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[clang][Modules] Permit Link Declarations in Submodule Declarations in Module Maps #156377

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[clang][Modules] Permit Link Declarations in Submodule Declarations in Module Maps #156377

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0cb749e
Permit link decls in submodule declarations.
qiongsiwu Sep 1, 2025
54ec813
Merge branch 'main' into eng_159467837_01
qiongsiwu Sep 2, 2025
4b36ae5
Remove the check against link decls in submodules.
qiongsiwu Sep 2, 2025
7a32977
Remove incorrect comment.
qiongsiwu Sep 3, 2025
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2 changes: 0 additions & 2 deletions clang/include/clang/Basic/DiagnosticLexKinds.td
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Original file line number Diff line number Diff line change
Expand Up @@ -915,8 +915,6 @@ def err_mmap_expected_attribute : Error<"expected an attribute name">;
def warn_mmap_link_redeclaration : Warning<"redeclaration of link library '%0'">,
InGroup<DiagGroup<"module-link-redeclaration">>, DefaultError;
def note_mmap_prev_link_declaration : Note<"previously declared here">;
def err_mmap_submodule_link_decl
: Error<"link declaration is not allowed in submodules">;
def warn_mmap_unknown_attribute : Warning<"unknown attribute '%0'">,
InGroup<IgnoredAttributes>;
def warn_mmap_mismatched_private_submodule : Warning<
Expand Down
18 changes: 4 additions & 14 deletions clang/lib/Lex/ModuleMapFile.cpp
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Expand Up @@ -119,7 +119,7 @@ struct ModuleMapFileParser {
std::optional<UmbrellaDirDecl>
parseUmbrellaDirDecl(SourceLocation UmbrellaLoc);
std::optional<LinkDecl>
parseLinkDecl(llvm::StringMap<SourceLocation> &SeenLinkDecl, bool Allowed);
parseLinkDecl(llvm::StringMap<SourceLocation> &SeenLinkDecl);

SourceLocation consumeToken();
void skipUntil(MMToken::TokenKind K);
Expand Down Expand Up @@ -407,9 +407,7 @@ std::optional<ModuleDecl> ModuleMapFileParser::parseModuleDecl(bool TopLevel) {
break;

case MMToken::LinkKeyword:
// Link decls are only allowed in top level modules or explicit
// submodules.
SubDecl = parseLinkDecl(SeenLinkDecl, TopLevel || MDecl.Explicit);
SubDecl = parseLinkDecl(SeenLinkDecl);
break;

default:
Expand Down Expand Up @@ -827,7 +825,7 @@ ModuleMapFileParser::parseUmbrellaDirDecl(clang::SourceLocation UmbrellaLoc) {
/// module-declaration:
/// 'link' 'framework'[opt] string-literal
std::optional<LinkDecl> ModuleMapFileParser::parseLinkDecl(
llvm::StringMap<SourceLocation> &SeenLinkDecl, bool Allowed) {
llvm::StringMap<SourceLocation> &SeenLinkDecl) {
assert(Tok.is(MMToken::LinkKeyword));
LinkDecl LD;
LD.Location = consumeToken();
Expand All @@ -853,21 +851,13 @@ std::optional<LinkDecl> ModuleMapFileParser::parseLinkDecl(
LD.Library = Library;
consumeToken();

// Make sure we eat all the tokens when we report the errors so parsing
// Make sure we eat all the token when we report the errors so parsing
// can continue.
if (!Allowed) {
Diags.Report(LD.Location, diag::err_mmap_submodule_link_decl);
HadError = true;
return std::nullopt;
}

auto [It, Inserted] =
SeenLinkDecl.insert(std::make_pair(Library, LD.Location));
if (!Inserted) {
Diags.Report(LD.Location, diag::warn_mmap_link_redeclaration) << Library;
Diags.Report(It->second, diag::note_mmap_prev_link_declaration);
HadError = true;
return std::nullopt;
}

return std::move(LD);
Expand Down
15 changes: 9 additions & 6 deletions clang/test/ClangScanDeps/link-libraries-diag-dup.c
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Expand Up @@ -14,8 +14,10 @@ module A {
explicit module D {
header "D.h"
link "libraryD"
link "libraryD"
}

link "libraryB"
link "libraryA"
link "libraryA"
}
Expand Down Expand Up @@ -49,9 +51,10 @@ module C {
// RUN: not clang-scan-deps -compilation-database %t/cdb.json -format \
// RUN: experimental-full 2>&1 | FileCheck %s

// Note that module D does not report an error because it is explicit.
// Therefore we can use CHECK-NEXT for the redeclaration error on line 15.
// CHECK: module.modulemap:6:5: error: link declaration is not allowed in submodules
// CHECK-NEXT: module.modulemap:15:3: error: redeclaration of link library 'libraryA' [-Wmodule-link-redeclaration]
// CHECK-NEXT: module.modulemap:14:3: note: previously declared here
// CHECK-NOT: module.modulemap:20:3: error: redeclaration of link library 'libraryA'
// Note that the `link "libraryB"` in the top level module A does not
// cause an issue because we only check within a module.
// CHECK: 12:5: error: redeclaration of link library 'libraryD' [-Wmodule-link-redeclaration]
// CHECK-NEXT: 11:5: note: previously declared here
// CHECK-NEXT: 17:3: error: redeclaration of link library 'libraryA' [-Wmodule-link-redeclaration]
// CHECK-NEXT: 16:3: note: previously declared here
// CHECK-NOT: error: redeclaration of link library 'libraryB'