[flang-commits] [flang] [flang][parser] Better error recovery for SUBROUTINE/FUNCTION statements (PR #100664)
Peter Klausler via flang-commits
flang-commits at lists.llvm.org
Mon Jul 29 12:09:11 PDT 2024
https://github.com/klausler updated https://github.com/llvm/llvm-project/pull/100664
>From 7a012671ab2de5bd01726f0d6195a1d3d9a14727 Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler at nvidia.com>
Date: Thu, 25 Jul 2024 15:35:52 -0700
Subject: [PATCH] [flang][parser] Better error recovery for SUBROUTINE/FUNCTION
statements
When there's an error in a SUBROUTINE or FUNCTION statement,
errors cascade quickly because the body of the subprogram or
interface isn't in the right context. So, if a SUBROUTINE or
FUNCTION statement is expected, and contains a SUBROUTINE or
FUNCTION keyword, it counts as one -- retain and emit any errors
pertaining to the arguments or suffix, recover to the end of the
line if needed, and proceed.
---
flang/lib/Parser/program-parsers.cpp | 48 ++++++++++++++++++++--------
flang/lib/Parser/stmt-parser.h | 6 ++--
flang/test/Parser/recovery04.f90 | 24 ++++++++++++++
3 files changed, 63 insertions(+), 15 deletions(-)
create mode 100644 flang/test/Parser/recovery04.f90
diff --git a/flang/lib/Parser/program-parsers.cpp b/flang/lib/Parser/program-parsers.cpp
index b51b60157f39c..125df18407970 100644
--- a/flang/lib/Parser/program-parsers.cpp
+++ b/flang/lib/Parser/program-parsers.cpp
@@ -34,12 +34,27 @@ namespace Fortran::parser {
// for several productions; giving the "module" production priority here is a
// cleaner solution, though regrettably subtle.
// Enforcing C1547 is done in semantics.
+static constexpr auto notATopLevelFunctionStmt{
+ // REAL FUNCTIONF at the top level is the first declaration of a main
+ // program
+ // REAL FUNCTION is too
+ // REAL FUNCTION F(10) is too
+ // REAL FUNCTION F/1./ is too
+ // REAL FUNCTION F,G is too
+ // REAL FUNCTION F(X) is a FunctionStmt
+ // REAL FUNCTION F can be a FunctionStmt
+ declarationTypeSpec >> "FUNCTION"_sptok >>
+ (!lookAhead(letter || underscore) >> name >> atEndOfStmt || !name ||
+ !(name >>
+ (extension<LanguageFeature::OmitFunctionDummies>(atEndOfStmt) ||
+ parenthesized(optionalList(name)) >> ok)))};
static constexpr auto programUnit{
construct<ProgramUnit>(indirect(Parser<Module>{})) ||
- construct<ProgramUnit>(indirect(functionSubprogram)) ||
construct<ProgramUnit>(indirect(subroutineSubprogram)) ||
construct<ProgramUnit>(indirect(Parser<Submodule>{})) ||
construct<ProgramUnit>(indirect(Parser<BlockData>{})) ||
+ !notATopLevelFunctionStmt >>
+ construct<ProgramUnit>(indirect(functionSubprogram)) ||
construct<ProgramUnit>(indirect(Parser<MainProgram>{}))};
static constexpr auto normalProgramUnit{StartNewSubprogram{} >> programUnit /
skipMany(";"_tok) / space / recovery(endOfLine, SkipPast<'\n'>{})};
@@ -532,15 +547,20 @@ TYPE_CONTEXT_PARSER("FUNCTION subprogram"_en_US,
// [prefix] FUNCTION function-name ( [dummy-arg-name-list] ) [suffix]
// R1526 prefix -> prefix-spec [prefix-spec]...
