[flang-commits] [flang] [flang] More information on generic resolution failures (PR #164738)
Peter Klausler via flang-commits
flang-commits at lists.llvm.org
Fri Oct 24 06:26:21 PDT 2025
https://github.com/klausler updated https://github.com/llvm/llvm-project/pull/164738
>From 4d238b7415b9370c1961cff1a3980c454cb94098 Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler at nvidia.com>
Date: Wed, 22 Oct 2025 17:20:43 -0700
Subject: [PATCH] [flang] More information on generic resolution failures
When a generic procedure reference does not match any of its
specific procedures, run through them and emit the errors for each
attempted match, so that the user has more information to
resolve the problem by adjusting the actual arguments.
---
flang/include/flang/Evaluate/call.h | 1 +
flang/include/flang/Semantics/expression.h | 14 ++-
flang/lib/Evaluate/formatting.cpp | 7 ++
flang/lib/Semantics/check-call.cpp | 7 +-
flang/lib/Semantics/check-call.h | 11 ++-
flang/lib/Semantics/expression.cpp | 105 +++++++++++++--------
flang/test/Semantics/generic-error.f90 | 21 +++++
7 files changed, 116 insertions(+), 50 deletions(-)
create mode 100644 flang/test/Semantics/generic-error.f90
diff --git a/flang/include/flang/Evaluate/call.h b/flang/include/flang/Evaluate/call.h
index 2a5929b873d74..fea09d6440226 100644
--- a/flang/include/flang/Evaluate/call.h
+++ b/flang/include/flang/Evaluate/call.h
@@ -112,6 +112,7 @@ class ActualArgument {
int Rank() const;
bool operator==(const ActualArgument &) const;
llvm::raw_ostream &AsFortran(llvm::raw_ostream &) const;
+ std::string AsFortran() const;
std::optional<parser::CharBlock> keyword() const { return keyword_; }
ActualArgument &set_keyword(parser::CharBlock x) {
diff --git a/flang/include/flang/Semantics/expression.h b/flang/include/flang/Semantics/expression.h
index 95c97f264a667..713e81e703f45 100644
--- a/flang/include/flang/Semantics/expression.h
+++ b/flang/include/flang/Semantics/expression.h
@@ -367,11 +367,17 @@ class ExpressionAnalyzer {
using AdjustActuals =
std::optional<std::function<bool(const Symbol &, ActualArguments &)>>;
const Symbol *ResolveForward(const Symbol &);
- std::pair<const Symbol *, bool /* failure due ambiguity */> ResolveGeneric(
+ struct GenericResolution {
+ const Symbol *specific{nullptr};
+ bool failedDueToAmbiguity{false};
+ SymbolVector tried;
+ };
+ GenericResolution ResolveGeneric(
const Symbol &, const ActualArguments &, const AdjustActuals &,
- bool isSubroutine, bool mightBeStructureConstructor = false);
- void EmitGenericResolutionError(
- const Symbol &, bool dueToNullActuals, bool isSubroutine);
+ bool isSubroutine, SymbolVector &&tried,
+ bool mightBeStructureConstructor = false);
+ void EmitGenericResolutionError(const Symbol &, bool dueToNullActuals,
+ bool isSubroutine, ActualArguments &, const SymbolVector &);
const Symbol &AccessSpecific(
const Symbol &originalGeneric, const Symbol &specific);
std::optional<CalleeAndArguments> GetCalleeAndArguments(const parser::Name &,
diff --git a/flang/lib/Evaluate/formatting.cpp b/flang/lib/Evaluate/formatting.cpp
index ec5dc0baaa5cb..5632015857ab3 100644
--- a/flang/lib/Evaluate/formatting.cpp
+++ b/flang/lib/Evaluate/formatting.cpp
@@ -252,6 +252,13 @@ llvm::raw_ostream &ActualArgument::AsFortran(llvm::raw_ostream &o) const {
return o;
}
+std::string ActualArgument::AsFortran() const {
+ std::string result;
+ llvm::raw_string_ostream sstream(result);
+ AsFortran(sstream);
+ return result;
+}
+
llvm::raw_ostream &SpecificIntrinsic::AsFortran(llvm::raw_ostream &o) const {
return o << name;
}
diff --git a/flang/lib/Semantics/check-call.cpp b/flang/lib/Semantics/check-call.cpp
index e4d2a0d220c12..c51d40b9e5039 100644
