From ec7230fea2f4a96a1993c54bf2b17892d2e978b4 Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Fri, 24 Jul 2020 20:42:00 +0200
Subject: [PATCH 1/7] Move from `log` to `tracing`

---
 Cargo.lock                                 | 168 +++++++++++++++------
 src/librustc_ast/Cargo.toml                |   2 +-
 src/librustc_ast_lowering/Cargo.toml       |   2 +-
 src/librustc_ast_passes/Cargo.toml         |   2 +-
 src/librustc_ast_pretty/Cargo.toml         |   2 +-
 src/librustc_builtin_macros/Cargo.toml     |   2 +-
 src/librustc_codegen_llvm/Cargo.toml       |   2 +-
 src/librustc_codegen_ssa/Cargo.toml        |   2 +-
 src/librustc_data_structures/Cargo.toml    |   2 +-
 src/librustc_driver/Cargo.toml             |   4 +-
 src/librustc_driver/lib.rs                 |   6 +-
 src/librustc_errors/Cargo.toml             |   2 +-
 src/librustc_expand/Cargo.toml             |   2 +-
 src/librustc_hir/Cargo.toml                |   2 +-
 src/librustc_incremental/Cargo.toml        |   2 +-
 src/librustc_infer/Cargo.toml              |   2 +-
 src/librustc_interface/Cargo.toml          |   2 +-
 src/librustc_lint/Cargo.toml               |   2 +-
 src/librustc_metadata/Cargo.toml           |   2 +-
 src/librustc_middle/Cargo.toml             |   2 +-
 src/librustc_mir/Cargo.toml                |   2 +-
 src/librustc_mir/interpret/eval_context.rs |   3 +-
 src/librustc_mir_build/Cargo.toml          |   2 +-
 src/librustc_parse/Cargo.toml              |   2 +-
 src/librustc_passes/Cargo.toml             |   2 +-
 src/librustc_privacy/Cargo.toml            |   2 +-
 src/librustc_query_system/Cargo.toml       |   2 +-
 src/librustc_resolve/Cargo.toml            |   2 +-
 src/librustc_save_analysis/Cargo.toml      |   2 +-
 src/librustc_session/Cargo.toml            |   2 +-
 src/librustc_span/Cargo.toml               |   2 +-
 src/librustc_symbol_mangling/Cargo.toml    |   2 +-
 src/librustc_target/Cargo.toml             |   2 +-
 src/librustc_trait_selection/Cargo.toml    |   2 +-
 src/librustc_traits/Cargo.toml             |   2 +-
 src/librustc_ty/Cargo.toml                 |   2 +-
 src/librustc_typeck/Cargo.toml             |   2 +-
 src/tools/compiletest/Cargo.toml           |   2 +-
 38 files changed, 165 insertions(+), 84 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index f6f2468055a1..367bf2ff0d92 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -61,7 +61,7 @@ version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c7021ce4924a3f25f802b2cccd1af585e39ea1a363a1aa2e72afe54b67a3a7a7"
 dependencies = [
- "ansi_term",
+ "ansi_term 0.11.0",
 ]
 
 [[package]]
@@ -79,6 +79,15 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "ansi_term"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d52a9bb7ec0cf484c551830a7ce27bd20d67eac647e1befb56b0be4ee39a55d2"
+dependencies = [
+ "winapi 0.3.8",
+]
+
 [[package]]
 name = "anyhow"
 version = "1.0.31"
@@ -496,7 +505,7 @@ version = "2.33.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5067f5bb2d80ef5d68b4c87db81601f0b75bca627bc2ef76b141d7b846a3c6d9"
 dependencies = [
- "ansi_term",
+ "ansi_term 0.11.0",
  "atty",
  "bitflags",
  "strsim",
@@ -616,12 +625,12 @@ dependencies = [
  "glob",
  "lazy_static",
  "libc",
- "log",
  "miow 0.3.3",
  "regex",
  "rustfix",
  "serde",
  "serde_json",
+ "tracing",
  "walkdir",
  "winapi 0.3.8",
 ]
@@ -1741,6 +1750,15 @@ dependencies = [
  "tendril",
 ]
 
+[[package]]
+name = "matchers"
+version = "0.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f099785f7595cc4b4553a174ce30dd7589ef93391ff414dbb67f62392b9e0ce1"
+dependencies = [
+ "regex-automata",
+]
+
 [[package]]
 name = "matches"
 version = "0.1.8"
@@ -2314,7 +2332,7 @@ version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f81e1644e1b54f5a68959a29aa86cde704219254669da328ecfdf6a1f09d427"
 dependencies = [
- "ansi_term",
+ "ansi_term 0.11.0",
  "ctor",
  "difference",
  "output_vt100",
@@ -2678,6 +2696,16 @@ dependencies = [
  "thread_local",
 ]
 
+[[package]]
+name = "regex-automata"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae1ded71d66a4a97f5e961fd0cb25a5f366a42a41570d16a763a69c092c26ae4"
+dependencies = [
+ "byteorder",
+ "regex-syntax",
+]
+
 [[package]]
 name = "regex-syntax"
 version = "0.6.17"
@@ -3228,7 +3256,6 @@ name = "rustc_ast"
 version = "0.0.0"
 dependencies = [
  "bitflags",
- "log",
  "rustc_data_structures",
  "rustc_index",
  "rustc_lexer",
@@ -3237,13 +3264,13 @@ dependencies = [
  "rustc_span",
  "scoped-tls",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
 name = "rustc_ast_lowering"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_arena",
  "rustc_ast",
  "rustc_ast_pretty",
@@ -3255,6 +3282,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3262,7 +3290,6 @@ name = "rustc_ast_passes"
 version = "0.0.0"
 dependencies = [
  "itertools 0.8.0",
- "log",
  "rustc_ast",
  "rustc_ast_pretty",
  "rustc_attr",
@@ -3272,16 +3299,17 @@ dependencies = [
  "rustc_parse",
  "rustc_session",
  "rustc_span",
+ "tracing",
 ]
 
