riccibruno created this revision.
riccibruno added reviewers: rsmith, aaron.ballman.
riccibruno added a project: clang.
Herald added a subscriber: cfe-commits.
Currently a capture-default which is not the first element in the
lambda-capture is diagnosed with a generic `expected variable name or 'this' in
lambda capture list`, which is true but not very helpful.
If we don't have already parsed a capture-default then a lone "&" or "=" is
likely to be a misplaced capture-default, so diagnose it as such.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D83681
Files:
clang/include/clang/Basic/DiagnosticParseKinds.td
clang/lib/Parse/ParseExprCXX.cpp
clang/test/Parser/lambda-misplaced-capture-default.cpp
Index: clang/test/Parser/lambda-misplaced-capture-default.cpp
===================================================================
--- /dev/null
+++ clang/test/Parser/lambda-misplaced-capture-default.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -std=c++17 -Wno-unused-value -fsyntax-only -verify %s
+
+namespace misplaced_capture_default {
+void Test() {
+ int i = 0;
+ [&, i, &] {}; // expected-error {{expected variable name or 'this' in
lambda capture list}}
+ [&, i, = ] {}; // expected-error {{expected variable name or 'this' in
lambda capture list}}
+ [=, &i, &] {}; // expected-error {{expected variable name or 'this' in
lambda capture list}}
+ [=, &i, = ] {}; // expected-error {{expected variable name or 'this' in
lambda capture list}}
+
+ [i, &] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+
+ [i, = ] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+
+ [i, = x] {}; // expected-error {{expected variable name or 'this' in
lambda capture list}}
+
+ [i, &, x = 2] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+
+ [i, =, x = 2] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+}
+} // namespace misplaced_capture_default
Index: clang/lib/Parse/ParseExprCXX.cpp
===================================================================
--- clang/lib/Parse/ParseExprCXX.cpp
+++ clang/lib/Parse/ParseExprCXX.cpp
@@ -926,6 +926,17 @@
} else if (Tok.is(tok::kw_this)) {
Kind = LCK_This;
Loc = ConsumeToken();
+ } else if (Tok.isOneOf(tok::amp, tok::equal) &&
+ NextToken().isOneOf(tok::comma, tok::r_square) &&
+ Intro.Default == LCD_None) {
+ // We have a lone "&" or "=" which is either a misplaced capture-default
+ // or the start of a capture (in the "&" case) with the rest of the
+ // capture missing. Both are an error but a misplaced capture-default
+ // is more likely if we don't already have a capture default.
+ return Invalid([&] {
+ Diag(Tok.getLocation(), diag::err_misplaced_capture_default);
+ Diag(T.getOpenLocation(), diag::note_capture_default_first);
+ });
} else {
TryConsumeToken(tok::ellipsis, EllipsisLocs[0]);
Index: clang/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticParseKinds.td
+++ clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -934,6 +934,10 @@
"the name of the capture">;
def err_lambda_capture_multiple_ellipses : Error<
"multiple ellipses in pack capture">;
+def err_misplaced_capture_default : Error<
+ "misplaced capture default">;
+def note_capture_default_first : Note<
+ "capture default must be first">;
// C++17 lambda expressions
def err_expected_star_this_capture : Error<
"expected 'this' following '*' in lambda capture list">;
Index: clang/test/Parser/lambda-misplaced-capture-default.cpp
===================================================================
--- /dev/null
+++ clang/test/Parser/lambda-misplaced-capture-default.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -std=c++17 -Wno-unused-value -fsyntax-only -verify %s
+
+namespace misplaced_capture_default {
+void Test() {
+ int i = 0;
+ [&, i, &] {}; // expected-error {{expected variable name or 'this' in lambda capture list}}
+ [&, i, = ] {}; // expected-error {{expected variable name or 'this' in lambda capture list}}
+ [=, &i, &] {}; // expected-error {{expected variable name or 'this' in lambda capture list}}
+ [=, &i, = ] {}; // expected-error {{expected variable name or 'this' in lambda capture list}}
+
+ [i, &] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+
+ [i, = ] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+
+ [i, = x] {}; // expected-error {{expected variable name or 'this' in lambda capture list}}
+
+ [i, &, x = 2] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+
+ [i, =, x = 2] {}; // expected-error {{misplaced capture default}}
+ // expected-note@-1 {{capture default must be first}}
+}
+} // namespace misplaced_capture_default
Index: clang/lib/Parse/ParseExprCXX.cpp
===================================================================
--- clang/lib/Parse/ParseExprCXX.cpp
+++ clang/lib/Parse/ParseExprCXX.cpp
@@ -926,6 +926,17 @@
} else if (Tok.is(tok::kw_this)) {
Kind = LCK_This;
Loc = ConsumeToken();
+ } else if (Tok.isOneOf(tok::amp, tok::equal) &&
+ NextToken().isOneOf(tok::comma, tok::r_square) &&
+ Intro.Default == LCD_None) {
+ // We have a lone "&" or "=" which is either a misplaced capture-default
+ // or the start of a capture (in the "&" case) with the rest of the
+ // capture missing. Both are an error but a misplaced capture-default
+ // is more likely if we don't already have a capture default.
+ return Invalid([&] {
+ Diag(Tok.getLocation(), diag::err_misplaced_capture_default);
+ Diag(T.getOpenLocation(), diag::note_capture_default_first);
+ });
} else {
TryConsumeToken(tok::ellipsis, EllipsisLocs[0]);
Index: clang/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticParseKinds.td
+++ clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -934,6 +934,10 @@
"the name of the capture">;
def err_lambda_capture_multiple_ellipses : Error<
"multiple ellipses in pack capture">;
+def err_misplaced_capture_default : Error<
+ "misplaced capture default">;
+def note_capture_default_first : Note<
+ "capture default must be first">;
// C++17 lambda expressions
def err_expected_star_this_capture : Error<
"expected 'this' following '*' in lambda capture list">;
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