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The solution is to favor the longest possible nest-name-specifier, and
drop other alternatives by using the guard.
This is my attempt, this might not be a right approach, looking for initial
thoughts.
Motivated cases:
Foo::Foo() {};
// the constructor can be parsed as:
// - Foo ::Foo(); // where the first Foo is return-type, and ::Foo is the
function declarator
// + Foo::Foo(); // where Foo::Foo is the function declarator
void test() {
// a very slow parsing case when there are many qualifers!
X::Y::Z;
// The statement can be parsed as:
// - X ::Y::Z; // ::Y::Z is the declarator
// - X::Y ::Z; // ::Z is the declarator
// + X::Y::Z; // a declaration without declarator (X::Y::Z is
decl-specifier-seq)
// + X::Y::Z; // a qualifed-id expression
}
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D130511
Files:
clang-tools-extra/pseudo/lib/cxx/CXX.cpp
clang-tools-extra/pseudo/lib/cxx/cxx.bnf
Index: clang-tools-extra/pseudo/lib/cxx/cxx.bnf
===================================================================
--- clang-tools-extra/pseudo/lib/cxx/cxx.bnf
+++ clang-tools-extra/pseudo/lib/cxx/cxx.bnf
@@ -370,11 +370,11 @@
defining-type-specifier := enum-specifier
defining-type-specifier-seq := defining-type-specifier
defining-type-specifier-seq := defining-type-specifier
defining-type-specifier-seq [guard]
-simple-type-specifier := nested-name-specifier_opt type-name
+simple-type-specifier := nested-name-specifier_opt type-name [guard]
simple-type-specifier := nested-name-specifier TEMPLATE simple-template-id
simple-type-specifier := decltype-specifier
simple-type-specifier := placeholder-type-specifier
-simple-type-specifier := nested-name-specifier_opt template-name
+simple-type-specifier := nested-name-specifier_opt template-name [guard]
simple-type-specifier := builtin-type
builtin-type := CHAR
builtin-type := CHAR8_T
Index: clang-tools-extra/pseudo/lib/cxx/CXX.cpp
===================================================================
--- clang-tools-extra/pseudo/lib/cxx/CXX.cpp
+++ clang-tools-extra/pseudo/lib/cxx/CXX.cpp
@@ -162,6 +162,10 @@
return symbolToToken(P.Lookahead) != tok::kw_else;
}
+bool guardNextTokenNotColCol(const GuardParams &P) {
+ return symbolToToken(P.Lookahead) != tok::coloncolon;
+}
+
// Whether this e.g. decl-specifier contains an "exclusive" type such as a
class
// name, and thus can't combine with a second exclusive type.
//
@@ -308,6 +312,16 @@
selection_statement_0if_1constexpr_2l_paren_3condition_4r_paren_5statement,
guardNextTokenNotElse},
+ {(RuleID)Rule::simple_type_specifier_0nested_name_specifier_1type_name,
+ guardNextTokenNotColCol},
+
{(RuleID)Rule::simple_type_specifier_0nested_name_specifier_1template_name,
+ guardNextTokenNotColCol},
+ {(RuleID)Rule::simple_type_specifier_0type_name,
+ guardNextTokenNotColCol},
+ {(RuleID)Rule::simple_type_specifier_0template_name,
+ guardNextTokenNotColCol
+ },
+
// The grammar distinguishes (only) user-defined vs plain string
literals,
// where the clang lexer distinguishes (only) encoding types.
{(RuleID)Rule::user_defined_string_literal_chunk_0string_literal,
Index: clang-tools-extra/pseudo/lib/cxx/cxx.bnf
===================================================================
--- clang-tools-extra/pseudo/lib/cxx/cxx.bnf
+++ clang-tools-extra/pseudo/lib/cxx/cxx.bnf
@@ -370,11 +370,11 @@
defining-type-specifier := enum-specifier
defining-type-specifier-seq := defining-type-specifier
defining-type-specifier-seq := defining-type-specifier defining-type-specifier-seq [guard]
-simple-type-specifier := nested-name-specifier_opt type-name
+simple-type-specifier := nested-name-specifier_opt type-name [guard]
simple-type-specifier := nested-name-specifier TEMPLATE simple-template-id
simple-type-specifier := decltype-specifier
simple-type-specifier := placeholder-type-specifier
-simple-type-specifier := nested-name-specifier_opt template-name
+simple-type-specifier := nested-name-specifier_opt template-name [guard]
simple-type-specifier := builtin-type
builtin-type := CHAR
builtin-type := CHAR8_T
Index: clang-tools-extra/pseudo/lib/cxx/CXX.cpp
===================================================================
--- clang-tools-extra/pseudo/lib/cxx/CXX.cpp
+++ clang-tools-extra/pseudo/lib/cxx/CXX.cpp
@@ -162,6 +162,10 @@
return symbolToToken(P.Lookahead) != tok::kw_else;
}
+bool guardNextTokenNotColCol(const GuardParams &P) {
+ return symbolToToken(P.Lookahead) != tok::coloncolon;
+}
+
// Whether this e.g. decl-specifier contains an "exclusive" type such as a class
// name, and thus can't combine with a second exclusive type.
//
@@ -308,6 +312,16 @@
selection_statement_0if_1constexpr_2l_paren_3condition_4r_paren_5statement,
guardNextTokenNotElse},
+ {(RuleID)Rule::simple_type_specifier_0nested_name_specifier_1type_name,
+ guardNextTokenNotColCol},
+ {(RuleID)Rule::simple_type_specifier_0nested_name_specifier_1template_name,
+ guardNextTokenNotColCol},
+ {(RuleID)Rule::simple_type_specifier_0type_name,
+ guardNextTokenNotColCol},
+ {(RuleID)Rule::simple_type_specifier_0template_name,
+ guardNextTokenNotColCol
+ },
+
// The grammar distinguishes (only) user-defined vs plain string literals,
// where the clang lexer distinguishes (only) encoding types.
{(RuleID)Rule::user_defined_string_literal_chunk_0string_literal,
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