 [[package]]
 name = "rustc_ast_pretty"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_ast",
  "rustc_span",
  "rustc_target",
+ "tracing",
 ]
 
 [[package]]
@@ -3304,7 +3332,6 @@ dependencies = [
 name = "rustc_builtin_macros"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_ast",
  "rustc_ast_pretty",
  "rustc_attr",
@@ -3318,6 +3345,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3327,7 +3355,6 @@ dependencies = [
  "bitflags",
  "flate2",
  "libc",
- "log",
  "measureme",
  "rustc-demangle",
  "rustc_ast",
@@ -3347,6 +3374,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3357,7 +3385,6 @@ dependencies = [
  "cc",
  "jobserver",
  "libc",
- "log",
  "memmap",
  "num_cpus",
  "pathdiff",
@@ -3377,6 +3404,7 @@ dependencies = [
  "rustc_symbol_mangling",
  "rustc_target",
  "tempfile",
+ "tracing",
 ]
 
 [[package]]
@@ -3391,7 +3419,6 @@ dependencies = [
  "jobserver",
  "lazy_static",
  "libc",
- "log",
  "measureme",
  "once_cell",
  "parking_lot 0.10.2",
@@ -3404,6 +3431,7 @@ dependencies = [
  "smallvec 1.4.0",
  "stable_deref_trait",
  "stacker",
+ "tracing",
  "winapi 0.3.8",
 ]
 
@@ -3411,10 +3439,8 @@ dependencies = [
 name = "rustc_driver"
 version = "0.0.0"
 dependencies = [
- "env_logger 0.7.1",
  "lazy_static",
  "libc",
- "log",
  "rustc_ast",
  "rustc_ast_pretty",
  "rustc_codegen_ssa",
@@ -3436,6 +3462,8 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "rustc_target",
+ "tracing",
+ "tracing-subscriber",
  "winapi 0.3.8",
 ]
 
@@ -3449,12 +3477,12 @@ version = "0.0.0"
 dependencies = [
  "annotate-snippets 0.8.0",
  "atty",
- "log",
  "rustc_data_structures",
  "rustc_serialize",
  "rustc_span",
  "termcolor",
  "termize",
+ "tracing",
  "unicode-width",
  "winapi 0.3.8",
 ]
@@ -3463,7 +3491,6 @@ dependencies = [
 name = "rustc_expand"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_ast",
  "rustc_ast_passes",
  "rustc_ast_pretty",
@@ -3477,6 +3504,7 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3501,7 +3529,6 @@ name = "rustc_hir"
 version = "0.0.0"
 dependencies = [
  "lazy_static",
- "log",
  "rustc_ast",
  "rustc_data_structures",
  "rustc_index",
@@ -3510,6 +3537,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3527,7 +3555,6 @@ dependencies = [
 name = "rustc_incremental"
 version = "0.0.0"
 dependencies = [
- "log",
  "rand 0.7.3",
  "rustc_ast",
  "rustc_data_structures",
@@ -3538,6 +3565,7 @@ dependencies = [
  "rustc_serialize",
  "rustc_session",
  "rustc_span",
+ "tracing",
 ]
 
 [[package]]
@@ -3552,7 +3580,6 @@ dependencies = [
 name = "rustc_infer"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_ast",
  "rustc_data_structures",
  "rustc_errors",
@@ -3566,6 +3593,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3573,7 +3601,6 @@ name = "rustc_interface"
 version = "0.0.0"
 dependencies = [
  "libc",
- "log",
  "once_cell",
  "rustc-rayon",
  "rustc_ast",
@@ -3609,6 +3636,7 @@ dependencies = [
  "rustc_typeck",
  "smallvec 1.4.0",
  "tempfile",
+ "tracing",
  "winapi 0.3.8",
 ]
 
@@ -3623,7 +3651,6 @@ dependencies = [
 name = "rustc_lint"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_ast",
  "rustc_ast_pretty",
  "rustc_attr",
@@ -3637,6 +3664,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "rustc_trait_selection",
+ "tracing",
  "unicode-security",
 ]
 
@@ -3665,7 +3693,6 @@ version = "0.0.0"
 dependencies = [
  "flate2",
  "libc",
- "log",
  "memmap",
  "rustc_ast",
  "rustc_attr",
@@ -3682,6 +3709,7 @@ dependencies = [
  "rustc_target",
  "smallvec 1.4.0",
  "stable_deref_trait",
+ "tracing",
  "winapi 0.3.8",
 ]
 
