feat(library)!: replace #LIB with __LIB source regions

Track library mode by original source line, including deferred template bodies
and automatic object cleanup. Update call lines from ordinary code and migrate
the embedded standard library to PP_DEFINE __LIB.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

21 files changed, 115 insertions, 25 deletions

diff --git a/include/cps/CodeGen.h b/include/cps/CodeGen.h
index 0962753..c3a7b19 100644
--- a/include/cps/CodeGen.h
+++ b/include/cps/CodeGen.h
@@ -106,6 +106,7 @@ class CodeGen {
         llvm::AllocaInst *Alive;
         llvm::AllocaInst *Count; // Non-null for an array; Addr then holds its buffer pointer.
         int Line;
+        size_t OwnerUnit;
         bool Temporary = false;
     };
     std::vector<StackObject> StackObjects;
diff --git a/include/cps/Lexer.h b/include/cps/Lexer.h
index 05fb857..3d057a3 100644
--- a/include/cps/Lexer.h
+++ b/include/cps/Lexer.h
@@ -128,7 +128,6 @@ class Lexer {
     int CurrentLine = 1;
     int TokenLine = 1;
     bool HadError = false;
-    bool Library = false;
     bool LineStart = true;
     struct TokenData {
         int Kind, Line;
@@ -158,7 +157,6 @@ public:
     int peekToken(unsigned Offset = 0);
     int peekLine(unsigned Offset = 0);
     int getLine() const { return TokenLine; }
-    bool isLibrary() const { return Library; }
     bool hadError() const { return HadError; }
     // Human-readable spelling of Tok for diagnostics; Lex supplies identifier text.
     static std::string tokenSpelling(int Tok, const Lexer &Lex);
diff --git a/include/cps/RuntimeCheck.h b/include/cps/RuntimeCheck.h
index d2ee1ea..71943d4 100644
--- a/include/cps/RuntimeCheck.h
+++ b/include/cps/RuntimeCheck.h
@@ -3,6 +3,8 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include <cstdint>
+#include <functional>
+#include <utility>
 #include <string>
 
 namespace cps {
@@ -18,7 +20,7 @@ class RuntimeCheck {
     llvm::FunctionCallee StderrFunc;   // Windows: __acrt_iob_func(2)
     llvm::GlobalVariable *StderrVar;   // elsewhere: the C library's stderr
     ExceptionHandler &Exceptions;
-    bool LibraryMode = false;
+    std::function<bool(int)> LibraryLookup;
     llvm::GlobalVariable *UserLine;
     llvm::Value *DivZeroMsg;
     llvm::Value *OutOfBoundsMsg;
@@ -33,7 +35,7 @@ public:
     RuntimeCheck(llvm::Module &M, llvm::LLVMContext &C, llvm::IRBuilder<> &B,
                  ExceptionHandler &EH);
 
-    void setLibraryMode(bool Enabled) { LibraryMode = Enabled; }
+    void setLibraryLookup(std::function<bool(int)> Lookup) { LibraryLookup = std::move(Lookup); }
     llvm::Value *lineValue(int Line);
     void setUserLine(int Line);
 
