c2lang · chqrlie · Jan 14, 2026
diff --git a/analyser/conversion_checker_expr.c2 b/analyser/conversion_checker_expr.c2
@@ -64,6 +64,7 @@ fn ExprWidth getExprWidth(const Expr* e) {
         return getTypeWidth(e.getType());
     case Type:
         break;
+    case Template:
     case Call:
         return getTypeWidth(e.getType());
     case InitList:

diff --git a/analyser/module_analyser_call.c2 b/analyser/module_analyser_call.c2
@@ -29,6 +29,31 @@ const char[] DiagTooManyArgs = "too many arguments to %sfunction call, expected
 const char[] DiagTooFewArgs = "too few arguments to %sfunction call, expected %d, have %d";
 const char[] NoteDeclaredHere = "'%s' is defined here";
 
+fn QualType Analyser.analyseTemplateExpr(Analyser* ma, Expr** e_ptr) {
+    Expr* e = *e_ptr;
+    TemplateExpr* tp = (TemplateExpr*)e;
+    Expr** func = tp.getFunc2();
+    Expr* origFn = tp.getFunc();  // store here to avoid the likely inserted FunctionPointerDecay cast
+    QualType qt = ma.analyseExpr(func, true, RHS);
+    if (qt.isInvalid()) return QualType_Invalid;
+    FunctionType* ft = qt.getFunctionTypeOrNil();
+    if (!ft) {
+        ma.errorRange(origFn.getLoc(), origFn.getRange(), "object type %s is not a function template", qt.diagName());
+        return QualType_Invalid;
+    }
+    FunctionDecl* fd = ft.getDecl();
+    if (!fd.isTemplate() || fd.isTemplateTypeFunction()) {
+        ma.errorRange(e.getLoc(), e.getRange(), "function %s is not a template function", fd.asDecl().getFullName());
+        return QualType_Invalid;
+    }
+
+    FunctionDecl* fd2 = ma.instantiateFunctionTemplate(fd, tp.getInstanceASTIdx(), tp.getArgs(), tp.getNumArgs());
+    if (!fd2) return QualType_Invalid;
+    fd2.asDecl().setUsed();
+    tp.setDecl(fd2.asDecl());
+    return fd2.asDecl().getType();
+}
+
 fn QualType Analyser.analyseCallExpr(Analyser* ma, Expr** e_ptr) {
     Expr* e = *e_ptr;
     CallExpr* call = (CallExpr*)e;
@@ -60,17 +85,10 @@ fn QualType Analyser.analyseCallExpr(Analyser* ma, Expr** e_ptr) {
     if (fd.hasAttrNoReturn()) call.setNoreturn();
 
     if (fd.isTemplate()) {
-        if (!call.getTemplateArg()) {
-            ma.errorRange(e.getLoc(), e.getRange(), "function %s requires a template argument", fd.asDecl().getFullName());
-            return QualType_Invalid;
-        }
-        fd = ma.instantiateTemplateFunction(call, fd);
-        if (!fd) return QualType_Invalid;
-    } else {
-        if (call.getTemplateArg()) {
-            ma.errorRange(e.getLoc(), e.getRange(), "function %s is not a template function", fd.asDecl().getFullName());
-            return QualType_Invalid;
-        }
+        // TODO handle default type arguments
+        // TODO auto-instantiate based on actual argument types
+        ma.errorRange(e.getLoc(), e.getRange(), "function %s requires a template argument", fd.asDecl().getFullName());
+        return QualType_Invalid;
     }
 
     if (fd.hasAttrDeprecated() && !ma.warnings.no_deprecated) {
@@ -624,12 +642,18 @@ fn void Analyser.opaque_callback(void* arg, SrcLoc loc, Decl* d) {
     ma.error(loc," using opaque type '%s'", qt.diagName());
 }
 
-fn FunctionDecl* Analyser.instantiateTemplateFunction(Analyser* ma, CallExpr* call, FunctionDecl* fd) {
-    TypeRef* template_arg = call.getTemplateArg();
+fn FunctionDecl* Analyser.instantiateFunctionTemplate(Analyser* ma, FunctionDecl* fd, u16 instance_ast_idx, Expr** args, u32 num_args) {
+    // Only handle first argument for now, convert to type
+    TypeRef* template_arg = ma.getTemplateArg(*args);
+    if (!template_arg) return nil;
     QualType templateType = ma.analyseTypeRef(template_arg);
     if (templateType.isInvalid()) return nil;
 
