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[Macros] Enable freestanding macros at module scope in script mode

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Eliminate the error message

    error: global freestanding macros not yet supported in script mode

by implementing name lookup, type checking, and code emission for
freestanding macros. The key problem here is that, in script mode,
it is ambiguous whether a use of a freestanding macro is an expression
or a declaration. We parse as an expression (as we do within a
function body), which then gets wrapped in a top-level code
declaration.

Teach various parts of the compiler to look through a top-level code
declaration wrapping a macro expansion expression that is for a
declaration or code-item macro, e.g., by recording these for global
name lookup and treating their expansions as "auxiliary" declarations.

Fixes rdar://109699501.
This commit is contained in:
Doug Gregor
2023-07-03 21:00:51 -07:00
parent 6fca08acf7
commit 939376b61e
8 changed files with 207 additions and 76 deletions
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174
lib/AST/Module.cpp
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@@ -179,9 +179,9 @@ class swift::SourceLookupCache {
/// Top-level macros that produce arbitrary names.
SmallVector<MissingDecl *, 4> TopLevelArbitraryMacros;
SmallVector<Decl *, 4> MayHaveAuxiliaryDecls;
SmallVector<llvm::PointerUnion<Decl *, MacroExpansionExpr *>, 4>
MayHaveAuxiliaryDecls;
void populateAuxiliaryDeclCache();
SourceLookupCache(ASTContext &ctx);
public:
@@ -238,10 +238,30 @@ SourceLookupCache &SourceFile::getCache() const {
return *Cache;
}
static Expr *getAsExpr(Decl *decl) { return nullptr; }
static Decl *getAsDecl(Decl *decl) { return decl; }
static Expr *getAsExpr(ASTNode node) { return node.dyn_cast<Expr *>(); }
static Decl *getAsDecl(ASTNode node) { return node.dyn_cast<Decl *>(); }
template<typename Range>
void SourceLookupCache::addToUnqualifiedLookupCache(Range decls,
void SourceLookupCache::addToUnqualifiedLookupCache(Range items,
bool onlyOperators) {
for (Decl *D : decls) {
for (auto item : items) {
// In script mode, we'll see macro expansion expressions for freestanding
// macros.
if (Expr *E = getAsExpr(item)) {
if (auto MEE = dyn_cast<MacroExpansionExpr>(E)) {
if (!onlyOperators)
MayHaveAuxiliaryDecls.push_back(MEE);
}
continue;
}
Decl *D = getAsDecl(item);
if (!D)
continue;
if (auto *VD = dyn_cast<ValueDecl>(D)) {
if (onlyOperators ? VD->isOperator() : VD->hasName()) {
// Cache the value under both its compound name and its full name.
@@ -280,6 +300,10 @@ void SourceLookupCache::addToUnqualifiedLookupCache(Range decls,
else if (auto *MED = dyn_cast<MacroExpansionDecl>(D)) {
if (!onlyOperators)
MayHaveAuxiliaryDecls.push_back(MED);
} else if (auto TLCD = dyn_cast<TopLevelCodeDecl>(D)) {
if (auto body = TLCD->getBody()){
addToUnqualifiedLookupCache(body->getElements(), onlyOperators);
}
}
}
}
@@ -335,75 +359,113 @@ void SourceLookupCache::addToMemberCache(Range decls) {
}
void SourceLookupCache::populateAuxiliaryDeclCache() {
using MacroRef = llvm::PointerUnion<MacroExpansionDecl *, CustomAttr *>;
for (auto *decl : MayHaveAuxiliaryDecls) {
using MacroRef = llvm::PointerUnion<FreestandingMacroExpansion *, CustomAttr *>;
for (auto item : MayHaveAuxiliaryDecls) {
TopLevelCodeDecl *topLevelCodeDecl = nullptr;