diff --git a/include/cps/SourceUnit.h b/include/cps/SourceUnit.h
index 34266ac..153d020 100644
--- a/include/cps/SourceUnit.h
+++ b/include/cps/SourceUnit.h
@@ -9,6 +9,9 @@ struct SourceUnit {
     std::string Path;
     const std::vector<std::unique_ptr<StmtAST>> &Statements;
     std::vector<bool> Visible;
-    bool IsLibrary = false;
+    std::vector<bool> LibraryLines;
+    bool isLibrary(int Line) const {
+        return Line > 0 && static_cast<size_t>(Line) <= LibraryLines.size() && LibraryLines[Line - 1];
+    }
 };
 }
diff --git a/lib/CodeGen/CodeGen.cc b/lib/CodeGen/CodeGen.cc
index 49b470c..ce5fa00 100644
--- a/lib/CodeGen/CodeGen.cc
+++ b/lib/CodeGen/CodeGen.cc
@@ -149,9 +149,12 @@ void CodeGen::selectUnit(size_t Unit) {
     CurrentUnit = Unit;
     DiagnosticSource = (*Units)[Unit].Path;
     FuncGen->setCurrentUnit(Unit, (*Units)[Unit].Path);
-    RuntimeChecker->setLibraryMode((*Units)[Unit].IsLibrary);
-    FuncGen->setCallHook([this](const FuncSig &Sig) {
-        if (!(*Units)[CurrentUnit].IsLibrary && (*Units)[Sig.OwnerUnit].IsLibrary)
+    RuntimeChecker->setLibraryLookup([this](int Line) {
+        return (*Units)[CurrentUnit].isLibrary(Line);
+    });
+    FuncGen->setCallHook([this](const FuncSig &) {
+        // The callee may enable __LIB inside its body even if its header is ordinary code.
+        if (!(*Units)[CurrentUnit].isLibrary(DiagnosticLine))
             RuntimeChecker->setUserLine(DiagnosticLine);
     });
 }
@@ -195,7 +198,8 @@ void CodeGen::compile(const std::vector<SourceUnit> &Sources) {
         if (!Added && !Compatible && (It->second.Unit != CurrentUnit ||
             ((IsTemplate || It->second.IsTemplate) && !(IsFunction && It->second.IsFunction)))) {
             // Default library units follow user inputs; point at the user's conflicting definition.
-            bool UserConflict = Sources[CurrentUnit].IsLibrary && !Sources[It->second.Unit].IsLibrary;
+            bool UserConflict = Sources[CurrentUnit].isLibrary(DiagnosticLine) &&
+                                !Sources[It->second.Unit].isLibrary(It->second.Line);
             SaveAndRestore<int> Location(DiagnosticLine, UserConflict ? It->second.Line : DiagnosticLine);
             SaveAndRestore<std::string> Source(DiagnosticSource,
                 UserConflict ? Sources[It->second.Unit].Path : DiagnosticSource);
diff --git a/lib/CodeGen/ConstructorGen.cc b/lib/CodeGen/ConstructorGen.cc
index b029385..da89f59 100644
--- a/lib/CodeGen/ConstructorGen.cc
+++ b/lib/CodeGen/ConstructorGen.cc
@@ -284,7 +284,7 @@ size_t CodeGen::registerStackObject(Value *Addr, const std::string &TypeName, in
         Count = Entry.CreateAlloca(Entry.getInt64Ty(), nullptr, "object_count");
         Entry.CreateStore(Entry.getInt64(0), Count);
     }
-    StackObjects.push_back({Addr, TypeName, Alive, Count, Line});
+    StackObjects.push_back({Addr, TypeName, Alive, Count, Line, CurrentUnit});
     // This DECLARE can execute repeatedly, including after a backward loop edge.
     emitStackObjectCleanup(StackObjects.back());
     return StackObjects.size() - 1;
@@ -298,6 +298,8 @@ void CodeGen::activateStackObject(size_t Index, Value *Count) {
 }
 
 void CodeGen::emitStackObjectCleanup(const StackObject &Object) {
+    size_t SavedUnit = CurrentUnit;
+    selectUnit(Object.OwnerUnit);
     auto *F = Builder->GetInsertBlock()->getParent();
     auto *Destroy = BasicBlock::Create(*TheContext, "destroy_object", F);
     auto *Done = BasicBlock::Create(*TheContext, "destroyed_object", F);
@@ -339,6 +341,7 @@ void CodeGen::emitStackObjectCleanup(const StackObject &Object) {
     }
     Builder->CreateBr(Done);
     Builder->SetInsertPoint(Done);
+    selectUnit(SavedUnit);
 }
 
 void CodeGen::finishStackObjects(Function *F) {
diff --git a/lib/CodeGen/RuntimeCheck.cc b/lib/CodeGen/RuntimeCheck.cc
index e15c10b..3991bf2 100644
--- a/lib/CodeGen/RuntimeCheck.cc
+++ b/lib/CodeGen/RuntimeCheck.cc
@@ -17,8 +17,9 @@ RuntimeCheck::RuntimeCheck(Module &M, LLVMContext &C, IRBuilder<> &B, ExceptionH
 }
 