--- a/flang/lib/Semantics/check-call.cpp
+++ b/flang/lib/Semantics/check-call.cpp
@@ -2241,10 +2241,9 @@ static void CheckSpecificIntrinsic(const characteristics::Procedure &proc,
}
}
-static parser::Messages CheckExplicitInterface(
- const characteristics::Procedure &proc, evaluate::ActualArguments &actuals,
- SemanticsContext &context, const Scope *scope,
- const evaluate::SpecificIntrinsic *intrinsic,
+parser::Messages CheckExplicitInterface(const characteristics::Procedure &proc,
+ evaluate::ActualArguments &actuals, SemanticsContext &context,
+ const Scope *scope, const evaluate::SpecificIntrinsic *intrinsic,
bool allowActualArgumentConversions, bool extentErrors,
bool ignoreImplicitVsExplicit) {
evaluate::FoldingContext &foldingContext{context.foldingContext()};
diff --git a/flang/lib/Semantics/check-call.h b/flang/lib/Semantics/check-call.h
index 46bc61a601bd3..a69b792b646e6 100644
--- a/flang/lib/Semantics/check-call.h
+++ b/flang/lib/Semantics/check-call.h
@@ -12,11 +12,8 @@
#define FORTRAN_SEMANTICS_CHECK_CALL_H_
#include "flang/Evaluate/call.h"
+#include "flang/Parser/message.h"
-namespace Fortran::parser {
-class Messages;
-class ContextualMessages;
-} // namespace Fortran::parser
namespace Fortran::evaluate::characteristics {
struct Procedure;
}
@@ -47,6 +44,12 @@ bool CheckArgumentIsConstantExprInRange(
const evaluate::ActualArguments &actuals, int index, int lowerBound,
int upperBound, parser::ContextualMessages &messages);
+parser::Messages CheckExplicitInterface(
+ const evaluate::characteristics::Procedure &, evaluate::ActualArguments &,
+ SemanticsContext &, const Scope *, const evaluate::SpecificIntrinsic *,
+ bool allowActualArgumentConversions, bool extentErrors,
+ bool ignoreImplicitVsExplicit);
+
// Checks actual arguments for the purpose of resolving a generic interface.
bool CheckInterfaceForGeneric(const evaluate::characteristics::Procedure &,
evaluate::ActualArguments &, SemanticsContext &,
diff --git a/flang/lib/Semantics/expression.cpp b/flang/lib/Semantics/expression.cpp
index 4aeb9a44088e2..0ae9f3b32990e 100644
--- a/flang/lib/Semantics/expression.cpp
+++ b/flang/lib/Semantics/expression.cpp
@@ -2552,11 +2552,11 @@ auto ExpressionAnalyzer::AnalyzeProcedureComponentRef(
}
return true;
}};
- auto pair{
- ResolveGeneric(generic, arguments, adjustment, isSubroutine)};
- sym = pair.first;
+ auto result{ResolveGeneric(generic, arguments, adjustment, isSubroutine, SymbolVector{})};
+ sym = result.specific;
if (!sym) {
- EmitGenericResolutionError(generic, pair.second, isSubroutine);
+ EmitGenericResolutionError(
+ generic, result.failedDueToAmbiguity, isSubroutine, arguments, result.tried);
return std::nullopt;
}
// re-resolve the name to the specific binding
@@ -2886,10 +2886,11 @@ const Symbol *ExpressionAnalyzer::ResolveForward(const Symbol &symbol) {
// Resolve a call to a generic procedure with given actual arguments.
// adjustActuals is called on procedure bindings to handle pass arg.
-std::pair<const Symbol *, bool> ExpressionAnalyzer::ResolveGeneric(
+auto ExpressionAnalyzer::ResolveGeneric(
const Symbol &symbol, const ActualArguments &actuals,
const AdjustActuals &adjustActuals, bool isSubroutine,
- bool mightBeStructureConstructor) {
+ SymbolVector &&tried,
+ bool mightBeStructureConstructor) -> GenericResolution {
const Symbol &ultimate{symbol.GetUltimate()};
// Check for a match with an explicit INTRINSIC
const Symbol *explicitIntrinsic{nullptr};
@@ -2948,7 +2949,7 @@ std::pair<const Symbol *, bool> ExpressionAnalyzer::ResolveGeneric(
// cannot be unambiguously distinguished
// Underspecified external procedure actual arguments can
// also lead to ambiguity.