// Gather macro-introduced peer names.
llvm::SmallDenseMap<MacroRef, llvm::SmallVector<DeclName, 2>>
introducedNames;
// This code deliberately avoids `forEachAttachedMacro`, because it
// will perform overload resolution and possibly invoke unqualified
// lookup for macro arguments, which will recursively populate the
// auxiliary decl cache and cause request cycles.
//
// We do not need a fully resolved macro until expansion. Instead, we
// conservatively consider peer names for all macro declarations with a
// custom attribute name. Unqualified lookup for that name will later
// invoke expansion of the macro, and will yield no results if the resolved
// macro does not produce the requested name, so the only impact is possibly
// expanding earlier than needed / unnecessarily looking in the top-level
// auxiliary decl cache.
for (auto attrConst : decl->getAttrs().getAttributes<CustomAttr>()) {
auto *attr = const_cast<CustomAttr *>(attrConst);
UnresolvedMacroReference macroRef(attr);
bool introducesArbitraryNames = false;
namelookup::forEachPotentialResolvedMacro(
decl->getDeclContext()->getModuleScopeContext(),
macroRef.getMacroName(), MacroRole::Peer,
[&](MacroDecl *macro, const MacroRoleAttr *roleAttr) {
// First check for arbitrary names.
if (roleAttr->hasNameKind(MacroIntroducedDeclNameKind::Arbitrary)) {
introducesArbitraryNames = true;
}
/// Introduce names for a freestanding macro.
auto introduceNamesForFreestandingMacro =
[&](FreestandingMacroExpansion *macroRef, Decl *decl, MacroRole role) {
bool introducesArbitraryNames = false;
namelookup::forEachPotentialResolvedMacro(
decl->getDeclContext()->getModuleScopeContext(),
macroRef->getMacroName(), role,
[&](MacroDecl *macro, const MacroRoleAttr *roleAttr) {
// First check for arbitrary names.
if (roleAttr->hasNameKind(MacroIntroducedDeclNameKind::Arbitrary)) {
introducesArbitraryNames = true;
}
macro->getIntroducedNames(MacroRole::Peer,
dyn_cast<ValueDecl>(decl),
introducedNames[attr]);
});
macro->getIntroducedNames(role,
/*attachedTo*/ nullptr,
introducedNames[macroRef]);
});
// Record this macro where appropriate.
if (introducesArbitraryNames)
TopLevelArbitraryMacros.push_back(MissingDecl::forUnexpandedMacro(attr, decl));
return introducesArbitraryNames;
};
// Handle macro expansion expressions, which show up in when we have
// freestanding macros in "script" mode.
if (auto expr = item.dyn_cast<MacroExpansionExpr *>()) {
topLevelCodeDecl = dyn_cast<TopLevelCodeDecl>(expr->getDeclContext());
if (topLevelCodeDecl) {
bool introducesArbitraryNames = false;
if (introduceNamesForFreestandingMacro(
expr, topLevelCodeDecl, MacroRole::Declaration))
introducesArbitraryNames = true;
if (introduceNamesForFreestandingMacro(
expr, topLevelCodeDecl, MacroRole::CodeItem))
introducesArbitraryNames = true;
// Record this macro if it introduces arbitrary names.
if (introducesArbitraryNames) {
TopLevelArbitraryMacros.push_back(
MissingDecl::forUnexpandedMacro(expr, topLevelCodeDecl));
}
}
}
if (auto *med = dyn_cast<MacroExpansionDecl>(decl)) {
UnresolvedMacroReference macroRef(med);
bool introducesArbitraryNames = false;
namelookup::forEachPotentialResolvedMacro(
decl->getDeclContext()->getModuleScopeContext(),
macroRef.getMacroName(), MacroRole::Declaration,
[&](MacroDecl *macro, const MacroRoleAttr *roleAttr) {
// First check for arbitrary names.