 Value *RuntimeCheck::lineValue(int Line) {
-    return LibraryMode ? Builder.CreateLoad(Builder.getInt32Ty(), UserLine, "user_line")
-                       : static_cast<Value *>(Builder.getInt32(Line));
+    return LibraryLookup && LibraryLookup(Line)
+        ? Builder.CreateLoad(Builder.getInt32Ty(), UserLine, "user_line")
+        : static_cast<Value *>(Builder.getInt32(Line));
 }
 
 void RuntimeCheck::setUserLine(int Line) {
diff --git a/lib/Lexer/Lexer.cc b/lib/Lexer/Lexer.cc
index 5bf2230..40bfce3 100644
--- a/lib/Lexer/Lexer.cc
+++ b/lib/Lexer/Lexer.cc
@@ -220,17 +220,10 @@ int Lexer::readToken() {
 
     TokenLine = CurrentLine;
     if (LastChar == '#' && LineStart) {
-        std::string Directive;
         do {
-            Directive += static_cast<char>(LastChar);
             LastChar = Input.get();
         } while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
-        while (!Directive.empty() && isspace(static_cast<unsigned char>(Directive.back())))
-            Directive.pop_back();
-        if (Directive == "#LIB") Library = true;
-        else {
-            reportError(TokenLine, "Unknown compiler directive");
-        }
+        reportError(TokenLine, "Unknown compiler directive");
         return readToken();
     }
     LineStart = false;
diff --git a/pseudocode-lib/memory.cps b/pseudocode-lib/memory.cps
index 26287c3..b02ca2a 100644
--- a/pseudocode-lib/memory.cps
+++ b/pseudocode-lib/memory.cps
@@ -1,4 +1,4 @@
-#LIB
+PP_DEFINE __LIB
 INCLUDE_OBJ "memory.o"
 TYPE _MEMORY_ADDRESS = C_TYPE("void*")
 TYPE _MEMORY_SIZE = C_TYPE("unsigned long long")
diff --git a/pseudocode-lib/std.cps b/pseudocode-lib/std.cps
index 6068bd0..6aa411b 100644
--- a/pseudocode-lib/std.cps
+++ b/pseudocode-lib/std.cps
@@ -1,3 +1,3 @@
-#LIB
+PP_DEFINE __LIB
 INCLUDE "string.cps"
 INCLUDE "memory.cps"
diff --git a/pseudocode-lib/string.cps b/pseudocode-lib/string.cps
index cb06758..135f5d7 100644
--- a/pseudocode-lib/string.cps
+++ b/pseudocode-lib/string.cps
@@ -1,4 +1,4 @@
-#LIB
+PP_DEFINE __LIB
 INCLUDE_OBJ "string.o"
 TYPE _STRING_HANDLE = C_TYPE("void*")
 TYPE _STRING_C_INTEGER = C_TYPE("long long")
diff --git a/tests/i/library-lines/library.cps b/tests/i/library-lines/library.cps
index a35a2e9..d54f948 100644
--- a/tests/i/library-lines/library.cps
+++ b/tests/i/library-lines/library.cps
@@ -1,4 +1,4 @@
-#LIB
+PP_DEFINE __LIB
 PROCEDURE Check()
     CALL Inner()
 ENDPROCEDURE
diff --git a/tests/i/library-regions/case.json b/tests/i/library-regions/case.json
new file mode 100644
index 0000000..9f95525
--- /dev/null
+++ b/tests/i/library-regions/case.json
@@ -0,0 +1,6 @@
+{
+  "sources": [
+    "program.cps",
+    "regions.cps"
+  ]
+}
diff --git a/tests/i/library-regions/expected-stderr.txt b/tests/i/library-regions/expected-stderr.txt
new file mode 100644
index 0000000..89aee0f
--- /dev/null
+++ b/tests/i/library-regions/expected-stderr.txt
@@ -0,0 +1,6 @@
+[Fatal] line 2: Division by zero
+[Fatal] line 10: Division by zero
+[Fatal] line 15: Division by zero
+[Fatal] line 23: Division by zero
+[Fatal] line 4: Division by zero
+[Fatal] line 9: Division by zero
diff --git a/tests/i/library-regions/expected.txt b/tests/i/library-regions/expected.txt
new file mode 100644
index 0000000..b414108
--- /dev/null
+++ b/tests/i/library-regions/expected.txt
@@ -0,0 +1,6 @@
+1
+2
+3
+4
+5
+6
