Use more precise span when reporting semicolon hint

When reporting "consider removing this semicolon" hint message, the
offending semicolon may come from macro call site instead of macro
itself. Using the more appropriate span makes the hint more helpful.

Closes #13428.

3 files changed, 23 insertions, 14 deletions

diff --git a/src/libsyntax/codemap.rs b/src/libsyntax/codemap.rs
index b174dffdfec..3c890189ed9 100644
--- a/src/libsyntax/codemap.rs
+++ b/src/libsyntax/codemap.rs
@@ -141,6 +141,17 @@ pub fn mk_sp(lo: BytePos, hi: BytePos) -> Span {
     Span {lo: lo, hi: hi, expn_info: None}
 }
 
+/// Return the span itself if it doesn't come from a macro expansion,
+/// otherwise return the call site span up to the `enclosing_sp` by
+/// following the `expn_info` chain.
+pub fn original_sp(sp: Span, enclosing_sp: Span) -> Span {
+    match (sp.expn_info, enclosing_sp.expn_info) {
+        (None, _) => sp,
+        (Some(expn1), Some(expn2)) if expn1.call_site == expn2.call_site => sp,
+        (Some(expn1), _) => original_sp(expn1.call_site, enclosing_sp),
+    }
+}
+
 /// A source code location used for error reporting
 pub struct Loc {
     /// Information about the original source
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index eca9f955d93..f83ee200c9e 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -686,7 +686,7 @@ mod test {
                                                       }),
                                                 span: sp(17,18)},
                                                 ast::DUMMY_NODE_ID),
-                                            span: sp(17,18)}),
+                                            span: sp(17,19)}),
                                         expr: None,
                                         id: ast::DUMMY_NODE_ID,
                                         rules: ast::DefaultBlock, // no idea
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 379403e5409..6943d03e6f1 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -3260,9 +3260,14 @@ impl<'a> Parser<'a> {
                             match self.token {
                                 token::SEMI => {
                                     self.bump();
+                                    let span_with_semi = Span {
+                                        lo: stmt.span.lo,
+                                        hi: self.last_span.hi,
+                                        expn_info: stmt.span.expn_info,
+                                    };
                                     stmts.push(@codemap::Spanned {
                                         node: StmtSemi(e, stmt_id),
-                                        span: stmt.span,
+                                        span: span_with_semi,
                                     });
                                 }
                                 token::RBRACE => {
@@ -3275,33 +3280,26 @@ impl<'a> Parser<'a> {
                         }
                         StmtMac(ref m, _) => {
                             // statement macro; might be an expr
-                            let has_semi;
                             match self.token {
                                 token::SEMI => {
-                                    has_semi = true;
+                                    self.bump();
+                                    stmts.push(@codemap::Spanned {
+                                        node: StmtMac((*m).clone(), true),
+                                        span: stmt.span,
+                                    });
                                 }
                                 token::RBRACE => {
                                     // if a block ends in `m!(arg)` without
                                     // a `;`, it must be an expr
-                                    has_semi = false;
                                     expr = Some(
                                         self.mk_mac_expr(stmt.span.lo,
                                                          stmt.span.hi,
                                                          m.node.clone()));
                                 }
                                 _ => {
-                                    has_semi = false;
                                     stmts.push(stmt);
                                 }
                             }
-
-                            if has_semi {
-                                self.bump();
-                                stmts.push(@codemap::Spanned {
-                                    node: StmtMac((*m).clone(), true),
-                                    span: stmt.span,
-                                });
-                            }
                         }
                         _ => { // all other kinds of statements:
                             stmts.push(stmt);