-    FunctionDecl* instance = ma.mod.findInstance(fd, templateType);
+    // TODO create instiator, analyse/evaluate template expressions,
+    //   initialize TemplateSubst array from values or qualtypes,
+    //   compute instance name and check if name exists already
+
+    FunctionDecl* instance = (FunctionDecl*)ma.mod.findInstance(fd.asDecl(), templateType);
     if (!instance) {
         // note: template_arg decl is set here
         bool used_opaque = false;
@@ -639,11 +663,14 @@ fn FunctionDecl* Analyser.instantiateTemplateFunction(Analyser* ma, CallExpr* ca
             Decl* d = (Decl*)std;
             used_opaque = (std.isOpaque() && d.getModule() != ma.mod);
         }
+        // TODO: use TemplateSpec in Instantiator
+        const TemplateSpec* spec = fd.getTemplateSpec();
         Instantiator inst = {
             .c = ma.context,
             .ref = template_arg,
-            .template_name = fd.getTemplateNameIdx(),
-            .instance_ast_idx = call.getInstanceASTIdx(),
+            .template_vars = spec.getTemplateVars(),
+            .template_len = spec.getTemplateLen(),
+            .instance_ast_idx = instance_ast_idx,
             .used_opaque = used_opaque,
             .arg = ma,
             .on_error = Analyser.opaque_callback,
@@ -654,6 +681,13 @@ fn FunctionDecl* Analyser.instantiateTemplateFunction(Analyser* ma, CallExpr* ca
         if (ma.has_error) return nil;
         d.setChecked();
 
+        // add instance to avoid recursive instantiation for the same type
+        u16 instance_idx = ma.mod.addInstance(fd.asDecl(), templateType, instance.asDecl());
+        char[64] name;
+        // TODO: use a more readable name, eg: max$i32
+        create_template_name(name, fd.asDecl().getName(), instance_idx);
+        d.setNameIdx(ma.astPool.addStr(name, true));
+
         // Note: we need a separate scope for the body
         Module* template_mod = fd.asDecl().getModule();
         Analyser* analyser = create(ma.diags, ma.context, ma.astPool, ma.builder, ma.allmodules, ma.warnings);
@@ -669,15 +703,7 @@ fn FunctionDecl* Analyser.instantiateTemplateFunction(Analyser* ma, CallExpr* ca
         analyser.free();
 
         if (ma.has_error) return nil;
-
-        u16 instance_idx = ma.mod.addInstance(fd, templateType, instance);
-        instance.setTemplateInstanceIdx(instance_idx);
-        char[64] name;
-        create_template_name(name, d.getName(), instance_idx);
-        instance.setInstanceName(ma.astPool.addStr(name, true));
     }
-    call.setTemplateIdx(instance.getTemplateInstanceIdx());
-
     return instance;
 }
 

diff --git a/analyser/module_analyser_expr.c2 b/analyser/module_analyser_expr.c2
@@ -67,6 +67,8 @@ fn QualType Analyser.analyseExprInner(Analyser* ma, Expr** e_ptr, u32 side) {
         return d.getType();
     case Type:
         break;
+    case Template:
+        return ma.analyseTemplateExpr(e_ptr);
     case Call:
         return ma.analyseCallExpr(e_ptr);
     case InitList:

diff --git a/analyser/module_analyser_function.c2 b/analyser/module_analyser_function.c2
@@ -22,8 +22,15 @@ import scope;
 // Note: only analyses prototype + args, not the function body
 fn void Analyser.analyseFunction(Analyser* ma, FunctionDecl* fd) {
     if (fd.isTemplate()) {
-        // do analyze template name (eg X) for name clash
-        ma.scope.checkGlobalSymbol(fd.getTemplateNameIdx(), fd.getTemplateLoc());
+        // do analyze template names (eg X) for name clash
+        const TemplateSpec* spec = fd.getTemplateSpec();
+        if (spec) {
+            u32 len = spec.getTemplateLen();
+            const TemplateVar* vars = spec.getTemplateVars();
+            for (u32 i = 0; i < len; i++) {
+                ma.scope.checkGlobalSymbol(vars[i].name, vars[i].loc);
+            }
+        }
 