if (roleAttr->hasNameKind(MacroIntroducedDeclNameKind::Arbitrary)) {
introducesArbitraryNames = true;
}
auto *decl = item.dyn_cast<Decl *>();
if (decl) {
// This code deliberately avoids `forEachAttachedMacro`, because it
// will perform overload resolution and possibly invoke unqualified
// lookup for macro arguments, which will recursively populate the
// auxiliary decl cache and cause request cycles.
//
// We do not need a fully resolved macro until expansion. Instead, we
// conservatively consider peer names for all macro declarations with a
// custom attribute name. Unqualified lookup for that name will later
// invoke expansion of the macro, and will yield no results if the resolved
// macro does not produce the requested name, so the only impact is possibly
// expanding earlier than needed / unnecessarily looking in the top-level
// auxiliary decl cache.
for (auto attrConst : decl->getAttrs().getAttributes<CustomAttr>()) {
auto *attr = const_cast<CustomAttr *>(attrConst);
UnresolvedMacroReference macroRef(attr);
bool introducesArbitraryNames = false;
namelookup::forEachPotentialResolvedMacro(
decl->getDeclContext()->getModuleScopeContext(),
macroRef.getMacroName(), MacroRole::Peer,
[&](MacroDecl *macro, const MacroRoleAttr *roleAttr) {
// First check for arbitrary names.
if (roleAttr->hasNameKind(
MacroIntroducedDeclNameKind::Arbitrary)) {
introducesArbitraryNames = true;
}
macro->getIntroducedNames(MacroRole::Declaration,
/*attachedTo*/ nullptr,
introducedNames[med]);
});
macro->getIntroducedNames(MacroRole::Peer,
dyn_cast<ValueDecl>(decl),
introducedNames[attr]);
});
// Record this macro where appropriate.
// Record this macro where appropriate.
if (introducesArbitraryNames)
TopLevelArbitraryMacros.push_back(
MissingDecl::forUnexpandedMacro(attr, decl));
}
}
if (auto *med = dyn_cast_or_null<MacroExpansionDecl>(decl)) {
bool introducesArbitraryNames =
introduceNamesForFreestandingMacro(med, decl, MacroRole::Declaration);
// Note whether this macro produces arbitrary names.
if (introducesArbitraryNames)
TopLevelArbitraryMacros.push_back(MissingDecl::forUnexpandedMacro(med, decl));
}
// Add macro-introduced names to the top-level auxiliary decl cache as
// unexpanded decls represented by a MissingDecl.
auto anchorDecl = decl ? decl : topLevelCodeDecl;
for (auto macroNames : introducedNames) {
auto macroRef = macroNames.getFirst();
for (auto name : macroNames.getSecond()) {
auto *placeholder = MissingDecl::forUnexpandedMacro(macroRef, decl);
auto *placeholder = MissingDecl::forUnexpandedMacro(macroRef, anchorDecl);
name.addToLookupTable(TopLevelAuxiliaryDecls, placeholder);
}
}
@@ -421,7 +483,7 @@ SourceLookupCache::SourceLookupCache(const SourceFile &SF)
{
FrontendStatsTracer tracer(SF.getASTContext().Stats,
"source-file-populate-cache");
addToUnqualifiedLookupCache(SF.getTopLevelDecls(), false);
addToUnqualifiedLookupCache(SF.getTopLevelItems(), false);
addToUnqualifiedLookupCache(SF.getHoistedDecls(), false);
}
@@ -432,7 +494,7 @@ SourceLookupCache::SourceLookupCache(const ModuleDecl &M)
"module-populate-cache");
for (const FileUnit *file : M.getFiles()) {
auto *SF = cast<SourceFile>(file);
addToUnqualifiedLookupCache(SF->getTopLevelDecls(), false);
addToUnqualifiedLookupCache(SF->getTopLevelItems(), false);
addToUnqualifiedLookupCache(SF->getHoistedDecls(), false);
if (auto *SFU = file->getSynthesizedFile()) {