extend compiletest to support revisions, incremental tests

COMPILER_TESTS.md

@@ -42,3 +42,43 @@ whole, instead of just a few lines inside the test.
 * `ignore-test` always ignores the test
 * `ignore-lldb` and `ignore-gdb` will skip the debuginfo tests
 * `min-{gdb,lldb}-version`
+* `should-fail` indicates that the test should fail; used for "meta testing",
+  where we test the compiletest program itself to check that it will generate
+  errors in appropriate scenarios. This header is ignored for pretty-printer tests.
+
+## Revisions
+
+Certain classes of tests support "revisions" (as of the time of this
+writing, this includes run-pass, compile-fail, run-fail, and
+incremental, though incremental tests are somewhat
+different). Revisions allow a single test file to be used for multiple
+tests. This is done by adding a special header at the top of the file:
+
+```
+// revisions: foo bar baz
+```
+
+This will result in the test being compiled (and tested) three times,
+once with `--cfg foo`, once with `--cfg bar`, and once with `--cfg
+baz`. You can therefore use `#[cfg(foo)]` etc within the test to tweak
+each of these results.
+
+You can also customize headers and expected error messages to a particular
+revision. To do this, add `[foo]` (or `bar`, `baz`, etc) after the `//`
+comment, like so:
+
+```
+// A flag to pass in only for cfg `foo`:
+//[foo]compile-flags: -Z verbose
+
+#[cfg(foo)]
+fn test_foo() {
+    let x: usize = 32_u32; //[foo]~ ERROR mismatched types
+}
+```
+
+Note that not all headers have meaning when customized too a revision.
+For example, the `ignore-test` header (and all "ignore" headers)
+currently only apply to the test as a whole, not to particular
+revisions. The only headers that are intended to really work when
+customized to a revision are error patterns and compiler flags.

src/compiletest/compiletest.rs

@@ -354,11 +354,25 @@ pub fn is_test(config: &Config, testfile: &Path) -> bool {
 }
 
 pub fn make_test(config: &Config, testpaths: &TestPaths) -> test::TestDescAndFn {
+    let early_props = header::early_props(config, &testpaths.file);
+
+    // The `should-fail` annotation doesn't apply to pretty tests,
+    // since we run the pretty printer across all tests by default.
+    // If desired, we could add a `should-fail-pretty` annotation.
+    let should_panic = match config.mode {
+        Pretty => test::ShouldPanic::No,
+        _ => if early_props.should_fail {
+            test::ShouldPanic::Yes
+        } else {
+            test::ShouldPanic::No
+        }
+    };
+
     test::TestDescAndFn {
         desc: test::TestDesc {
             name: make_test_name(config, testpaths),
-            ignore: header::is_test_ignored(config, &testpaths.file),
-            should_panic: test::ShouldPanic::No,
+            ignore: early_props.ignore,
+            should_panic: should_panic,
         },
         testfn: make_test_closure(config, testpaths),
     }

src/compiletest/errors.rs

@@ -30,8 +30,10 @@ enum WhichLine { ThisLine, FollowPrevious(usize), AdjustBackward(usize) }
 /// Goal is to enable tests both like: //~^^^ ERROR go up three
 /// and also //~^ ERROR message one for the preceding line, and
 ///          //~| ERROR message two for that same line.
-// Load any test directives embedded in the file
-pub fn load_errors(testfile: &Path) -> Vec<ExpectedError> {
+///
+/// If cfg is not None (i.e., in an incremental test), then we look
+/// for `//[X]~` instead, where `X` is the current `cfg`.
+pub fn load_errors(testfile: &Path, cfg: Option<&str>) -> Vec<ExpectedError> {
     let rdr = BufReader::new(File::open(testfile).unwrap());
 
     // `last_nonfollow_error` tracks the most recently seen
@@ -44,30 +46,41 @@ pub fn load_errors(testfile: &Path) -> Vec<ExpectedError> {
     // updating it in the map callback below.)
     let mut last_nonfollow_error = None;
 
-    rdr.lines().enumerate().filter_map(|(line_no, ln)| {
-        parse_expected(last_nonfollow_error,
-                       line_no + 1,
-                       &ln.unwrap())
-            .map(|(which, error)| {
-                match which {
-                    FollowPrevious(_) => {}
-                    _ => last_nonfollow_error = Some(error.line),
-                }
-                error
-            })
-    }).collect()
+    let tag = match cfg {
+        Some(rev) => format!("//[{}]~", rev),
+        None => format!("//~")
+    };
+
+    rdr.lines()
+       .enumerate()
+       .filter_map(|(line_no, ln)| {
+           parse_expected(last_nonfollow_error,
+                          line_no + 1,
+                          &ln.unwrap(),
+                          &tag)
+               .map(|(which, error)| {
+                   match which {
+                       FollowPrevious(_) => {}
+                       _ => last_nonfollow_error = Some(error.line),
+                   }
+                   error
+               })
+       })
+       .collect()
 }
 
 fn parse_expected(last_nonfollow_error: Option<usize>,
                   line_num: usize,
-                  line: &str) -> Option<(WhichLine, ExpectedError)> {
-    let start = match line.find("//~") { Some(i) => i, None => return None };
-    let (follow, adjusts) = if line.char_at(start + 3) == '|' {
+                  line: &str,
+                  tag: &str)
+                  -> Option<(WhichLine, ExpectedError)> {
+    let start = match line.find(tag) { Some(i) => i, None => return None };
+    let (follow, adjusts) = if line.char_at(start + tag.len()) == '|' {
         (true, 0)
     } else {
-        (false, line[start + 3..].chars().take_while(|c| *c == '^').count())
+        (false, line[start + tag.len()..].chars().take_while(|c| *c == '^').count())
     };
-    let kind_start = start + 3 + adjusts + (follow as usize);
+    let kind_start = start + tag.len() + adjusts + (follow as usize);
     let letters = line[kind_start..].chars();
     let kind = letters.skip_while(|c| c.is_whitespace())
                       .take_while(|c| !c.is_whitespace())
@@ -91,7 +104,9 @@ fn parse_expected(last_nonfollow_error: Option<usize>,
         (which, line)
     };
 
-    debug!("line={} which={:?} kind={:?} msg={:?}", line_num, which, kind, msg);
+    debug!("line={} tag={:?} which={:?} kind={:?} msg={:?}",
+           line_num, tag, which, kind, msg);
+
     Some((which, ExpectedError { line: line,
                                  kind: kind,
                                  msg: msg, }))