From df6719cb89d9c36866099ca703d06bde530226e2 Mon Sep 17 00:00:00 2001
From: Brody <taylbr97@gmail.com>
Date: Mon, 3 Aug 2026 18:13:12 +1000
Subject: [PATCH 1/7] fix: remove broken special case for poly proc as default
 value

---
 src/check_expr.cpp                | 11 -----------
 tests/issues/run.bat              |  1 +
 tests/issues/run.sh               |  1 +
 tests/issues/test_issue_6753.odin | 27 +++++++++++++++++++++++++++
 4 files changed, 29 insertions(+), 11 deletions(-)
 create mode 100644 tests/issues/test_issue_6753.odin

diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index eea6db2b4..115b13992 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -1023,17 +1023,6 @@ gb_internal bool check_is_assignable_to_with_score(CheckerContext *c, Operand *o
 		return false;
 	}
 
-	// Handle polymorphic procedure used as default parameter
-	if (operand->mode == Addressing_Value && is_type_proc(type) && is_type_proc(operand->type)) {
-		Entity *e = entity_from_expr(operand->expr);
-		if (e != nullptr && e->kind == Entity_Procedure && is_type_polymorphic(e->type) && !is_type_polymorphic(type)) {
-			// Special case: Allow a polymorphic procedure to be used as default value for concrete proc type
-			// during the initial check. It will be properly instantiated when actually used.
-			if (score_) *score_ = assign_score_function(1);
-			return true;
-		}
-	}
-
 	i64 score = check_distance_between_types(c, operand, type, allow_array_programming);
 	if (score >= 0) {
 		if (score_) *score_ = assign_score_function(score, is_variadic);
diff --git a/tests/issues/run.bat b/tests/issues/run.bat
index 8a85ba90a..269c91a0b 100644
--- a/tests/issues/run.bat
+++ b/tests/issues/run.bat
@@ -37,6 +37,7 @@ set COMMON=-define:ODIN_TEST_FANCY=false -file -vet -strict-style -ignore-unused
 ..\..\..\odin test ..\test_pr_6470.odin -define:TEST_EXPECT_FAILURE=true %COMMON% 2>&1 | find /c "Error:" | findstr /x "1" || exit /b
 ..\..\..\odin test ..\test_pr_6476.odin %COMMON%  || exit /b
 ..\..\..\odin check ..\test_issue_6484.odin -no-entry-point %COMMON%  || exit /b
+..\..\..\odin test ..\test_issue_6753.odin %COMMON%  || exit /b
 ..\..\..\odin check ..\test_issue_6874.odin %COMMON% 2>&1 | find /c "Error:" | findstr /x "1" || exit /b
 ..\..\..\odin check ..\test_issue_6979.odin -no-entry-point %COMMON%  || exit /b
 ..\..\..\odin build ..\test_issue_7037.odin %COMMON% -o:none  || exit /b
diff --git a/tests/issues/run.sh b/tests/issues/run.sh
index ce97a570a..9bcc53dfe 100755
--- a/tests/issues/run.sh
+++ b/tests/issues/run.sh
@@ -74,6 +74,7 @@ else
 	exit 1
 fi
 $ODIN check ../test_issue_6484.odin -no-entry-point $COMMON
+$ODIN test ../test_issue_6753.odin -no-entry-point $COMMON
 if [[ $($ODIN check ../test_issue_6874.odin $COMMON 2>&1 >/dev/null | grep -c "Error:") -eq 1 ]] ; then
 	echo "SUCCESSFUL 1/1"
 else
diff --git a/tests/issues/test_issue_6753.odin b/tests/issues/test_issue_6753.odin
new file mode 100644
index 000000000..7f6c7208c
--- /dev/null
+++ b/tests/issues/test_issue_6753.odin
@@ -0,0 +1,27 @@
+// test issue for #6753 https://github.com/odin-lang/odin/issues/6753
+package test_issues
+import "core:testing"
+
+identity :: proc(x: $T) -> T { return x }
+
+foo :: proc(x: int, poly: proc(int) -> int = identity) -> int {
+	return foo(identity(x))
+}
+
+// failing as returns before specialized
+@test
+test_issue_6753 :: proc(t: ^testing.T) {
+    p: proc(int) -> int = identity
+
+	testing.expect(t, p != nil)
+
+    if p != nil {
+		testing.expect(t, p(123) == 123)
+    }
+}
+
+// failing as returns before specialized
+@test
+test_issue_default_poly_parameter_6753 :: proc(t: ^testing.T) {
+	testing.expect(t, foo(123) == 123)
+}
\ No newline at end of file

