Auto merge of #76588 - guswynn:debug_logging, r=jyn514,Mark-Simulacrum

Add a dedicated debug-logging option to config.toml

`@Mark-Simulacrum` and I were talking in zulip and we found that turning on debug/trace logging in rustc is fairly confusing, as it effectively depends on debug-assertions and is not documented as such. `@Mark-Simulacrum` mentioned that we should probably have a separate option for logging anyways.

this diff adds that, having the option follow debug-assertions (so everyone's existing config.toml should be fine) and if the option is false

to test I ran ./x.py test <something> twice, once with `debug-logging = false` and once with `debug-logging = true` and made sure i only saw trace's when it was true

5 files changed, 27 insertions, 3 deletions

diff --git a/compiler/rustc/Cargo.toml b/compiler/rustc/Cargo.toml
index cf011e63e02..6e6c0c71a1f 100644
--- a/compiler/rustc/Cargo.toml
+++ b/compiler/rustc/Cargo.toml
@@ -19,3 +19,4 @@ features = ['unprefixed_malloc_on_supported_platforms']
 [features]
 jemalloc = ['jemalloc-sys']
 llvm = ['rustc_driver/llvm']
+max_level_info = ['rustc_driver/max_level_info']
diff --git a/compiler/rustc_driver/Cargo.toml b/compiler/rustc_driver/Cargo.toml
index 0d9dcb262b2..adfce1008e1 100644
--- a/compiler/rustc_driver/Cargo.toml
+++ b/compiler/rustc_driver/Cargo.toml
@@ -9,7 +9,7 @@ crate-type = ["dylib"]
 
 [dependencies]
 libc = "0.2"
-tracing = { version = "0.1.18", features = ["release_max_level_info"]  }
+tracing = { version = "0.1.18" }
 tracing-subscriber = { version = "0.2.10", default-features = false, features = ["fmt", "env-filter", "smallvec", "parking_lot", "ansi"] }
 rustc_middle = { path = "../rustc_middle" }
 rustc_ast_pretty = { path = "../rustc_ast_pretty" }
@@ -38,3 +38,4 @@ winapi = { version = "0.3", features = ["consoleapi", "debugapi", "processenv"]
 
 [features]
 llvm = ['rustc_interface/llvm']
+max_level_info = ['tracing/max_level_info']
diff --git a/config.toml.example b/config.toml.example
index b50406a9579..39c94d41e3a 100644
--- a/config.toml.example
+++ b/config.toml.example
@@ -337,13 +337,19 @@
 # binary, otherwise they are omitted.
 #
 # Defaults to rust.debug value
-#debug-assertions = false
+#debug-assertions = debug
 
 # Whether or not debug assertions are enabled for the standard library.
 # Overrides the `debug-assertions` option, if defined.
 #
 # Defaults to rust.debug-assertions value
-#debug-assertions-std = false
+#debug-assertions-std = debug-assertions
+
+# Whether or not to leave debug! and trace! calls in the rust binary.
+# Overrides the `debug-assertions` option, if defined.
+# 
+# Defaults to rust.debug-assertions value
+#debug-logging = debug-assertions
 
 # Debuginfo level for most of Rust code, corresponds to the `-C debuginfo=N` option of `rustc`.
 # `0` - no debug info
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 000f8cef614..7c8c729b5bf 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -112,6 +112,7 @@ pub struct Config {
     pub rust_codegen_units_std: Option<u32>,
     pub rust_debug_assertions: bool,
     pub rust_debug_assertions_std: bool,
+    pub rust_debug_logging: bool,
     pub rust_debuginfo_level_rustc: u32,
     pub rust_debuginfo_level_std: u32,
     pub rust_debuginfo_level_tools: u32,
@@ -392,6 +393,7 @@ struct Rust {
     codegen_units_std: Option<u32>,
     debug_assertions: Option<bool>,
     debug_assertions_std: Option<bool>,
+    debug_logging: Option<bool>,
     debuginfo_level: Option<u32>,
     debuginfo_level_rustc: Option<u32>,
     debuginfo_level_std: Option<u32>,
@@ -600,6 +602,7 @@ impl Config {
         let mut debug = None;
         let mut debug_assertions = None;
         let mut debug_assertions_std = None;
+        let mut debug_logging = None;
         let mut debuginfo_level = None;
         let mut debuginfo_level_rustc = None;
         let mut debuginfo_level_std = None;
@@ -680,6 +683,7 @@ impl Config {
             debug = rust.debug;
             debug_assertions = rust.debug_assertions;
             debug_assertions_std = rust.debug_assertions_std;
+            debug_logging = rust.debug_logging;
             debuginfo_level = rust.debuginfo_level;
             debuginfo_level_rustc = rust.debuginfo_level_rustc;
             debuginfo_level_std = rust.debuginfo_level_std;
@@ -797,6 +801,8 @@ impl Config {
         config.rust_debug_assertions_std =
             debug_assertions_std.unwrap_or(config.rust_debug_assertions);
 
+        config.rust_debug_logging = debug_logging.unwrap_or(config.rust_debug_assertions);
+
         let with_defaults = |debuginfo_level_specific: Option<u32>| {
             debuginfo_level_specific.or(debuginfo_level).unwrap_or(if debug == Some(true) {
                 1
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 170c93561ef..91b85f5af1d 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -541,6 +541,16 @@ impl Build {
         if self.config.llvm_enabled() {
             features.push_str(" llvm");
         }
+
+        // If debug logging is on, then we want the default for tracing:
+        // https://github.com/tokio-rs/tracing/blob/3dd5c03d907afdf2c39444a29931833335171554/tracing/src/level_filters.rs#L26
+        // which is everything (including debug/trace/etc.)
+        // if its unset, if debug_assertions is on, then debug_logging will also be on
+        // as well as tracing *ignoring* this feature when debug_assertions is on
+        if !self.config.rust_debug_logging {
+            features.push_str(" max_level_info");
+        }
+
         features
     }