/rmeta-rpass.rs +++ b/src/test/ui/rmeta-rpass.rs @@ -1,6 +1,11 @@ // run-pass // Test that using rlibs and rmeta dep crates work together. Specifically, that -// there can be both an rmeta and an rlib file and rustc will prefer the rlib. +// there can be both an rmeta and an rlib file and rustc will prefer the rmeta +// file. +// +// This behavior is simply making sure this doesn't accidentally change; in this +// case we want to make sure that the rlib isn't being used as that would cause +// bugs in -Zbinary-dep-depinfo (see #68298). // aux-build:rmeta-rmeta.rs // aux-build:rmeta-rlib-rpass.rs @@ -9,5 +14,5 @@ extern crate rmeta_aux; use rmeta_aux::Foo; pub fn main() { - let _ = Foo { field: 42 }; + let _ = Foo { field2: 42 }; } |