From 6888e843861a35376679c05d92366a7ad22264c2 Mon Sep 17 00:00:00 2001
From: Brody <taylbr97@gmail.com>
Date: Mon, 3 Aug 2026 18:34:53 +1000
Subject: [PATCH 2/7] fix: Added null check before setting operand type to
 invalid

---
 src/check_type.cpp                |  8 ++++++--
 tests/issues/test_issue_6753.odin | 10 +++-------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/check_type.cpp b/src/check_type.cpp
index be06ca108..ed916ceb2 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -2143,8 +2143,12 @@ gb_internal Type *check_get_params(CheckerContext *ctx, Scope *scope, Ast *_para
 						// This is just to add the error message to determine_type_from_polymorphic which
 						// depends on valid position information
 						op.expr = _params;
-						op.mode = Addressing_Invalid;
-						op.type = t_invalid;
+
+						// NOTE(taylbr): Can still have valid type with null expr. Needed for resolving
+						if (op.mode == Addressing_Invalid || op.type == nullptr) {
+							op.mode = Addressing_Invalid;
+							op.type = t_invalid;
+						}
 					}
 					if (is_type_polymorphic_type) {
 						type = determine_type_from_polymorphic(ctx, type, op);
diff --git a/tests/issues/test_issue_6753.odin b/tests/issues/test_issue_6753.odin
index 7f6c7208c..d4c668c6d 100644
--- a/tests/issues/test_issue_6753.odin
+++ b/tests/issues/test_issue_6753.odin
@@ -12,16 +12,12 @@ foo :: proc(x: int, poly: proc(int) -> int = identity) -> int {
 @test
 test_issue_6753 :: proc(t: ^testing.T) {
     p: proc(int) -> int = identity
-
-	testing.expect(t, p != nil)
-
-    if p != nil {
-		testing.expect(t, p(123) == 123)
-    }
+	testing.expect(t, p != nil, "polymorphic procedure was not instantiated")
+	testing.expect_value(t, p(123), 123)
 }
 
 // failing as returns before specialized
 @test
 test_issue_default_poly_parameter_6753 :: proc(t: ^testing.T) {
-	testing.expect(t, foo(123) == 123)
+	testing.expect_value(t, foo(123), 123)
 }
\ No newline at end of file

From cce1bdd8c751344f01cd17b90a7ceca9dcac2cfe Mon Sep 17 00:00:00 2001
From: Brody <taylbr97@gmail.com>
Date: Mon, 3 Aug 2026 21:42:39 +1000
Subject: [PATCH 3/7] fix: return true for already specialised poly proc

---
 src/check_expr.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 115b13992..8256d9474 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -410,6 +410,15 @@ gb_internal bool find_or_generate_polymorphic_procedure(CheckerContext *old_c, E
 	}
 
 	if (!src->Proc.is_polymorphic || src->Proc.is_poly_specialized) {
+		// NOTE: polymorphic procedure check not idempotent without this
+		if (src->Proc.is_poly_specialized && base_entity->Procedure.generated_from_polymorphic) {
+	    	if (are_types_identical(src, dst)) {
+				if (poly_proc_data) {
+					poly_proc_data->gen_entity = base_entity;
+				}
+				return true;
+			}
+		}
 		return false;
 	}
 