diff --git a/tests/i/library-regions/notes.md b/tests/i/library-regions/notes.md
new file mode 100644
index 0000000..dbe4faf
--- /dev/null
+++ b/tests/i/library-regions/notes.md
@@ -0,0 +1,5 @@
+# Trace notes
+
+Review status: pending human review.
+
+Mixed has an ordinary header but enables __LIB inside its body. Its first division uses the caller's line 2. After UNDEF, its own division uses regions.cps line 10 and a nested library call uses line 15. A disabled DEFINE does not enable __LIB, so the next division uses line 23. The library template retains its definition's mode during deferred emission and reports its caller's line 4. DeleteOnExit destroys its local object on return; the automatic library destructor retains the ordinary caller's line 9. Every error is caught and prints the next integer from 1 through 6. These are compiler extensions.
diff --git a/tests/i/library-regions/program.cps b/tests/i/library-regions/program.cps
new file mode 100644
index 0000000..315dbe6
--- /dev/null
+++ b/tests/i/library-regions/program.cps
@@ -0,0 +1,12 @@
+INCLUDE "regions.cps"
+CALL Mixed()
+TRY
+    CALL TemplateError<INTEGER>()
+CATCH
+    OUTPUT 5
+ENDTRY
+TRY
+    CALL DeleteOnExit()
+CATCH
+    OUTPUT 6
+ENDTRY
diff --git a/tests/i/library-regions/regions.cps b/tests/i/library-regions/regions.cps
new file mode 100644
index 0000000..310014a
--- /dev/null
+++ b/tests/i/library-regions/regions.cps
@@ -0,0 +1,47 @@
+PROCEDURE Mixed()
+PP_DEFINE __LIB
+TRY
+    OUTPUT 1 DIV 0
+CATCH
+    OUTPUT 1
+ENDTRY
+PP_UNDEF __LIB
+TRY
+    OUTPUT 1 DIV 0
+CATCH
+    OUTPUT 2
+ENDTRY
+TRY
+    CALL LibraryError()
+CATCH
+    OUTPUT 3
+ENDTRY
+PP_IFDEF Never
+PP_DEFINE __LIB
+PP_ENDIF
+TRY
+    OUTPUT 1 DIV 0
+CATCH
+    OUTPUT 4
+ENDTRY
+ENDPROCEDURE
+PP_DEFINE __LIB
+PROCEDURE LibraryError()
+    CALL NestedError()
+ENDPROCEDURE
+PROCEDURE NestedError()
+    OUTPUT 1 DIV 0
+ENDPROCEDURE
+TEMPLATE <T>
+PROCEDURE TemplateError()
+    OUTPUT 1 DIV 0
+ENDPROCEDURE
+CLASS DeleteError
+    PROCEDURE DELETE()
+        OUTPUT 1 DIV 0
+    ENDPROCEDURE
+ENDCLASS
+PROCEDURE DeleteOnExit()
+    DECLARE X : DeleteError
+ENDPROCEDURE
+PP_UNDEF __LIB
diff --git a/tests/iii/legacy-lib/case.json b/tests/iii/legacy-lib/case.json
new file mode 100644
index 0000000..d593f34
--- /dev/null
+++ b/tests/iii/legacy-lib/case.json
@@ -0,0 +1 @@
+{"errors":[{"reason":"Unknown compiler directive","line":1}]}
diff --git a/tests/iii/legacy-lib/program.cps b/tests/iii/legacy-lib/program.cps
new file mode 100644
index 0000000..8abe9d9
--- /dev/null
+++ b/tests/iii/legacy-lib/program.cps
@@ -0,0 +1,2 @@
+#LIB
+OUTPUT 1
diff --git a/tools/driver/main.cc b/tools/driver/main.cc
index e3d4c28..d0e7c07 100644
--- a/tools/driver/main.cc
+++ b/tools/driver/main.cc
@@ -200,7 +200,7 @@ bool parseUnits(const std::vector<std::string> &InputPaths, size_t UserInputCoun
         cps::Parser Parser(Lex);
         Programs[I] = Parser.Parse();
         if (Lex.hadError() || Parser.hadError()) return false;
-        Units.push_back({InputPath, Programs[I], std::vector<bool>(InputPaths.size(), false), Lex.isLibrary()});
+        Units.push_back({InputPath, Programs[I], std::vector<bool>(InputPaths.size(), false), std::move(Source.LibraryLines)});
         Units.back().Visible[I] = true;
         if (!NoStd && I < UserInputCount)
             for (size_t J = UserInputCount; J < InputPaths.size(); ++J)