- return {nullptr, true /* due to ambiguity */};
+ return {nullptr, true /* due to ambiguity */, std::move(tried)};
}
}
if (!procedure->IsElemental()) {
@@ -2959,6 +2960,8 @@ std::pair<const Symbol *, bool> ExpressionAnalyzer::ResolveGeneric(
}
crtMatchingDistance = ComputeCudaMatchingDistance(
context_.languageFeatures(), *procedure, localActuals);
+ } else {
+ tried.push_back(*specific);
}
}
}
@@ -3038,11 +3041,12 @@ std::pair<const Symbol *, bool> ExpressionAnalyzer::ResolveGeneric(
// Check parent derived type
if (const auto *parentScope{symbol.owner().GetDerivedTypeParent()}) {
if (const Symbol * extended{parentScope->FindComponent(symbol.name())}) {
- auto pair{ResolveGeneric(
- *extended, actuals, adjustActuals, isSubroutine, false)};
- if (pair.first) {
- return pair;
+ auto result{ResolveGeneric(
+ *extended, actuals, adjustActuals, isSubroutine, std::move(tried), false)};
+ if (result.specific != nullptr) {
+ return result;
}
+ tried = std::move(result.tried);
}
}
// Structure constructor?
@@ -3054,14 +3058,15 @@ std::pair<const Symbol *, bool> ExpressionAnalyzer::ResolveGeneric(
if (!symbol.owner().IsGlobal() && !symbol.owner().IsDerivedType()) {
if (const Symbol *
outer{symbol.owner().parent().FindSymbol(symbol.name())}) {
- auto pair{ResolveGeneric(*outer, actuals, adjustActuals, isSubroutine,
- mightBeStructureConstructor)};
- if (pair.first) {
- return pair;
+ auto result{ResolveGeneric(*outer, actuals, adjustActuals, isSubroutine,
+ std::move(tried), mightBeStructureConstructor)};
+ if (result.specific) {
+ return result;
}
+ tried = std::move(result.tried);
}
}
- return {nullptr, false};
+ return {nullptr, false, std::move(tried)};
}
const Symbol &ExpressionAnalyzer::AccessSpecific(
@@ -3098,16 +3103,37 @@ const Symbol &ExpressionAnalyzer::AccessSpecific(
}
}
-void ExpressionAnalyzer::EmitGenericResolutionError(
- const Symbol &symbol, bool dueToAmbiguity, bool isSubroutine) {
- Say(dueToAmbiguity
- ? "The actual arguments to the generic procedure '%s' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface"_err_en_US
- : semantics::IsGenericDefinedOp(symbol)
- ? "No specific procedure of generic operator '%s' matches the actual arguments"_err_en_US
- : isSubroutine
- ? "No specific subroutine of generic '%s' matches the actual arguments"_err_en_US
- : "No specific function of generic '%s' matches the actual arguments"_err_en_US,
- symbol.name());
+void ExpressionAnalyzer::EmitGenericResolutionError(const Symbol &symbol,
+ bool dueToAmbiguity, bool isSubroutine, ActualArguments &arguments,
+ const SymbolVector &tried) {
+ if (auto *msg{Say(dueToAmbiguity
+ ? "The actual arguments to the generic procedure '%s' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface"_err_en_US
+ : semantics::IsGenericDefinedOp(symbol)
+ ? "No specific procedure of generic operator '%s' matches the actual arguments"_err_en_US
+ : isSubroutine
+ ? "No specific subroutine of generic '%s' matches the actual arguments"_err_en_US
+ : "No specific function of generic '%s' matches the actual arguments"_err_en_US,
+ symbol.name())}) {
+ parser::ContextualMessages &messages{GetContextualMessages()};
+ semantics::Scope &scope{context_.FindScope(messages.at())};
+ for (const Symbol &specific : tried) {
+ if (auto procChars{characteristics::Procedure::Characterize(
+ specific, GetFoldingContext())}) {
+ if (auto reasons{semantics::CheckExplicitInterface(*procChars,
+ arguments, context_, &scope, /*intrinsic=*/nullptr,
+ /*allocActualArgumentConversions=*/false,
+ /*extentErrors=*/false,
+ /*ignoreImplicitVsExplicit=*/false)};
+ !reasons.empty()) {
+ reasons.AttachTo(
+ msg->Attach(specific.name(),
+ "Specific procedure '%s' does not match the actual arguments because"_en_US,
+ specific.name()),