From 87b514890cb2fd3524e6bd9e5e7e12e3a248ca91 Mon Sep 17 00:00:00 2001
From: Brody <taylbr97@gmail.com>
Date: Mon, 3 Aug 2026 22:07:18 +1000
Subject: [PATCH 4/7] fix: instantiated procs keep their own scope

Was this check here for a reason? Investigate
---
 src/check_expr.cpp | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 8256d9474..609173981 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -466,9 +466,7 @@ gb_internal bool find_or_generate_polymorphic_procedure(CheckerContext *old_c, E
 	scope->flags |= ScopeFlag_Proc;
 	nctx.scope = scope;
 	nctx.allow_polymorphic_types = true;
-	if (nctx.polymorphic_scope == nullptr) {
-		nctx.polymorphic_scope = scope;
-	}
+	nctx.polymorphic_scope = scope;
 
 
 	auto *pt = &src->Proc;

From 91e0e6ce473bbad09f225d6a6fcaffa0699f9ee9 Mon Sep 17 00:00:00 2001
From: Brody <taylbr97@gmail.com>
Date: Mon, 3 Aug 2026 22:26:24 +1000
Subject: [PATCH 5/7] fix: record resolved entity for proc-typed default values

---
 src/check_expr.cpp                |  2 +-
 src/check_type.cpp                |  1 +
 src/entity.cpp                    |  1 +
 src/llvm_backend_proc.cpp         |  6 +++
 tests/issues/run.bat              |  1 +
 tests/issues/run.sh               |  8 +++-
 tests/issues/test_issue_5573.odin | 17 +++++++++
 tests/issues/test_issue_6753.odin | 63 +++++++++++++++++++++++++------
 8 files changed, 86 insertions(+), 13 deletions(-)
 create mode 100644 tests/issues/test_issue_5573.odin

diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 609173981..a91664bb0 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -412,7 +412,7 @@ gb_internal bool find_or_generate_polymorphic_procedure(CheckerContext *old_c, E
 	if (!src->Proc.is_polymorphic || src->Proc.is_poly_specialized) {
 		// NOTE: polymorphic procedure check not idempotent without this
 		if (src->Proc.is_poly_specialized && base_entity->Procedure.generated_from_polymorphic) {
-	    	if (are_types_identical(src, dst)) {
+			if (are_types_identical(src, dst)) {
 				if (poly_proc_data) {
 					poly_proc_data->gen_entity = base_entity;
 				}
diff --git a/src/check_type.cpp b/src/check_type.cpp
index ed916ceb2..97f609dd8 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -1791,6 +1791,7 @@ gb_internal ParameterValue handle_parameter_value(CheckerContext *ctx, Type *in_
 					if (e->kind == Entity_Procedure) {
 						param_value.kind = ParameterValue_Constant;
 						param_value.value = exact_value_procedure(e->identifier);
+						param_value.proc_entity = e;
 						add_entity_use(ctx, e->identifier, e);
 					} else {
 						if (e->flags & EntityFlag_Param) {
diff --git a/src/entity.cpp b/src/entity.cpp
index 31f90023b..d3170c823 100644
--- a/src/entity.cpp
+++ b/src/entity.cpp
@@ -111,6 +111,7 @@ enum ParameterValueKind {
 struct ParameterValue {
 	ParameterValueKind kind;
 	Ast *original_ast_expr;
+	Entity *proc_entity;
 	union {
 		ExactValue value;
 		Ast *ast_value;
diff --git a/src/llvm_backend_proc.cpp b/src/llvm_backend_proc.cpp
index 9f1b5dd3f..1cff61ba9 100644
--- a/src/llvm_backend_proc.cpp
+++ b/src/llvm_backend_proc.cpp
@@ -4669,6 +4669,12 @@ gb_internal lbValue lb_build_builtin_proc(lbProcedure *p, Ast *expr, TypeAndValu
 gb_internal lbValue lb_handle_param_value(lbProcedure *p, Type *parameter_type, ParameterValue const &param_value, TypeProc *procedure_type, Ast* call_expression) {
 	switch (param_value.kind) {
 	case ParameterValue_Constant:
+		if (param_value.proc_entity != nullptr && is_type_proc(parameter_type)) {
+			lbValue v = lb_find_procedure_value_from_entity(p->module, param_value.proc_entity);
+			if (v.value != nullptr) {
+				return lb_emit_conv(p, v, parameter_type);
+			}
+		}
 		if (is_type_constant_type(parameter_type)) {
 			auto res = lb_const_value(p->module, parameter_type, param_value.value);
 			return res;
diff --git a/tests/issues/run.bat b/tests/issues/run.bat
index 269c91a0b..6d562ccbc 100644
--- a/tests/issues/run.bat
+++ b/tests/issues/run.bat
@@ -26,6 +26,7 @@ set COMMON=-define:ODIN_TEST_FANCY=false -file -vet -strict-style -ignore-unused
 ..\..\..\odin build ..\test_issue_5097.odin %COMMON% || exit /b
 ..\..\..\odin build ..\test_issue_5097-2.odin %COMMON% || exit /b
 ..\..\..\odin build ..\test_issue_5265.odin %COMMON% || exit /b
+..\..\..\odin build ..\test_issue_5573.odin %COMMON% 2>&1 | find /c "Error:" | findstr /x "2" || exit /b
 ..\..\..\odin test ..\test_issue_5699.odin %COMMON%  || exit /b
 ..\..\..\odin test ..\test_issue_6068.odin %COMMON%  || exit /b
 ..\..\..\odin test ..\test_issue_6101.odin %COMMON%  || exit /b
diff --git a/tests/issues/run.sh b/tests/issues/run.sh
index 9bcc53dfe..49b825bb8 100755
--- a/tests/issues/run.sh
+++ b/tests/issues/run.sh
@@ -32,6 +32,12 @@ $ODIN build ../test_issue_5043.odin $COMMON
 $ODIN build ../test_issue_5097.odin $COMMON
 $ODIN build ../test_issue_5097-2.odin $COMMON
 $ODIN build ../test_issue_5265.odin $COMMON
+if [[ $($ODIN build ../test_issue_5573.odin $COMMON 2>&1 >/dev/null | grep -c "Error:") -eq 2 ]] ; then
+	echo "SUCCESSFUL 1/1"
+else
+	echo "SUCCESSFUL 0/1"
+	exit 1
+fi
 $ODIN test ../test_issue_5699.odin $COMMON
 $ODIN test ../test_issue_6068.odin $COMMON
 $ODIN test ../test_issue_6101.odin $COMMON
@@ -74,7 +80,7 @@ else
 	exit 1
 fi
 $ODIN check ../test_issue_6484.odin -no-entry-point $COMMON
-$ODIN test ../test_issue_6753.odin -no-entry-point $COMMON
+$ODIN test ../test_issue_6753.odin $COMMON
 if [[ $($ODIN check ../test_issue_6874.odin $COMMON 2>&1 >/dev/null | grep -c "Error:") -eq 1 ]] ; then
 	echo "SUCCESSFUL 1/1"
 else
diff --git a/tests/issues/test_issue_5573.odin b/tests/issues/test_issue_5573.odin
new file mode 100644
index 000000000..dd154a89a
--- /dev/null
+++ b/tests/issues/test_issue_5573.odin
@@ -0,0 +1,17 @@
+// Tests issue #5573 https://github.com/odin-lang/Odin/issues/5573
+package test_issues
+
+poly :: proc(x: $T) -> string {
+	return "poly"
+}
+
+takes_concrete :: proc(f: proc(a: int, b: f32, c: rawptr) -> ^int) {
+}
+
+main :: proc() {
+	// should error - wrong arity, wrong parameter types, wrong return type
+	mismatched: proc(a: int, b: f32, c: rawptr) -> ^int = poly
+
+	// should error - same, as a procedure argument
+	takes_concrete(poly)
+}
diff --git a/tests/issues/test_issue_6753.odin b/tests/issues/test_issue_6753.odin
index d4c668c6d..a14b2dc01 100644
--- a/tests/issues/test_issue_6753.odin
+++ b/tests/issues/test_issue_6753.odin
@@ -1,23 +1,64 @@
 // test issue for #6753 https://github.com/odin-lang/odin/issues/6753
 package test_issues
 import "core:testing"
+import "core:fmt"
 