@@ -3692,7 +3720,6 @@ dependencies = [
  "bitflags",
  "byteorder",
  "chalk-ir",
- "log",
  "measureme",
  "polonius-engine",
  "rustc-rayon-core",
@@ -3713,6 +3740,7 @@ dependencies = [
  "rustc_target",
  "scoped-tls",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3721,7 +3749,6 @@ version = "0.0.0"
 dependencies = [
  "either",
  "itertools 0.8.0",
- "log",
  "log_settings",
  "polonius-engine",
  "rustc_apfloat",
@@ -3742,13 +3769,13 @@ dependencies = [
  "rustc_target",
  "rustc_trait_selection",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
 name = "rustc_mir_build"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_apfloat",
  "rustc_arena",
  "rustc_ast",
@@ -3765,6 +3792,7 @@ dependencies = [
  "rustc_target",
  "rustc_trait_selection",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3772,7 +3800,6 @@ name = "rustc_parse"
 version = "0.0.0"
 dependencies = [
  "bitflags",
- "log",
  "rustc_ast",
  "rustc_ast_pretty",
  "rustc_data_structures",
@@ -3781,6 +3808,7 @@ dependencies = [
  "rustc_lexer",
  "rustc_session",
  "rustc_span",
+ "tracing",
  "unicode-normalization",
 ]
 
@@ -3796,7 +3824,6 @@ dependencies = [
 name = "rustc_passes"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_ast",
  "rustc_attr",
  "rustc_data_structures",
@@ -3808,6 +3835,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "rustc_trait_selection",
+ "tracing",
 ]
 
 [[package]]
@@ -3828,7 +3856,6 @@ dependencies = [
 name = "rustc_privacy"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_attr",
  "rustc_data_structures",
  "rustc_errors",
@@ -3837,13 +3864,13 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "rustc_typeck",
+ "tracing",
 ]
 
 [[package]]
 name = "rustc_query_system"
 version = "0.0.0"
 dependencies = [
- "log",
  "parking_lot 0.10.2",
  "rustc-rayon-core",
  "rustc_arena",
@@ -3853,6 +3880,7 @@ dependencies = [
  "rustc_serialize",
  "rustc_span",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -3860,7 +3888,6 @@ name = "rustc_resolve"
 version = "0.0.0"
 dependencies = [
  "bitflags",
- "log",
  "rustc_arena",
  "rustc_ast",
  "rustc_ast_lowering",
@@ -3877,13 +3904,13 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
 name = "rustc_save_analysis"
 version = "0.0.0"
 dependencies = [
- "log",
  "rls-data",
  "rls-span",
  "rustc_ast",
@@ -3896,6 +3923,7 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "serde_json",
+ "tracing",
 ]
 
 [[package]]
@@ -3912,7 +3940,6 @@ version = "0.0.0"
 dependencies = [
  "bitflags",
  "getopts",
- "log",
  "num_cpus",
  "rustc_ast",
  "rustc_data_structures",
@@ -3922,6 +3949,7 @@ dependencies = [
  "rustc_serialize",
  "rustc_span",
  "rustc_target",
+ "tracing",
 ]
 
 [[package]]
@@ -3929,7 +3957,6 @@ name = "rustc_span"
 version = "0.0.0"
 dependencies = [
  "cfg-if",
- "log",
  "md-5",
  "rustc_arena",
  "rustc_data_structures",
@@ -3938,6 +3965,7 @@ dependencies = [
  "rustc_serialize",
  "scoped-tls",
  "sha-1",
+ "tracing",
  "unicode-width",
 ]
 
@@ -3945,7 +3973,6 @@ dependencies = [
 name = "rustc_symbol_mangling"
 version = "0.0.0"
 dependencies = [
- "log",
  "punycode",
  "rustc-demangle",
  "rustc_ast",
@@ -3955,6 +3982,7 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "rustc_target",
+ "tracing",
 ]
 
 [[package]]
@@ -3962,12 +3990,12 @@ name = "rustc_target"
 version = "0.0.0"
 dependencies = [
  "bitflags",
- "log",
  "rustc_data_structures",
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
  "rustc_span",
+ "tracing",
 ]
 
 [[package]]
@@ -3984,7 +4012,6 @@ checksum = "b725dadae9fabc488df69a287f5a99c5eaf5d10853842a8a3dfac52476f544ee"
 name = "rustc_trait_selection"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_ast",
  "rustc_attr",
  "rustc_data_structures",
@@ -3999,6 +4026,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -4007,7 +4035,6 @@ version = "0.0.0"
 dependencies = [
  "chalk-ir",
  "chalk-solve",
- "log",
  "rustc_ast",
  "rustc_data_structures",
  "rustc_hir",
@@ -4017,13 +4044,13 @@ dependencies = [
  "rustc_span",
  "rustc_trait_selection",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
 name = "rustc_ty"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_data_structures",
  "rustc_errors",
  "rustc_hir",
@@ -4033,13 +4060,13 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "rustc_trait_selection",
+ "tracing",
 ]
 
 [[package]]
 name = "rustc_typeck"
 version = "0.0.0"
 dependencies = [
- "log",
  "rustc_arena",
  "rustc_ast",
  "rustc_attr",
@@ -4055,6 +4082,7 @@ dependencies = [
  "rustc_target",
  "rustc_trait_selection",
  "smallvec 1.4.0",
+ "tracing",
 ]
 
 [[package]]
@@ -4284,6 +4312,15 @@ dependencies = [
  "opaque-debug",
 ]
 
+[[package]]
+name = "sharded-slab"
+version = "0.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06d5a3f5166fb5b42a5439f2eee8b9de149e235961e3eb21c5808fc3ea17ff3e"
+dependencies = [
+ "lazy_static",
+]
+
 [[package]]
 name = "shell-escape"
 version = "0.1.4"
@@ -4931,9 +4968,9 @@ dependencies = [
 