+ parser::Severity::None);
+ }
+ }
+ }
+ }
}
auto ExpressionAnalyzer::GetCalleeAndArguments(
@@ -3146,12 +3172,14 @@ auto ExpressionAnalyzer::GetCalleeAndArguments(const parser::Name &name,
bool isGenericInterface{ultimate.has<semantics::GenericDetails>()};
bool isExplicitIntrinsic{ultimate.attrs().test(semantics::Attr::INTRINSIC)};
const Symbol *resolution{nullptr};
+ SymbolVector tried;
if (isGenericInterface || isExplicitIntrinsic) {
ExpressionAnalyzer::AdjustActuals noAdjustment;
- auto pair{ResolveGeneric(*symbol, arguments, noAdjustment, isSubroutine,
- mightBeStructureConstructor)};
- resolution = pair.first;
- dueToAmbiguity = pair.second;
+ auto result{ResolveGeneric(*symbol, arguments, noAdjustment, isSubroutine,
+ SymbolVector{}, mightBeStructureConstructor)};
+ resolution = result.specific;
+ dueToAmbiguity = result.failedDueToAmbiguity;
+ tried = std::move(result.tried);
if (resolution) {
if (context_.GetPPCBuiltinsScope() &&
resolution->name().ToString().rfind("__ppc_", 0) == 0) {
@@ -3182,7 +3210,8 @@ auto ExpressionAnalyzer::GetCalleeAndArguments(const parser::Name &name,
std::move(specificCall->arguments)};
} else {
if (isGenericInterface) {
- EmitGenericResolutionError(*symbol, dueToAmbiguity, isSubroutine);
+ EmitGenericResolutionError(
+ *symbol, dueToAmbiguity, isSubroutine, arguments, tried);
}
return std::nullopt;
}
@@ -4955,8 +4984,7 @@ std::optional<ProcedureRef> ArgumentAnalyzer::GetDefinedAssignmentProc(
auto restorer{context_.GetContextualMessages().DiscardMessages()};
if (const Symbol *symbol{scope.FindSymbol(oprName)}) {
ExpressionAnalyzer::AdjustActuals noAdjustment;
- proc =
- context_.ResolveGeneric(*symbol, actuals_, noAdjustment, true).first;
+proc = context_.ResolveGeneric(*symbol, actuals_, noAdjustment, true, SymbolVector{}).specific;
if (proc) {
isProcElemental = IsElementalProcedure(*proc);
}
@@ -5105,17 +5133,18 @@ const Symbol *ArgumentAnalyzer::FindBoundOp(parser::CharBlock oprName,
[&](const Symbol &proc, ActualArguments &) {
return passIndex == GetPassIndex(proc).value_or(-1);
}};
- auto pair{
- context_.ResolveGeneric(*generic, actuals_, adjustment, isSubroutine)};
- if (const Symbol *binding{pair.first}) {
+ auto result{
+ context_.ResolveGeneric(*generic, actuals_, adjustment, isSubroutine, SymbolVector{})};
+ if (const Symbol *binding{result.specific}) {
CHECK(binding->has<semantics::ProcBindingDetails>());
// Use the most recent override of the binding, if any
return scope->FindComponent(binding->name());
} else {
if (isAmbiguous) {
- *isAmbiguous = pair.second;
+ *isAmbiguous = result.failedDueToAmbiguity;
}
- context_.EmitGenericResolutionError(*generic, pair.second, isSubroutine);
+ context_.EmitGenericResolutionError(
+ *generic, result.failedDueToAmbiguity, isSubroutine, actuals_, result.tried);
}
}
return nullptr;
diff --git a/flang/test/Semantics/generic-error.f90 b/flang/test/Semantics/generic-error.f90
new file mode 100644
index 0000000000000..25c0410a938c5
--- /dev/null
+++ b/flang/test/Semantics/generic-error.f90
@@ -0,0 +1,21 @@
+! RUN: not %flang_fc1 -fsyntax-only %s 2>&1 | FileCheck %s
+module m
+ interface generic
+ procedure :: sub1, sub2
+ end interface
+ contains
+ subroutine sub1(x)
+ end
+ subroutine sub2(j)
+ end
+end
+
+program test
+ use m
+!CHECK: error: No specific subroutine of generic 'generic' matches the actual arguments
+!CHECK: Specific procedure 'sub1' does not match the actual arguments
+!CHECK: Actual argument type 'REAL(8)' is not compatible with dummy argument type 'REAL(4)'
+!CHECK: Specific procedure 'sub2' does not match the actual arguments
+!CHECK: Actual argument type 'REAL(8)' is not compatible with dummy argument type 'INTEGER(4)'
+ call generic(1.d0)
+end
More information about the flang-commits
mailing list