// R1531 dummy-arg-name -> name
-TYPE_CONTEXT_PARSER("FUNCTION statement"_en_US,
- construct<FunctionStmt>(many(prefixSpec), "FUNCTION" >> name,
- parenthesized(optionalList(name)), maybe(suffix)) ||
+
+TYPE_PARSER(construct<FunctionStmt>(many(prefixSpec), "FUNCTION" >> name,
+ parenthesized(optionalList(name)), maybe(suffix)) /
+ atEndOfStmt ||
+ construct<FunctionStmt>(many(prefixSpec), "FUNCTION" >> name / atEndOfStmt,
+ // PGI & Intel accept "FUNCTION F"
extension<LanguageFeature::OmitFunctionDummies>(
"nonstandard usage: FUNCTION statement without dummy argument list"_port_en_US,
- construct<FunctionStmt>( // PGI & Intel accept "FUNCTION F"
- many(prefixSpec), "FUNCTION" >> name,
- construct<std::list<Name>>(),
- construct<std::optional<Suffix>>())))
+ pure<std::list<Name>>()),
+ pure<std::optional<Suffix>>()) ||
+ // error recovery
+ construct<FunctionStmt>(many(prefixSpec), "FUNCTION" >> name,
+ defaulted(parenthesized(optionalList(name))), maybe(suffix)) /
+ checkEndOfKnownStmt)
// R1532 suffix ->
// proc-language-binding-spec [RESULT ( result-name )] |
@@ -566,11 +586,13 @@ TYPE_CONTEXT_PARSER("SUBROUTINE subprogram"_en_US,
// [prefix] SUBROUTINE subroutine-name [( [dummy-arg-list] )
// [proc-language-binding-spec]]
TYPE_PARSER(
- construct<SubroutineStmt>(many(prefixSpec), "SUBROUTINE" >> name,
- parenthesized(optionalList(dummyArg)), maybe(languageBindingSpec)) ||
- construct<SubroutineStmt>(many(prefixSpec), "SUBROUTINE" >> name,
- pure<std::list<DummyArg>>(),
- pure<std::optional<LanguageBindingSpec>>()))
+ (construct<SubroutineStmt>(many(prefixSpec), "SUBROUTINE" >> name,
+ !"("_tok >> pure<std::list<DummyArg>>(),
+ pure<std::optional<LanguageBindingSpec>>()) ||
+ construct<SubroutineStmt>(many(prefixSpec), "SUBROUTINE" >> name,
+ defaulted(parenthesized(optionalList(dummyArg))),
+ maybe(languageBindingSpec))) /
+ checkEndOfKnownStmt)
// R1536 dummy-arg -> dummy-arg-name | *
TYPE_PARSER(construct<DummyArg>(name) || construct<DummyArg>(star))
diff --git a/flang/lib/Parser/stmt-parser.h b/flang/lib/Parser/stmt-parser.h
index ba647fd60d4ae..00bae2bf950c8 100644
--- a/flang/lib/Parser/stmt-parser.h
+++ b/flang/lib/Parser/stmt-parser.h
@@ -30,6 +30,10 @@ inline constexpr auto unterminatedStatement(const PA &p) {
maybe(label), space >> p));
}
+constexpr auto atEndOfStmt{space >>
+ withMessage("expected end of statement"_err_en_US, lookAhead(";\n"_ch))};
+constexpr auto checkEndOfKnownStmt{recovery(atEndOfStmt, SkipTo<'\n'>{})};
+
constexpr auto endOfLine{
"\n"_ch >> ok || fail("expected end of line"_err_en_US)};
@@ -86,8 +90,6 @@ constexpr auto executionPartErrorRecovery{stmtErrorRecoveryStart >>
// END statement error recovery
constexpr auto missingOptionalName{pure<std::optional<Name>>()};
constexpr auto noNameEnd{"END" >> missingOptionalName};
-constexpr auto atEndOfStmt{space >>
- withMessage("expected end of statement"_err_en_US, lookAhead(";\n"_ch))};
constexpr auto bareEnd{noNameEnd / recovery(atEndOfStmt, SkipTo<'\n'>{})};
// For unrecognizable construct END statements. Be sure to not consume
diff --git a/flang/test/Parser/recovery04.f90 b/flang/test/Parser/recovery04.f90
new file mode 100644
index 0000000000000..144ebd24f71b5
--- /dev/null
+++ b/flang/test/Parser/recovery04.f90
@@ -0,0 +1,24 @@
+! RUN: not %flang_fc1 -fsyntax-only %s 2>&1 | FileCheck %s
+module m
+ contains
+ !CHECK: expected end of statement
+ !CHECK: subroutine s1(var i, j)
+ subroutine s1(var i, j)
+ end subroutine
+ !CHECK: expected end of statement
+ !CHECK: subroutine s2[b]
+ subroutine s2[b]
+ end subroutine
+ !CHECK: expected end of statement
+ !CHECK: function f1(var i, j)
+ function f1(var i, j)
+ end function
+ !CHECK: expected end of statement
+ !CHECK: function f2[b]
+ function f2[b]
+ end function
+ !CHECK: expected end of statement
+ !CHECK: function f3(a,*)
+ function f3(a,*)
+ end function
+end
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