 [[package]]
 name = "tracing"
-version = "0.1.15"
+version = "0.1.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a41f40ed0e162c911ac6fcb53ecdc8134c46905fdbbae8c50add462a538b495f"
+checksum = "f0aae59226cf195d8e74d4b34beae1859257efb4e5fed3f147d2dc2c7d372178"
 dependencies = [
  "cfg-if",
  "tracing-attributes",
@@ -4942,9 +4979,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-attributes"
-version = "0.1.8"
+version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99bbad0de3fd923c9c3232ead88510b783e5a4d16a6154adffa3d53308de984c"
+checksum = "f0693bf8d6f2bf22c690fc61a9d21ac69efdbb894a17ed596b9af0f01e64b84b"
 dependencies = [
  "proc-macro2 1.0.3",
  "quote 1.0.2",
@@ -4953,13 +4990,54 @@ dependencies = [
 
 [[package]]
 name = "tracing-core"
-version = "0.1.10"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0aa83a9a47081cd522c09c81b31aec2c9273424976f922ad61c053b58350b715"
+checksum = "b2734b5a028fa697686f16c6d18c2c6a3c7e41513f9a213abb6754c4acb3c8d7"
 dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "tracing-log"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e0f8c7178e13481ff6765bd169b33e8d554c5d2bbede5e32c356194be02b9b9"
+dependencies = [
+ "lazy_static",
+ "log",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-serde"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6ccba2f8f16e0ed268fc765d9b7ff22e965e7185d32f8f1ec8294fe17d86e79"
+dependencies = [
+ "serde",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.2.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7b33f8b2ef2ab0c3778c12646d9c42a24f7772bee4cdafc72199644a9f58fdc"
+dependencies = [
+ "ansi_term 0.12.1",
+ "chrono",
+ "lazy_static",
+ "matchers",
+ "regex",
+ "serde",
+ "serde_json",
+ "sharded-slab",
+ "smallvec 1.4.0",
+ "tracing-core",
+ "tracing-log",
+ "tracing-serde",
+]
+
 [[package]]
 name = "typenum"
 version = "1.12.0"
diff --git a/src/librustc_ast/Cargo.toml b/src/librustc_ast/Cargo.toml
index 6bd65fd5f96c..a36f49bd4146 100644
--- a/src/librustc_ast/Cargo.toml
+++ b/src/librustc_ast/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_serialize = { path = "../librustc_serialize" }
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 scoped-tls = "1.0"
 rustc_span = { path = "../librustc_span" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_ast_lowering/Cargo.toml b/src/librustc_ast_lowering/Cargo.toml
index d71eb4fcd5c2..51f34a1b78e9 100644
--- a/src/librustc_ast_lowering/Cargo.toml
+++ b/src/librustc_ast_lowering/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_arena = { path = "../librustc_arena" }
-log = { version = "0.4", features = ["release_max_level_info", "std"] }
+log = { package = "tracing", version = "0.1" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_hir = { path = "../librustc_hir" }
 rustc_target = { path = "../librustc_target" }
diff --git a/src/librustc_ast_passes/Cargo.toml b/src/librustc_ast_passes/Cargo.toml
index e4d1d79abb2d..c53089a4afc5 100644
--- a/src/librustc_ast_passes/Cargo.toml
+++ b/src/librustc_ast_passes/Cargo.toml
@@ -10,7 +10,7 @@ path = "lib.rs"
 
 [dependencies]
 itertools = "0.8"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_attr = { path = "../librustc_attr" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_ast_pretty/Cargo.toml b/src/librustc_ast_pretty/Cargo.toml
index 6c076d2c5b86..4035346d3544 100644
--- a/src/librustc_ast_pretty/Cargo.toml
+++ b/src/librustc_ast_pretty/Cargo.toml
@@ -10,7 +10,7 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_span = { path = "../librustc_span" }
 rustc_ast = { path = "../librustc_ast" }
 rustc_target = { path = "../librustc_target" }
diff --git a/src/librustc_builtin_macros/Cargo.toml b/src/librustc_builtin_macros/Cargo.toml
index fdb6c359052d..c612781153e8 100644
--- a/src/librustc_builtin_macros/Cargo.toml
+++ b/src/librustc_builtin_macros/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_parse_format = { path = "../librustc_parse_format" }
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_attr = { path = "../librustc_attr" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_codegen_llvm/Cargo.toml b/src/librustc_codegen_llvm/Cargo.toml
index bedefcc30ed8..ec4dfabdcc2f 100644
--- a/src/librustc_codegen_llvm/Cargo.toml
+++ b/src/librustc_codegen_llvm/Cargo.toml
@@ -15,7 +15,7 @@ bitflags = "1.0"
 flate2 = "1.0"
 libc = "0.2"
 measureme = "0.7.1"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc-demangle = "0.1"
 rustc_attr = { path = "../librustc_attr" }
diff --git a/src/librustc_codegen_ssa/Cargo.toml b/src/librustc_codegen_ssa/Cargo.toml
index e100e0095c92..8fa0de37648f 100644
--- a/src/librustc_codegen_ssa/Cargo.toml
+++ b/src/librustc_codegen_ssa/Cargo.toml
@@ -14,7 +14,7 @@ bitflags = "1.2.1"
 cc = "1.0.1"
 num_cpus = "1.0"
 memmap = "0.7"
-log = "0.4.5"
+log = { package = "tracing", version = "0.1" }
 libc = "0.2.50"
 jobserver = "0.1.11"
 tempfile = "3.1"
diff --git a/src/librustc_data_structures/Cargo.toml b/src/librustc_data_structures/Cargo.toml
index 1c2fb90b2d8b..811d1e49626c 100644
--- a/src/librustc_data_structures/Cargo.toml
+++ b/src/librustc_data_structures/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 [dependencies]
 ena = "0.14"
 indexmap = "1"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 jobserver_crate = { version = "0.1.13", package = "jobserver" }
 lazy_static = "1"
 once_cell = { version = "1", features = ["parking_lot"] }
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index 75d659207665..69dd221ef969 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -12,8 +12,8 @@ crate-type = ["dylib"]
 [dependencies]
 lazy_static = "1.0"
 libc = "0.2"
-log = "0.4"
-env_logger = { version = "0.7", default-features = false }
+log = { package = "tracing", version = "0.1.18", features = ["release_max_level_info"]  }
+tracing-subscriber = { version = "0.2.10", features = ["fmt", "env-filter"] }
 rustc_middle = { path = "../librustc_middle" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_target = { path = "../librustc_target" }
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index ab4eac9440b4..6faffae305d1 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -1226,7 +1226,11 @@ pub fn install_ice_hook() {
 /// This allows tools to enable rust logging without having to magically match rustc's
 /// log crate version
 pub fn init_rustc_env_logger() {
-    env_logger::init_from_env("RUSTC_LOG");
+    let builder = tracing_subscriber::FmtSubscriber::builder();
+
+    let builder = builder.with_env_filter(tracing_subscriber::EnvFilter::from_env("RUSTC_LOG"));
+
+    builder.init()
 }
 