         // check rtype for array-type
         TypeRef* rtype = fd.getReturnTypeRef();
@@ -128,16 +135,15 @@ fn void Analyser.analyseFunction(Analyser* ma, FunctionDecl* fd) {
     bool is_typefn = false;
     if (num_params && fd.hasPrefix()) {
         // check if SF if first arg is (const) Struct* or (const) Struct
-        // Note: use TypeRef, since it's faster to check
-        const Ref* prefix = fd.getPrefix();
-        const Decl* pd = prefix.decl;
-        assert(pd);
-        QualType prefixType = pd.getType();
-
-        TypeRef* ref = params[0].getTypeRef();
-        const Ref* param_ref = ref.getUser();
-        // Note: for enum types it can be the Type or a pointer to that type
-        bool is_non_static = ((param_ref && param_ref.decl == prefix.decl) || ref.isPointerTo(prefixType.getIndex()));
+        // Note: use TypeRef, since it's simpler to check
+        const Ref* func_prefix = fd.getPrefix();
+        const TypeRef* arg_ref = params[0].getTypeRef();
+        const Ref* user = arg_ref.getUser();
+        bool is_non_static = (user &&
+                              user.name_idx == func_prefix.name_idx &&
+                              arg_ref.getNumPointers() <= 1 &&
+                              !arg_ref.hasPrefix() &&
+                              !arg_ref.isTemplate());
         if (is_non_static) {
             fd.setCallKind(CallKind.TypeFunc);
             is_typefn = true;

diff --git a/analyser/module_analyser_member.c2 b/analyser/module_analyser_member.c2
@@ -120,6 +120,7 @@ fn QualType Analyser.analyseMemberExpr(Analyser* ma, Expr** e_ptr, u32 side) {
                 EnumTypeDecl* etd = et.getDecl();
 
                 // check if constant/enum-function (by first casing)
+                // TODO: incorrect for Enum.Const.min
                 const char* last = m.getLastMemberName();
                 if (ctype.isupper(last[0]) || name_idx == ma.min_idx || name_idx == ma.max_idx) {   // search for constants
                     if (valtype != ValType.NValue) {    // variable of Enum type (eg Enum a; a.x)

diff --git a/analyser/module_analyser_struct.c2 b/analyser/module_analyser_struct.c2
@@ -20,6 +20,17 @@ import name_vector local;
 import size_analyser;
 
 fn void Analyser.analyseStructType(Analyser* ma, StructTypeDecl* d) {
+    if (d.isTemplate()) {
+        // do analyze template names (eg X) for name clash
+        const TemplateSpec* spec = d.getTemplateSpec();
+        u32 len = spec.getTemplateLen();
+        const TemplateVar* vars = spec.getTemplateVars();
+        for (u32 i = 0; i < len; i++) {
+            ma.scope.checkGlobalSymbol(vars[i].name, vars[i].loc);
+        }
+        return;  // only analyse on instantiation
+    }
+
     if (d.isOpaque()) {
         ma.checkStack[ma.checkIndex-1].usedPublic = false;
         ma.usedPublic = false;
@@ -194,10 +205,11 @@ fn void Analyser.analyseStructNames(Analyser* ma, StructTypeDecl* d, NameVector*
             if (names.find(name_idx, &old_index)) {
                 ma.error(member.getLoc(), "duplicate struct/union member '%s'", member.getName());
                 ma.note(locs.get(old_index), "previous declaration is here");
-                return;
+                //return;
+            } else {
+                names.add(name_idx);
+                locs.add(member.getLoc());
             }
-            names.add(name_idx);
-            locs.add(member.getLoc());
 
             if (member.isStructType()) {
                 NameVector sub_names.init(sub.getNumMembers());
@@ -210,4 +222,3 @@ fn void Analyser.analyseStructNames(Analyser* ma, StructTypeDecl* d, NameVector*
     }
 }
 
-