perf(compile)!: Switch dev profile to debug=lines-and-tables-only

With #17215 merged, users can set the new `debug` profile as their
default build profile without an MSRV bump and get the same behavior
between previous versions of Cargo and those that include this change.

There is still the possibility of `opt-level` but that is less certain.

For cargo `cargo test --no-run` build+target dir:
- master:  3.6G
- this PR: 2.9G

For bevy `cargo test --no-run` build+target dir:
- master:  369G
- this PR: 348G

Surprised at how much space was taken up:
- `build/`: 189G -> 174G
- `examples/`: 175G -> 168G (across 364 examples)
- `incremental/`: 14G -> 8G

Fixes #15931

Author: epage

doc/book/src/reference/profiles.md

@@ -422,7 +422,7 @@ The default settings for the `dev` profile are:
 ```toml
 [profile.dev]
 opt-level = 0
-debug = true
+debug = "line-tables-only"
 split-debuginfo = '...'  # Platform-specific.
 strip = "none"
 debug-assertions = true
@@ -444,6 +444,7 @@ The default settings for the `debug` profile are:
 ```toml
 [profile.debug]
 inherits = "dev"
+debug = true
 ```
 
 ### release

src/workspace/profiles.rs

@@ -157,6 +157,7 @@ impl Profiles {
                 "debug",
                 TomlProfile {
                     inherits: Some(String::from("dev")),
+                    debug: Some(TomlDebugInfo::Full),
                     ..TomlProfile::default()
                 },
             ),
@@ -774,7 +775,7 @@ impl Profile {
         Profile {
             name: "dev".into(),
             root: ProfileRoot::Debug,
-            debuginfo: DebugInfo::Resolved(TomlDebugInfo::Full),
+            debuginfo: DebugInfo::Resolved(TomlDebugInfo::LineTablesOnly),
             debug_assertions: true,
             overflow_checks: true,
             incremental: true,

tests/testsuite/build.rs

@@ -5339,9 +5339,9 @@ fn build_filter_infer_profile() {
     p.cargo("build -v --test=t1")
         .with_stderr_data(str![[r#"
 [COMPILING] foo v0.0.1 ([ROOT]/foo)
-[RUNNING] `rustc --crate-name foo --edition=2015 src/lib.rs [..]--crate-type lib --emit=[..]link[..] -C debuginfo=2 [..]`
-[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--crate-type bin --emit=[..]link[..] -C debuginfo=2 [..]`
-[RUNNING] `rustc --crate-name t1 --edition=2015 tests/t1.rs [..]--emit=[..]link[..] -C debuginfo=2 [..]`
+[RUNNING] `rustc --crate-name foo --edition=2015 src/lib.rs [..]--crate-type lib --emit=[..]link[..] -C debuginfo=line-tables-only [..]`
+[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--crate-type bin --emit=[..]link[..] -C debuginfo=line-tables-only [..]`
+[RUNNING] `rustc --crate-name t1 --edition=2015 tests/t1.rs [..]--emit=[..]link[..] -C debuginfo=line-tables-only [..]`
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]].unordered())
@@ -5352,9 +5352,9 @@ fn build_filter_infer_profile() {
     p.cargo("build -v --bench=b1")
         .with_stderr_data(str![[r#"
 [COMPILING] foo v0.0.1 ([ROOT]/foo)
-[RUNNING] `rustc --crate-name foo --edition=2015 src/lib.rs [..]--crate-type lib --emit=[..]link [..]-C debuginfo=2 [..]`
-[RUNNING] `rustc --crate-name b1 --edition=2015 benches/b1.rs [..]--emit=[..]link[..] -C embed-bitcode=no -C debuginfo=2 [..]--test [..]`
-[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--crate-type bin --emit=[..]link [..]-C debuginfo=2 [..]`
+[RUNNING] `rustc --crate-name foo --edition=2015 src/lib.rs [..]--crate-type lib --emit=[..]link [..]-C debuginfo=line-tables-only [..]`
+[RUNNING] `rustc --crate-name b1 --edition=2015 benches/b1.rs [..]--emit=[..]link[..] -C embed-bitcode=no -C debuginfo=line-tables-only [..]--test [..]`