-identity :: proc(x: $T) -> T { return x }
-
-foo :: proc(x: int, poly: proc(int) -> int = identity) -> int {
-	return foo(identity(x))
+foo_concrete :: proc(x: int, g: proc(int) -> int) -> int {
+	return g(x)
+}
+foo_impossible :: proc(x: int, g: proc(int, int) -> string) -> string {
+	return "impossible"
+}
+foo_group :: proc {
+	foo_concrete,
+	foo_impossible,
+}
+
+f_poly :: proc(x: $T) -> T { return x }
+foo_poly :: proc(x: $T, g: proc(T) -> T = f_poly) -> T {
+	return g(x)
 }
 
-// failing as returns before specialized
 @test
-test_issue_6753 :: proc(t: ^testing.T) {
-    p: proc(int) -> int = identity
+test_issue_6753_ambiguous_poly_argumentment :: proc (t: ^testing.T) {
+    testing.expect_value(t, foo_group(1, f_poly), 1) // should be no ambiguity whether foo_concrete or foo_impossible
+}
+
+@test
+test_issue_6753_default_poly_proc :: proc (t: ^testing.T) {
+    testing.expect_value(t, foo_poly(1), 1)
+}
+
+@test
+test_issue_6753_parapoly_proc_variable :: proc(t: ^testing.T) {
+    p: proc(int) -> int = f_poly
 	testing.expect(t, p != nil, "polymorphic procedure was not instantiated")
 	testing.expect_value(t, p(123), 123)
 }
 
-// failing as returns before specialized
+// -- Fixing above led to some new bugs surfacing --
 @test
-test_issue_default_poly_parameter_6753 :: proc(t: ^testing.T) {
-	testing.expect_value(t, foo(123), 123)
-}
\ No newline at end of file
+test_issue_6753_parapoly_proc_as_argument :: proc(t: ^testing.T) {
+	testing.expect(t, foo_concrete(123, f_poly) == 123, "failed to pass poly proc as argument")
+}
+
+@test
+test_issue_6753_parapoly_with_default_proc_same_generic_type_T :: proc(t: ^testing.T) {
+	testing.expect_value(t, foo_poly(123), 123)
+	testing.expect_value(t, foo_poly(123, f_poly), 123)
+}
+
+// all together now
+describe :: proc(x: $T) -> string { return fmt.tprintf("#%v", x) }
+describe_bytes :: proc(x: []byte) -> string { return "bytes" }
+
+bar_poly  :: proc(x: $T, g: proc(x: T) -> string = describe) -> string { return g(x) }
+bar_bytes :: proc(x: []byte, g: proc(x: []byte) -> string) -> string { return g(x) }
+bar_group :: proc { bar_poly, bar_bytes }
+
+@test
+test_issue_6753_parapoly_default_in_group :: proc(t: ^testing.T) {
+      testing.expect_value(t, bar_group(123, describe), "#123")
+      testing.expect_value(t, bar_group("hi"), "#hi")
+      testing.expect_value(t, bar_group([]byte{1, 2}, describe_bytes), "bytes")
+}

From 90f6c9d0dbb7739aa3e8a0a59576112473065a56 Mon Sep 17 00:00:00 2001
From: Brody <taylbr97@gmail.com>
Date: Wed, 5 Aug 2026 00:17:48 +1000
Subject: [PATCH 6/7] whitespace

---
 tests/issues/test_issue_5573.odin |  1 +
 tests/issues/test_issue_6753.odin | 14 +++++++-------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/tests/issues/test_issue_5573.odin b/tests/issues/test_issue_5573.odin
index dd154a89a..150f95863 100644
--- a/tests/issues/test_issue_5573.odin
+++ b/tests/issues/test_issue_5573.odin
@@ -11,6 +11,7 @@ takes_concrete :: proc(f: proc(a: int, b: f32, c: rawptr) -> ^int) {
 main :: proc() {
 	// should error - wrong arity, wrong parameter types, wrong return type
 	mismatched: proc(a: int, b: f32, c: rawptr) -> ^int = poly
+	_ = mismatched
 
