Rollup merge of #49451 - QuietMisdreavus:epoch-doctests, r=GuillaumeGomez

rustdoc: add an --edition flag to compile docs/doctests with a certain edition

To correspond with the 2018 edition, this adds a (currently unstable) `--edition` flag to rustdoc that makes it compile crates and doctests with the given edition. Once this lands, Cargo should be updated to pass this flag when the edition configuration option is given.

src/librustdoc/test.rs

@@ -34,6 +34,7 @@ use rustc_metadata::cstore::CStore;
 use rustc_resolve::MakeGlobMap;
 use syntax::ast;
 use syntax::codemap::CodeMap;
+use syntax::edition::Edition;
 use syntax::feature_gate::UnstableFeatures;
 use syntax::with_globals;
 use syntax_pos::{BytePos, DUMMY_SP, Pos, Span, FileName};
@@ -57,7 +58,8 @@ pub fn run(input_path: &Path,
            crate_name: Option<String>,
            maybe_sysroot: Option<PathBuf>,
            display_warnings: bool,
-           linker: Option<PathBuf>)
+           linker: Option<PathBuf>,
+           edition: Edition)
            -> isize {
     let input = config::Input::File(input_path.to_owned());
 
@@ -70,6 +72,10 @@ pub fn run(input_path: &Path,
         unstable_features: UnstableFeatures::from_environment(),
         lint_cap: Some(::rustc::lint::Level::Allow),
         actually_rustdoc: true,
+        debugging_opts: config::DebuggingOptions {
+            edition,
+            ..config::basic_debugging_options()
+        },
         ..config::basic_options().clone()
     };
 
@@ -117,7 +123,8 @@ pub fn run(input_path: &Path,
                                        maybe_sysroot,
                                        Some(codemap),
                                        None,
-                                       linker);
+                                       linker,
+                                       edition);
 
     {
         let map = hir::map::map_crate(&sess, &cstore, &mut hir_forest, &defs);
@@ -177,8 +184,7 @@ fn run_test(test: &str, cratename: &str, filename: &FileName, line: usize,
             externs: Externs,
             should_panic: bool, no_run: bool, as_test_harness: bool,
             compile_fail: bool, mut error_codes: Vec<String>, opts: &TestOptions,
-            maybe_sysroot: Option<PathBuf>,
-            linker: Option<PathBuf>) {
+            maybe_sysroot: Option<PathBuf>, linker: Option<PathBuf>, edition: Edition) {
     // the test harness wants its own `main` & top level functions, so
     // never wrap the test in `fn main() { ... }`
     let (test, line_offset) = make_test(test, Some(cratename), as_test_harness, opts);
@@ -204,6 +210,10 @@ fn run_test(test: &str, cratename: &str, filename: &FileName, line: usize,
         },
         test: as_test_harness,
         unstable_features: UnstableFeatures::from_environment(),
+        debugging_opts: config::DebuggingOptions {
+            edition,
+            ..config::basic_debugging_options()
+        },
         ..config::basic_options().clone()
     };
 
@@ -465,13 +475,14 @@ pub struct Collector {
     codemap: Option<Lrc<CodeMap>>,
     filename: Option<PathBuf>,
     linker: Option<PathBuf>,
+    edition: Edition,
 }
 
 impl Collector {
     pub fn new(cratename: String, cfgs: Vec<String>, libs: SearchPaths, externs: Externs,
                use_headers: bool, opts: TestOptions, maybe_sysroot: Option<PathBuf>,
                codemap: Option<Lrc<CodeMap>>, filename: Option<PathBuf>,
-               linker: Option<PathBuf>) -> Collector {
+               linker: Option<PathBuf>, edition: Edition) -> Collector {
         Collector {
             tests: Vec::new(),
             names: Vec::new(),
@@ -486,6 +497,7 @@ impl Collector {
             codemap,
             filename,
             linker,
+            edition,
         }
     }
 
@@ -505,6 +517,7 @@ impl Collector {
         let opts = self.opts.clone();
         let maybe_sysroot = self.maybe_sysroot.clone();
         let linker = self.linker.clone();
+        let edition = self.edition;
         debug!("Creating test {}: {}", name, test);
         self.tests.push(testing::TestDescAndFn {
             desc: testing::TestDesc {
@@ -535,7 +548,8 @@ impl Collector {
                                  error_codes,
                                  &opts,
                                  maybe_sysroot,
-                                 linker)
+                                 linker,
+                                 edition)
                     }))
                 } {
                     Ok(()) => (),