feat(codegen): instantiate function templates by deduction

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

2 files changed, 25 insertions, 2 deletions

diff --git a/include/cps/CodeGen.h b/include/cps/CodeGen.h
index 283c4b1..124ead1 100644
--- a/include/cps/CodeGen.h
+++ b/include/cps/CodeGen.h
@@ -35,9 +35,30 @@ class CodeGen {
     const std::vector<SourceUnit> *Units = nullptr;
     size_t CurrentUnit = 0;
     size_t MainUnit = 0;
+    std::optional<size_t> VisibilityUnit;
     IdentifierMap<size_t> TypeOwners;
     struct TemplateDefinition { TemplateDeclAST *Decl; size_t OwnerUnit; };
     IdentifierMap<std::vector<TemplateDefinition>> Templates;
+    struct TemplateInstance {
+        TemplateDeclAST *Decl;
+        std::string Arguments;
+        std::unique_ptr<FunctionDefAST> Function;
+        const FuncSig *Signature;
+        size_t OwnerUnit;
+        size_t RequesterUnit;
+        unsigned Depth;
+    };
+    std::vector<TemplateInstance> TemplateInstances;
+    std::map<const TemplateDeclAST *, IdentifierMap<SymbolInfo>> TemplateSymbols;
+    size_t NextTemplateBody = 0;
+    unsigned TemplateDepth = 0;
+    bool hasCallable(const std::string &Name) const;
+    bool hasFunctionTemplate(const std::string &Name) const;
+    void validateTemplates();
+    void captureTemplateSymbols();
+    const FuncSig *instantiateFunction(const TemplateDefinition &Definition,
+        const IdentifierMap<std::vector<std::string>> &Bindings);
+    void drainTemplateBodies();
     std::vector<IdentifierMap<SymbolInfo>> Exports;
     bool isVisible(size_t Owner) const;
     void selectUnit(size_t Unit);
diff --git a/include/cps/FunctionGen.h b/include/cps/FunctionGen.h
index 57a27ff..a50e70b 100644
--- a/include/cps/FunctionGen.h
+++ b/include/cps/FunctionGen.h
@@ -5,6 +5,7 @@
 #include "cps/FunctionAST.h"
 #include "cps/TypeSystem.h"
 #include <cstdint>
+#include <deque>
 #include <map>
 #include <utility>
 #include <vector>
@@ -73,7 +74,7 @@ private:
     int &DiagnosticLine;
     void reportError(const char *Fmt, ...);
 
-    IdentifierMap<std::vector<FuncSig>> Signatures;
+    IdentifierMap<std::deque<FuncSig>> Signatures;
     IdentifierMap<std::pair<std::string, size_t>> LinkIndex;
     std::map<const PrototypeAST *, std::string> PrototypeLinks;
     std::map<size_t, std::string> UnitPaths;
@@ -106,7 +107,8 @@ public:
     void setCurrentUnit(size_t Unit, const std::string &Path) { CurrentUnit = Unit; UnitPaths[Unit] = Path; }
     void setCallHook(std::function<void(const FuncSig &)> Hook) { BeforeCall = std::move(Hook); }
     void setVisibility(std::function<bool(size_t)> Predicate) { Visible = std::move(Predicate); }
-    std::vector<const FuncSig *> getOverloads(const std::string &Name) const;
+    std::vector<const FuncSig *> getOverloads(const std::string &Name, bool AllUnits = false) const;
+    static bool isReservedRuntimeName(const std::string &Name);
     bool hasFunction(const std::string &Name) const { return !getOverloads(Name).empty(); }
     const FuncSig *getSignatureByLink(const std::string &Name) const;