 	// should error - same, as a procedure argument
 	takes_concrete(poly)
diff --git a/tests/issues/test_issue_6753.odin b/tests/issues/test_issue_6753.odin
index a14b2dc01..26531ae31 100644
--- a/tests/issues/test_issue_6753.odin
+++ b/tests/issues/test_issue_6753.odin
@@ -20,18 +20,18 @@ foo_poly :: proc(x: $T, g: proc(T) -> T = f_poly) -> T {
 }
 
 @test
-test_issue_6753_ambiguous_poly_argumentment :: proc (t: ^testing.T) {
-    testing.expect_value(t, foo_group(1, f_poly), 1) // should be no ambiguity whether foo_concrete or foo_impossible
+test_issue_6753_ambiguous_poly_argument :: proc (t: ^testing.T) {
+	testing.expect_value(t, foo_group(1, f_poly), 1) // should be no ambiguity whether foo_concrete or foo_impossible
 }
 
 @test
 test_issue_6753_default_poly_proc :: proc (t: ^testing.T) {
-    testing.expect_value(t, foo_poly(1), 1)
+	testing.expect_value(t, foo_poly(1), 1)
 }
 
 @test
 test_issue_6753_parapoly_proc_variable :: proc(t: ^testing.T) {
-    p: proc(int) -> int = f_poly
+	p: proc(int) -> int = f_poly
 	testing.expect(t, p != nil, "polymorphic procedure was not instantiated")
 	testing.expect_value(t, p(123), 123)
 }
@@ -58,7 +58,7 @@ bar_group :: proc { bar_poly, bar_bytes }
 
 @test
 test_issue_6753_parapoly_default_in_group :: proc(t: ^testing.T) {
-      testing.expect_value(t, bar_group(123, describe), "#123")
-      testing.expect_value(t, bar_group("hi"), "#hi")
-      testing.expect_value(t, bar_group([]byte{1, 2}, describe_bytes), "bytes")
+	testing.expect_value(t, bar_group(123, describe), "#123")
+	testing.expect_value(t, bar_group("hi"), "#hi")
+	testing.expect_value(t, bar_group([]byte{1, 2}, describe_bytes), "bytes")
 }

From 21fd0c4645467c3259ccf7fb3b755b2d66cdcba9 Mon Sep 17 00:00:00 2001
From: Brody <taylbr97@gmail.com>
Date: Wed, 5 Aug 2026 00:40:13 +1000
Subject: [PATCH 7/7] fix: bad merge

---
 tests/issues/run.sh | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/tests/issues/run.sh b/tests/issues/run.sh
index 62213e0c9..0d41652c2 100755
--- a/tests/issues/run.sh
+++ b/tests/issues/run.sh
@@ -81,15 +81,8 @@ else
 	echo "SUCCESSFUL 0/1"
 	exit 1
 fi
-$ODIN check ../test_issue_6484.odin -no-entry-point $COMMON
-$ODIN test ../test_issue_6753.odin $COMMON
-if [[ $($ODIN check ../test_issue_6874.odin $COMMON 2>&1 >/dev/null | grep -c "Error:") -eq 1 ]] ; then
 $ODIN check ../test_issue_6484.odin -no-entry-point $COMMON_CHECK
-	echo "SUCCESSFUL 1/1"
-else
-	echo "SUCCESSFUL 0/1"
-	exit 1
-fi
+$ODIN test ../test_issue_6753.odin $COMMON
 if [[ $($ODIN check ../test_issue_6874.odin $COMMON_CHECK 2>&1 >/dev/null | grep -c "Error:") -eq 1 ]] ; then
 	echo "SUCCESSFUL 1/1"
 else