Add support for ! negate gitignore patterns.

src/cargo/sources/path.rs

@@ -138,8 +138,16 @@ impl<'cfg> PathSource<'cfg> {
             .map(|p| glob_parse(p))
             .collect::<Result<Vec<_>, _>>();
 
+        // Don't warn if using a negate pattern, since those weren't ever
+        // previously supported.
+        let has_negate = pkg
+            .manifest()
+            .exclude()
+            .iter()
+            .chain(pkg.manifest().include().iter())
+            .any(|p| p.starts_with("!"));
         // Don't warn about glob mismatch if it doesn't parse.
-        let glob_is_valid = glob_exclude.is_ok() && glob_include.is_ok();
+        let glob_is_valid = glob_exclude.is_ok() && glob_include.is_ok() && !has_negate;
         let glob_exclude = glob_exclude.unwrap_or_else(|_| Vec::new());
         let glob_include = glob_include.unwrap_or_else(|_| Vec::new());
 
@@ -180,10 +188,7 @@ impl<'cfg> PathSource<'cfg> {
                 {
                     Match::None => Ok(true),
                     Match::Ignore(_) => Ok(false),
-                    Match::Whitelist(pattern) => Err(failure::format_err!(
-                        "exclude rules cannot start with `!`: {}",
-                        pattern.original()
-                    )),
+                    Match::Whitelist(_) => Ok(true),
                 }
             } else {
                 match ignore_include
@@ -191,10 +196,7 @@ impl<'cfg> PathSource<'cfg> {
                 {
                     Match::None => Ok(false),
                     Match::Ignore(_) => Ok(true),
-                    Match::Whitelist(pattern) => Err(failure::format_err!(
-                        "include rules cannot start with `!`: {}",
-                        pattern.original()
-                    )),
+                    Match::Whitelist(_) => Ok(false),
                 }
             }
         };

src/doc/src/reference/manifest.md

@@ -148,7 +148,9 @@ The patterns should be [gitignore]-style patterns. Briefly:
   `foo`.
 - `/**/` matches zero or more directories. For example, `a/**/b` matches
   `a/b`, `a/x/b`, `a/x/y/b`, and so on.
-- `!` prefixed patterns are not supported.
+- `!` prefix negates a pattern. For example, a pattern of `src/**.rs` and
+  `!foo.rs` would match all files with the `.rs` extension inside the `src`
+  directory, except for any file named `foo.rs`.
 
 If git is being used for a package, the `exclude` field will be seeded with
 the `gitignore` settings from the repository.

tests/testsuite/package.rs

@@ -1152,7 +1152,13 @@ fn include_cargo_toml_implicit() {
         .run();
 }
 
-fn include_exclude_test(include: &str, exclude: &str, files: &[&str], expected: &str) {
+fn include_exclude_test(
+    include: &str,
+    exclude: &str,
+    files: &[&str],
+    expected: &str,
+    has_warnings: bool,
+) {
     let mut pb = project().file(
         "Cargo.toml",
         &format!(
@@ -1177,10 +1183,13 @@ fn include_exclude_test(include: &str, exclude: &str, files: &[&str], expected:
     }
     let p = pb.build();
 
-    p.cargo("package --list")
-        .with_stdout(expected)
-        // .with_stderr("") Add this back when warnings are removed.
-        .run();
+    let mut e = p.cargo("package --list");
+    if has_warnings {
+        e.with_stderr_contains("[..]");
+    } else {
+        e.with_stderr("");
+    }
+    e.with_stdout(expected).run();
     p.root().rm_rf();
 }
 
@@ -1201,6 +1210,7 @@ fn package_include_ignore_only() {
          src/abc2.rs\n\
          src/lib.rs\n\
          ",
+        false,
     )
 }
 
@@ -1216,6 +1226,7 @@ fn gitignore_patterns() {
          foo\n\
          x/foo/y\n\
          ",
+        true,
     );
 
     include_exclude_test(
@@ -1225,6 +1236,7 @@ fn gitignore_patterns() {
         "Cargo.toml\n\
          foo\n\
          ",
+        false,
     );
 
     include_exclude_test(
@@ -1237,6 +1249,7 @@ fn gitignore_patterns() {
          foo\n\
          src/lib.rs\n\
          ",
+        true,
     );
 
     include_exclude_test(
@@ -1259,6 +1272,7 @@ fn gitignore_patterns() {
          other\n\
          src/lib.rs\n\
          ",
+        false,
     );
 
     include_exclude_test(
@@ -1268,6 +1282,7 @@ fn gitignore_patterns() {
         "Cargo.toml\n\
          a/foo/bar\n\
          ",
+        false,
     );
 
     include_exclude_test(
@@ -1277,6 +1292,7 @@ fn gitignore_patterns() {
         "Cargo.toml\n\
          foo/x/y/z\n\
          ",
+        false,
     );
 
     include_exclude_test(
@@ -1288,5 +1304,54 @@ fn gitignore_patterns() {
          a/x/b\n\
          a/x/y/b\n\
          ",
+        false,
+    );
+}
+
+#[test]
+fn gitignore_negate() {
+    include_exclude_test(
+        r#"["Cargo.toml", "*.rs", "!foo.rs", "\\!important"]"#, // include
+        "[]",
+        &["src/lib.rs", "foo.rs", "!important"],
+        "!important\n\
+         Cargo.toml\n\
+         src/lib.rs\n\
+         ",
+        false,
+    );
+
+    // NOTE: This is unusual compared to git. Git treats `src/` as a
+    // short-circuit which means rules like `!src/foo.rs` would never run.
+    // However, because Cargo only works by iterating over *files*, it doesn't
+    // short-circuit.
+    include_exclude_test(
+        r#"["Cargo.toml", "src/", "!src/foo.rs"]"#, // include
+        "[]",
+        &["src/lib.rs", "src/foo.rs"],
+        "Cargo.toml\n\
+         src/lib.rs\n\
+         ",
+        false,
+    );
+
+    include_exclude_test(
+        r#"["Cargo.toml", "src/**.rs", "!foo.rs"]"#, // include
+        "[]",
+        &["src/lib.rs", "foo.rs", "src/foo.rs", "src/bar/foo.rs"],
+        "Cargo.toml\n\
+         src/lib.rs\n\
+         ",
+        false,
+    );
+
+    include_exclude_test(
+        "[]",
+        r#"["*.rs", "!foo.rs", "\\!important"]"#, // exclude
+        &["src/lib.rs", "foo.rs", "!important"],
+        "Cargo.toml\n\
+         foo.rs\n\
+         ",
+        false,
     );
 }