 pub fn main() -> ! {
diff --git a/src/librustc_errors/Cargo.toml b/src/librustc_errors/Cargo.toml
index 7f72161aff82..d0f04c3fe764 100644
--- a/src/librustc_errors/Cargo.toml
+++ b/src/librustc_errors/Cargo.toml
@@ -10,7 +10,7 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_serialize = { path = "../librustc_serialize" }
 rustc_span = { path = "../librustc_span" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_expand/Cargo.toml b/src/librustc_expand/Cargo.toml
index ef617acfe131..bdf039c36abf 100644
--- a/src/librustc_expand/Cargo.toml
+++ b/src/librustc_expand/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 
 [dependencies]
 rustc_serialize = { path = "../librustc_serialize" }
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_span = { path = "../librustc_span" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_ast_passes = { path = "../librustc_ast_passes" }
diff --git a/src/librustc_hir/Cargo.toml b/src/librustc_hir/Cargo.toml
index 1b91d769c704..4a404e176e14 100644
--- a/src/librustc_hir/Cargo.toml
+++ b/src/librustc_hir/Cargo.toml
@@ -18,5 +18,5 @@ rustc_span = { path = "../librustc_span" }
 rustc_serialize = { path = "../librustc_serialize" }
 rustc_ast = { path = "../librustc_ast" }
 lazy_static = "1"
-log = { version = "0.4", features = ["release_max_level_info", "std"] }
+log = { package = "tracing", version = "0.1" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_incremental/Cargo.toml b/src/librustc_incremental/Cargo.toml
index 7b3030fa1d9c..60a87078d63c 100644
--- a/src/librustc_incremental/Cargo.toml
+++ b/src/librustc_incremental/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_graphviz = { path = "../librustc_graphviz" }
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rand = "0.7"
 rustc_middle = { path = "../librustc_middle" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_infer/Cargo.toml b/src/librustc_infer/Cargo.toml
index 06fc7ecf95f2..9d56fa223a9c 100644
--- a/src/librustc_infer/Cargo.toml
+++ b/src/librustc_infer/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_graphviz = { path = "../librustc_graphviz" }
-log = { version = "0.4", features = ["release_max_level_info", "std"] }
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_errors = { path = "../librustc_errors" }
diff --git a/src/librustc_interface/Cargo.toml b/src/librustc_interface/Cargo.toml
index 112dc7037f58..5c7edc10dd5c 100644
--- a/src/librustc_interface/Cargo.toml
+++ b/src/librustc_interface/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 libc = "0.2"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rayon = { version = "0.3.0", package = "rustc-rayon" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc_ast = { path = "../librustc_ast" }
diff --git a/src/librustc_lint/Cargo.toml b/src/librustc_lint/Cargo.toml
index 58c15257326a..3ba1566023d2 100644
--- a/src/librustc_lint/Cargo.toml
+++ b/src/librustc_lint/Cargo.toml
@@ -9,7 +9,7 @@ name = "rustc_lint"
 path = "lib.rs"
 
