Rollup merge of rust-lang#88269 - prconrad:doctest-persist-binaries, r=jyn514

Doctest persist full binaries when persisting

Tested by adding an extra debug to echo the whole compiler line. Trimmed significantly:

Persisted but not running -> full compile so we get binaries (new behavior).
```
$ rustdoc -Zunstable-options --test --persist-doctests doctests --no-run --extern t=libt.rlib t.rs

DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "doctests/t_rs_8_0/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "-Z" "unstable-options" "--target" "x86_64-unknown-linux-gnu" "--color" "always"
DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "doctests/t_rs_2_0/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "-Z" "unstable-options" "--target" "x86_64-unknown-linux-gnu" "--color" "always"
test t.rs - foople (line 2) - compile ... ok
test t.rs - florp (line 8) - compile ... ok
```

Persisted and running -> full compile.
```
$ rustdoc -Zunstable-options --test --persist-doctests doctests --extern t=libt.rlib t.rs

DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "doctests/t_rs_8_0/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "-Z" "unstable-options" "--target" "x86_64-unknown-linux-gnu" "--color" "always"
DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "doctests/t_rs_2_0/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "-Z" "unstable-options" "--target" "x86_64-unknown-linux-gnu" "--color" "always"

```

Running but not persisted -> full compile only
```
$ rustdoc --test --extern t=libt.rlib t.rs

DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "/tmp/rustdoctestixWAUI/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "--target" "x86_64-unknown-linux-gnu" "--color" "always"
DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "/tmp/rustdoctestKEaJQu/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "--target" "x86_64-unknown-linux-gnu" "--color" "always"

```

Not running and not persisting -> save time and only run metadata.
```
RUSTDOC_LOG=rustdoc=debug,std::test=debug rustdoc -Zunstable-options --no-run --test --extern t=libt.rlib t.rs

DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "/tmp/rustdoctest8twt2c/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "-Z" "unstable-options" "--emit=metadata" "--target" "x86_64-unknown-linux-gnu" "--color" "always"
DEBUG rustdoc::doctest run_test compiler "rustc" "--crate-type" "bin" "--edition" "2015" "-o" "/tmp/rustdoctest3miSqv/rust_out" "--extern" "t=libt.rlib" "-Ccodegen-units=1" "-Z" "unstable-options" "--emit=metadata" "--target" "x86_64-unknown-linux-gnu" "--color" "always"
```

I can't see any infrastructure for automating this sort of test. Am I missing it?

Author: Manishearth

src/librustdoc/doctest.rs

@@ -361,7 +361,7 @@ fn run_test(
     for debugging_option_str in &options.debugging_opts_strs {
         compiler.arg("-Z").arg(&debugging_option_str);
     }
-    if no_run && !compile_fail {
+    if no_run && !compile_fail && options.persist_doctests.is_none() {
         compiler.arg("--emit=metadata");
     }
     compiler.arg("--target").arg(match target {

src/test/run-make/doctests-keep-binaries/Makefile

@@ -0,0 +1,21 @@
+include ../../run-make-fulldeps/tools.mk
+
+# Check that valid binaries are persisted by running them, regardless of whether the --run or --no-run option is used.
+
+all: run no_run
+
+run:
+	mkdir -p $(TMPDIR)/doctests
+	$(RUSTC) --crate-type rlib t.rs
+	$(RUSTDOC) -Zunstable-options --test --persist-doctests $(TMPDIR)/doctests --extern t=$(TMPDIR)/libt.rlib t.rs
+	$(TMPDIR)/doctests/t_rs_2_0/rust_out
+	$(TMPDIR)/doctests/t_rs_8_0/rust_out
+	rm -rf $(TMPDIR)/doctests
+
+no_run:
+	mkdir -p $(TMPDIR)/doctests
+	$(RUSTC) --crate-type rlib t.rs
+	$(RUSTDOC) -Zunstable-options --test --persist-doctests $(TMPDIR)/doctests --extern t=$(TMPDIR)/libt.rlib t.rs --no-run
+	$(TMPDIR)/doctests/t_rs_2_0/rust_out
+	$(TMPDIR)/doctests/t_rs_8_0/rust_out
+	rm -rf $(TMPDIR)/doctests

src/test/run-make/doctests-keep-binaries/t.rs

@@ -0,0 +1,11 @@
+/// Fungle the foople.
+/// ```
+/// t::foople();
+/// ```
+pub fn foople() {}
+
+/// Flomble the florp
+/// ```
+/// t::florp();
+/// ```
+pub fn florp() {}