+[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--crate-type bin --emit=[..]link [..]-C debuginfo=line-tables-only [..]`
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]].unordered())
@@ -5391,7 +5391,7 @@ fn targets_selected_all() {
     p.cargo("build -v --all-targets")
         .with_stderr_data(str![[r#"
 [COMPILING] foo v0.0.1 ([ROOT]/foo)
-[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--emit=[..]link [..]-C debuginfo=2 -[..]-test[..]`
+[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--emit=[..]link [..]-C debuginfo=line-tables-only -[..]-test[..]`
 [RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--crate-type bin --emit=[..]link[..]`
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
@@ -5407,7 +5407,7 @@ fn all_targets_no_lib() {
     p.cargo("build -v --all-targets")
         .with_stderr_data(str![[r#"
 [COMPILING] foo v0.0.1 ([ROOT]/foo)
-[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--emit=[..]link[..] -C debuginfo=2 [..]--test [..]`
+[RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--emit=[..]link[..] -C debuginfo=line-tables-only [..]--test [..]`
 [RUNNING] `rustc --crate-name foo --edition=2015 src/main.rs [..]--crate-type bin --emit=[..]link[..]`
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 

tests/testsuite/build_script.rs

@@ -2817,7 +2817,7 @@ fn build_cmd_with_a_build_cmd() {
 [COMPILING] foo v0.5.0 ([ROOT]/foo)
 [RUNNING] `rustc --crate-name build_script_build --edition=2015 build.rs [..]--crate-type bin --emit=[..]link[..]-C metadata=[..]`
 [RUNNING] `[ROOT]/foo/target/debug/build/foo/[HASH]/out/build_script_build`
-[RUNNING] `rustc --crate-name foo [..]src/lib.rs [..]--crate-type lib --emit=[..]-C debuginfo=2 [..]-C metadata=[..]`
+[RUNNING] `rustc --crate-name foo [..]src/lib.rs [..]--crate-type lib --emit=[..]-C debuginfo=line-tables-only [..]-C metadata=[..]`
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]]).run();

tests/testsuite/features2.rs

@@ -1170,7 +1170,7 @@ fn proc_macro_ws() {
             resolver = "2"
 
             [profile.dev.build-override]
-            debug = true
+            debug = "line-tables-only"
             "#,
         )
         .file(

tests/testsuite/profile_custom.rs

@@ -795,7 +795,7 @@ fn debug_inherits_dev() {
         .with_stderr_data(str![[r#"
 [CHECKING] foo v0.1.0 ([ROOT]/foo)
 [RUNNING] `rustc --crate-name foo [..]`
-[FINISHED] `debug` profile [optimized] target(s) in [ELAPSED]s
+[FINISHED] `debug` profile [optimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
         .with_stderr_does_not_contain("[..] -C debuginfo=0[..]")

tests/testsuite/profile_settings.rs

@@ -56,7 +56,7 @@ fn opt_level_override_0() {
         .build();
     p.cargo("build -v").with_stderr_data(str![[r#"
 [COMPILING] test v0.0.0 ([ROOT]/foo)
-[RUNNING] `rustc --crate-name test --edition=2015 src/lib.rs [..]--crate-type lib --emit=[..]link[..]-C debuginfo=2 [..] -C metadata=[..] --out-dir [..]`
+[RUNNING] `rustc --crate-name test --edition=2015 src/lib.rs [..]--crate-type lib --emit=[..]link[..]-C debuginfo=line-tables-only [..] -C metadata=[..] --out-dir [..]`
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]]).run();
@@ -116,7 +116,7 @@ fn check_opt_level_override(profile_level: &str, rustc_level: &str) {
 [RUNNING] `rustc --crate-name test --edition=2015 src/lib.rs [..]--crate-type lib \
         --emit=[..]link[..] \
         -C opt-level={level}[..]\
-        -C debuginfo=2 [..]\
+        -C debuginfo=line-tables-only [..]\
         -C debug-assertions=on[..] \
         -C metadata=[..] \
         --out-dir [..]`