 [dependencies]
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 unicode-security = "0.0.5"
 rustc_middle = { path = "../librustc_middle" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index 7bbe7567d292..2c0e2aa39fd5 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 [dependencies]
 flate2 = "1.0"
 libc = "0.2"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 memmap = "0.7"
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc_middle = { path = "../librustc_middle" }
diff --git a/src/librustc_middle/Cargo.toml b/src/librustc_middle/Cargo.toml
index 02d82c679338..678fcfe65394 100644
--- a/src/librustc_middle/Cargo.toml
+++ b/src/librustc_middle/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 rustc_arena = { path = "../librustc_arena" }
 bitflags = "1.2.1"
 scoped-tls = "1.0"
-log = { version = "0.4", features = ["release_max_level_info", "std"] }
+log = { package = "tracing", version = "0.1" }
 rustc-rayon-core = "0.3.0"
 polonius-engine = "0.12.0"
 rustc_apfloat = { path = "../librustc_apfloat" }
diff --git a/src/librustc_mir/Cargo.toml b/src/librustc_mir/Cargo.toml
index aebce78e4018..f05c47e0ed62 100644
--- a/src/librustc_mir/Cargo.toml
+++ b/src/librustc_mir/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 either = "1.5.0"
 rustc_graphviz = { path = "../librustc_graphviz" }
 itertools = "0.8"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 log_settings = "0.1.1"
 polonius-engine = "0.12.0"
 rustc_middle = { path = "../librustc_middle" }
diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 630b2890835d..879a8e644907 100644
--- a/src/librustc_mir/interpret/eval_context.rs
+++ b/src/librustc_mir/interpret/eval_context.rs
@@ -818,11 +818,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx> {
         // FIXME: should we tell the user that there was a local which was never written to?
         if let LocalValue::Live(Operand::Indirect(MemPlace { ptr, .. })) = local {
-            trace!("deallocating local");
             // All locals have a backing allocation, even if the allocation is empty
             // due to the local having ZST type.
             let ptr = ptr.assert_ptr();
-            trace!("{:?}", self.memory.dump_alloc(ptr.alloc_id));
+            trace!("deallocating local: {:?}", self.memory.dump_alloc(ptr.alloc_id));
             self.memory.deallocate_local(ptr)?;
         };
         Ok(())
diff --git a/src/librustc_mir_build/Cargo.toml b/src/librustc_mir_build/Cargo.toml
index 401a5009e3cf..96059fa43e52 100644
--- a/src/librustc_mir_build/Cargo.toml
+++ b/src/librustc_mir_build/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_arena = { path = "../librustc_arena" }
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_apfloat = { path = "../librustc_apfloat" }
 rustc_attr = { path = "../librustc_attr" }
diff --git a/src/librustc_parse/Cargo.toml b/src/librustc_parse/Cargo.toml
index 7164c6788086..f214ec020cbe 100644
--- a/src/librustc_parse/Cargo.toml
+++ b/src/librustc_parse/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 bitflags = "1.0"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_feature = { path = "../librustc_feature" }
diff --git a/src/librustc_passes/Cargo.toml b/src/librustc_passes/Cargo.toml
index 69048cbf24a3..d9fa435e3ad6 100644
--- a/src/librustc_passes/Cargo.toml
+++ b/src/librustc_passes/Cargo.toml
@@ -9,7 +9,7 @@ name = "rustc_passes"
 path = "lib.rs"
 
 [dependencies]
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_attr = { path = "../librustc_attr" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_privacy/Cargo.toml b/src/librustc_privacy/Cargo.toml
index 6110d2ef7fc9..6f543e71b428 100644
--- a/src/librustc_privacy/Cargo.toml
+++ b/src/librustc_privacy/Cargo.toml
@@ -17,4 +17,4 @@ rustc_typeck = { path = "../librustc_typeck" }
 rustc_session = { path = "../librustc_session" }
 rustc_span = { path = "../librustc_span" }
 rustc_data_structures = { path = "../librustc_data_structures" }
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
diff --git a/src/librustc_query_system/Cargo.toml b/src/librustc_query_system/Cargo.toml
index 73d50f84fe83..64af9c5f1a15 100644
--- a/src/librustc_query_system/Cargo.toml
+++ b/src/librustc_query_system/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_arena = { path = "../librustc_arena" }
-log = { version = "0.4", features = ["release_max_level_info", "std"] }
+log = { package = "tracing", version = "0.1" }
 rustc-rayon-core = "0.3.0"
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_errors = { path = "../librustc_errors" }
diff --git a/src/librustc_resolve/Cargo.toml b/src/librustc_resolve/Cargo.toml
index 6f6104c3d693..1cb49132ead9 100644
--- a/src/librustc_resolve/Cargo.toml
+++ b/src/librustc_resolve/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 
 [dependencies]
 bitflags = "1.2.1"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_ast = { path = "../librustc_ast" }
 rustc_arena = { path = "../librustc_arena" }
 rustc_middle = { path = "../librustc_middle" }
diff --git a/src/librustc_save_analysis/Cargo.toml b/src/librustc_save_analysis/Cargo.toml
index 5948c88054de..7a5ae0ace3ae 100644
--- a/src/librustc_save_analysis/Cargo.toml
+++ b/src/librustc_save_analysis/Cargo.toml
@@ -9,7 +9,7 @@ name = "rustc_save_analysis"
 path = "lib.rs"
 
 [dependencies]
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_ast = { path = "../librustc_ast" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
diff --git a/src/librustc_session/Cargo.toml b/src/librustc_session/Cargo.toml
index abce7359c0ed..35c227df8500 100644
--- a/src/librustc_session/Cargo.toml
+++ b/src/librustc_session/Cargo.toml
@@ -11,7 +11,7 @@ path = "lib.rs"
 [dependencies]
 bitflags = "1.2.1"
 getopts = "0.2"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_errors = { path = "../librustc_errors" }
 rustc_feature = { path = "../librustc_feature" }
 rustc_target = { path = "../librustc_target" }
diff --git a/src/librustc_span/Cargo.toml b/src/librustc_span/Cargo.toml
index 2a7a77487252..2db417ce0e12 100644
--- a/src/librustc_span/Cargo.toml
+++ b/src/librustc_span/Cargo.toml
@@ -18,6 +18,6 @@ rustc_arena = { path = "../librustc_arena" }
 scoped-tls = "1.0"
 unicode-width = "0.1.4"
 cfg-if = "0.1.2"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 sha-1 = "0.8"
 md-5 = "0.8"
diff --git a/src/librustc_symbol_mangling/Cargo.toml b/src/librustc_symbol_mangling/Cargo.toml
index d670ababe9f1..757d86bd95af 100644
--- a/src/librustc_symbol_mangling/Cargo.toml
+++ b/src/librustc_symbol_mangling/Cargo.toml
@@ -10,7 +10,7 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 punycode = "0.4.0"
 rustc-demangle = "0.1.16"
 
diff --git a/src/librustc_target/Cargo.toml b/src/librustc_target/Cargo.toml
index c73490e45132..21796e849856 100644
--- a/src/librustc_target/Cargo.toml
+++ b/src/librustc_target/Cargo.toml
@@ -10,7 +10,7 @@ path = "lib.rs"
 
 [dependencies]
 bitflags = "1.2.1"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_macros = { path = "../librustc_macros" }
 rustc_serialize = { path = "../librustc_serialize" }
diff --git a/src/librustc_trait_selection/Cargo.toml b/src/librustc_trait_selection/Cargo.toml
index fd11a85a9c40..c43fe3f2c0c8 100644
--- a/src/librustc_trait_selection/Cargo.toml
+++ b/src/librustc_trait_selection/Cargo.toml
@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 rustc_parse_format = { path = "../librustc_parse_format" }
-log = { version = "0.4", features = ["release_max_level_info", "std"] }
+log = { package = "tracing", version = "0.1" }
 rustc_attr = { path = "../librustc_attr" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_ast = { path = "../librustc_ast" }
diff --git a/src/librustc_traits/Cargo.toml b/src/librustc_traits/Cargo.toml
index 079b9b10fd09..f8487982e3d4 100644
--- a/src/librustc_traits/Cargo.toml
+++ b/src/librustc_traits/Cargo.toml
@@ -9,7 +9,7 @@ name = "rustc_traits"
 path = "lib.rs"
 
 [dependencies]
-log = { version = "0.4" }
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_hir = { path = "../librustc_hir" }
diff --git a/src/librustc_ty/Cargo.toml b/src/librustc_ty/Cargo.toml
index b6db75e44f97..6cdb35300027 100644
--- a/src/librustc_ty/Cargo.toml
+++ b/src/librustc_ty/Cargo.toml
@@ -9,7 +9,7 @@ name = "rustc_ty"
 path = "lib.rs"
 
 [dependencies]
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_errors = { path = "../librustc_errors" }
diff --git a/src/librustc_typeck/Cargo.toml b/src/librustc_typeck/Cargo.toml
index 93b503c976be..963deda162d6 100644
--- a/src/librustc_typeck/Cargo.toml
+++ b/src/librustc_typeck/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 
 [dependencies]
 rustc_arena = { path = "../librustc_arena" }
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 rustc_middle = { path = "../librustc_middle" }
 rustc_attr = { path = "../librustc_attr" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/tools/compiletest/Cargo.toml b/src/tools/compiletest/Cargo.toml
index 338a167de3fe..bd4c5949800f 100644
--- a/src/tools/compiletest/Cargo.toml
+++ b/src/tools/compiletest/Cargo.toml
@@ -8,7 +8,7 @@ edition = "2018"
 diff = "0.1.10"
 env_logger = { version = "0.7", default-features = false }
 getopts = "0.2"
-log = "0.4"
+log = { package = "tracing", version = "0.1" }
 regex = "1.0"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"

From 64296ec698b1c92ce148b968c101c18e63002bb2 Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Fri, 24 Jul 2020 21:35:14 +0200
Subject: [PATCH 2/7] Add tracing libs to list of permitted dependencies

---
 src/tools/tidy/src/deps.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index e340a0e3f248..55e17466a881 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -166,6 +166,9 @@ const PERMITTED_DEPENDENCIES: &[&str] = &[
     "termcolor",
     "termize",
     "thread_local",
+    "tracing",
+    "tracing-attributes",
+    "tracing-core",
     "typenum",
     "unicode-normalization",
     "unicode-script",

From 208f973d1f8ed7442a64c7784e1b4f5910722eb5 Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Sat, 25 Jul 2020 15:50:51 +0200
Subject: [PATCH 3/7] Make rustdoc share the logger initialization routine with
 rustc.

---
 src/librustc_driver/lib.rs | 11 +++++++++--
 src/librustdoc/lib.rs      |  4 ++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index 6faffae305d1..177fb2c2ec69 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -1224,11 +1224,18 @@ pub fn install_ice_hook() {
 }
 
 /// This allows tools to enable rust logging without having to magically match rustc's
-/// log crate version
+/// log crate version.
 pub fn init_rustc_env_logger() {
+    init_env_logger("RUSTC_LOG")
+}
+
+/// This allows tools to enable rust logging without having to magically match rustc's
+/// log crate version. In contrast to `init_rustc_env_logger` it allows you to choose an env var
+/// other than `RUSTC_LOG`.
+pub fn init_env_logger(env: &str) {
     let builder = tracing_subscriber::FmtSubscriber::builder();
 
-    let builder = builder.with_env_filter(tracing_subscriber::EnvFilter::from_env("RUSTC_LOG"));
+    let builder = builder.with_env_filter(tracing_subscriber::EnvFilter::from_env(env));
 
     builder.init()
 }
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 62780878fd5a..002c5f967105 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -14,7 +14,6 @@
 #![feature(never_type)]
 #![recursion_limit = "256"]
 
-extern crate env_logger;
 #[macro_use]
 extern crate lazy_static;
 extern crate rustc_ast;
@@ -90,7 +89,8 @@ pub fn main() {
     };
     rustc_driver::set_sigpipe_handler();
     rustc_driver::install_ice_hook();
-    env_logger::init_from_env("RUSTDOC_LOG");
+    rustc_driver::init_env_logger("RUSTDOC_LOG");
+
     let res = std::thread::Builder::new()
         .stack_size(thread_stack_size)
         .spawn(move || get_args().map(|args| main_args(&args)).unwrap_or(1))

From 720832c644d4dfe14ec43ae9ef4d74b647ccd77d Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Sat, 25 Jul 2020 17:19:17 +0200
Subject: [PATCH 4/7] Update error index generator to tracing

---
 src/tools/error_index_generator/main.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/tools/error_index_generator/main.rs b/src/tools/error_index_generator/main.rs
index c4292d041d05..bd9f8fb04502 100644
--- a/src/tools/error_index_generator/main.rs
+++ b/src/tools/error_index_generator/main.rs
@@ -1,7 +1,7 @@
 #![feature(rustc_private)]
 
-extern crate env_logger;
 extern crate rustc_ast;
+extern crate rustc_driver;
 extern crate rustc_span;
 
 use std::cell::RefCell;
@@ -282,7 +282,7 @@ fn parse_args() -> (OutputFormat, PathBuf) {
 }
 
 fn main() {
-    env_logger::init();
+    rustc_driver::init_env_logger("RUST_LOG");
     let (format, dst) = parse_args();
     let result = rustc_ast::with_default_session_globals(move || main_with_result(format, &dst));
     if let Err(e) = result {

From 358e21ee781cbcee19ff96b3824b583611e860a5 Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Sun, 26 Jul 2020 13:01:51 +0200
Subject: [PATCH 5/7] Disable log support

---
 Cargo.lock                     | 26 +-------------------------
 src/librustc_driver/Cargo.toml |  2 +-
 2 files changed, 2 insertions(+), 26 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 367bf2ff0d92..46b13db01029 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4997,27 +4997,6 @@ dependencies = [
  "lazy_static",
 ]
 
-[[package]]
-name = "tracing-log"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e0f8c7178e13481ff6765bd169b33e8d554c5d2bbede5e32c356194be02b9b9"
-dependencies = [
- "lazy_static",
- "log",
- "tracing-core",
-]
-
-[[package]]
-name = "tracing-serde"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6ccba2f8f16e0ed268fc765d9b7ff22e965e7185d32f8f1ec8294fe17d86e79"
-dependencies = [
- "serde",
- "tracing-core",
-]
-
 [[package]]
 name = "tracing-subscriber"
 version = "0.2.10"
@@ -5028,14 +5007,11 @@ dependencies = [
  "chrono",
  "lazy_static",
  "matchers",
+ "parking_lot 0.9.0",
  "regex",
- "serde",
- "serde_json",
  "sharded-slab",
  "smallvec 1.4.0",
  "tracing-core",
- "tracing-log",
- "tracing-serde",
 ]
 
 [[package]]
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index 69dd221ef969..2f6c2c6c22c2 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -13,7 +13,7 @@ crate-type = ["dylib"]
 lazy_static = "1.0"
 libc = "0.2"
 log = { package = "tracing", version = "0.1.18", features = ["release_max_level_info"]  }
-tracing-subscriber = { version = "0.2.10", features = ["fmt", "env-filter"] }
+tracing-subscriber = { version = "0.2.10", default-features = false, features = ["fmt", "env-filter", "smallvec", "parking_lot", "ansi", "chrono"] }
 rustc_middle = { path = "../librustc_middle" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_target = { path = "../librustc_target" }

From 401033c68486bc7672cc87e0f4c5b4862e96c778 Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Tue, 28 Jul 2020 15:49:04 +0200
Subject: [PATCH 6/7] Don't register a tracing dispatcher if no tracing env var
 was set.

---
 src/librustc_driver/lib.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index 177fb2c2ec69..7af640c109ed 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -1233,6 +1233,12 @@ pub fn init_rustc_env_logger() {
 /// log crate version. In contrast to `init_rustc_env_logger` it allows you to choose an env var
 /// other than `RUSTC_LOG`.
 pub fn init_env_logger(env: &str) {
+    // Don't register a dispatcher if there's no filter to print anything
+    match std::env::var(env) {
+        Err(_) => return,
+        Ok(s) if s.is_empty() => return,
+        Ok(_) => {}
+    }
     let builder = tracing_subscriber::FmtSubscriber::builder();
 
     let builder = builder.with_env_filter(tracing_subscriber::EnvFilter::from_env(env));

From c7290379be40f930802f0deea87cdb313332e5cc Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Sat, 1 Aug 2020 16:24:52 +0200
Subject: [PATCH 7/7] Remove chrono feature from tracing

---
 Cargo.lock                     | 1 -
 src/librustc_driver/Cargo.toml | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 46b13db01029..7e90b7e6fba1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5004,7 +5004,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f7b33f8b2ef2ab0c3778c12646d9c42a24f7772bee4cdafc72199644a9f58fdc"
 dependencies = [
  "ansi_term 0.12.1",
- "chrono",
  "lazy_static",
  "matchers",
  "parking_lot 0.9.0",
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index 2f6c2c6c22c2..6474a69b216a 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -13,7 +13,7 @@ crate-type = ["dylib"]
 lazy_static = "1.0"
 libc = "0.2"
 log = { package = "tracing", version = "0.1.18", features = ["release_max_level_info"]  }
-tracing-subscriber = { version = "0.2.10", default-features = false, features = ["fmt", "env-filter", "smallvec", "parking_lot", "ansi", "chrono"] }
+tracing-subscriber = { version = "0.2.10", default-features = false, features = ["fmt", "env-filter", "smallvec", "parking_lot", "ansi"] }
 rustc_middle = { path = "../librustc_middle" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }
 rustc_target = { path = "../librustc_target" }