diff --git a/toolchain/parser/parser.cpp b/toolchain/parser/parser.cpp
index 4ca8687b2470..3d13c3821dd6 100644
--- a/toolchain/parser/parser.cpp
+++ b/toolchain/parser/parser.cpp
@@ -778,13 +778,32 @@ auto Parser::HandleDeclarationLoopState() -> void {
   }
 }
 
+auto Parser::HandleDeducedParameterState() -> void {
+  PopAndDiscardState();
+
+  PushState(ParserState::DeducedParameterFinish);
+  PushState(ParserState::PatternAsDeducedParameter);
+}
+
+auto Parser::HandleDeducedParameterFinishState() -> void {
+  auto state = PopState();
+
+  if (state.has_error) {
+    ReturnErrorOnState();
+  }
+
+  if (ConsumeListToken(ParseNodeKind::ParameterListComma,
+                       TokenKind::CloseSquareBracket,
+                       state.has_error) == ListTokenKind::Comma) {
+    PushState(ParserState::DeducedParameter);
+  }
+}
+
 auto Parser::HandleDeducedParameterListFinishState() -> void {
   auto state = PopState();
 
-  CARBON_CHECK(tokens_->GetKind(*position_) == TokenKind::CloseSquareBracket)
-      << "Expected current token to be: `]`, found: "
-      << tokens_->GetKind(state.token);
-  AddNode(ParseNodeKind::DeducedParameterList, Consume(), state.subtree_start,
+  AddNode(ParseNodeKind::DeducedParameterList,
+          ConsumeChecked(TokenKind::CloseSquareBracket), state.subtree_start,
           state.has_error);
 }
 
@@ -1049,26 +1068,22 @@ auto Parser::HandleFunctionIntroducerState() -> void {
     return;
   }
 
+  // Proceed to the same state regardless of whether there's a deduced
+  // parameter list.
   state.state = ParserState::FunctionAfterDeducedParameterList;
   PushState(state);
 
-  // If there are deduced params handle them next.
-  if (PositionIs(TokenKind::OpenSquareBracket)) {
-    PushState(ParserState::DeducedParameterListFinish);
-    // This is for sure a `[`, we can safely create the corresponding node.
-    AddLeafNode(ParseNodeKind::DeducedParameterListStart, Consume());
-
-    if (PositionIs(TokenKind::CloseSquareBracket)) {
-      return;
-    }
-
-    // TODO: For now only `self` is supported. When other types of deduced
-    // parameters need to be added, we will probably need to push a more
-    // general state.
-    // Push state to handle `self`'s pattern binding.
-    PushState(ParserState::SelfPattern);
+  if (!PositionIs(TokenKind::OpenSquareBracket)) {
     return;
   }
+
+  // Parse the deduced parameter list as its own subtree.
+  PushState(ParserState::DeducedParameterListFinish);
+  AddLeafNode(ParseNodeKind::DeducedParameterListStart, Consume());
+
+  if (!PositionIs(TokenKind::CloseSquareBracket)) {
+    PushState(ParserState::DeducedParameter);
+  }
 }
 
 auto Parser::HandleFunctionAfterDeducedParameterListState() -> void {
@@ -1437,13 +1452,26 @@ auto Parser::HandleParenExpressionFinishAsTupleState() -> void {
 auto Parser::HandlePattern(PatternKind pattern_kind) -> void {
   auto state = PopState();
 
-  // Ensure the finish state always follows.
+  // Ensure the finish state always follows, including for errors.
   state.state = ParserState::PatternFinish;
 
+  // Parameters may have an `addr` keyword prefixing the pattern. This becomes
+  // the parent for the full PatternBinding.
+  if (pattern_kind != PatternKind::Variable) {
+    if (auto addr = ConsumeIf(TokenKind::Addr)) {
+      // Mirror information including subtree_size, but we need to change a copy
+      // to avoid affecting the token.
+      auto addr_state = state;
+      addr_state.state = ParserState::PatternAddress;
+      addr_state.token = *addr;
+      PushState(addr_state);
+    }
+  }
+
   // Handle an invalid pattern introducer for parameters and variables.
-  if (!PositionIs(TokenKind::Identifier) ||
-      tokens_->GetKind(*(position_ + 1)) != TokenKind::Colon) {
+  auto on_error = [&]() {
     switch (pattern_kind) {
+      case PatternKind::DeducedParameter:
       case PatternKind::Parameter: {
         CARBON_DIAGNOSTIC(ExpectedParameterName, Error,
                           "Expected parameter declaration.");
@@ -1459,16 +1487,36 @@ auto Parser::HandlePattern(PatternKind pattern_kind) -> void {
     }
     state.has_error = true;
     PushState(state);
+  };
+
+  // The first item should be an identifier or, for deduced parameters, `self`.
+  if (auto identifier = ConsumeIf(TokenKind::Identifier)) {
+    AddLeafNode(ParseNodeKind::DeclaredName, *identifier);
+  } else if (pattern_kind == PatternKind::DeducedParameter) {
+    if (auto self = ConsumeIf(TokenKind::SelfParameter)) {
+      AddLeafNode(ParseNodeKind::SelfDeducedParameter, *self);
+    } else {
+      on_error();
+      return;
+    }
+  } else {
+    on_error();
     return;
   }
 
-  // Switch the context token to the colon, so that it'll be used for the root
-  // node.
-  state.token = *(position_ + 1);
-  PushState(state);
-  PushStateForExpression(PrecedenceGroup::ForType());
-  AddLeafNode(ParseNodeKind::DeclaredName, *position_);
-  position_ += 2;
+  if (auto colon = ConsumeIf(TokenKind::Colon)) {
+    // Use the colon for the root node.
+    state.token = *colon;
+    PushState(state);
+    PushStateForExpression(PrecedenceGroup::ForType());
+  } else {
+    on_error();
+    return;
+  }
+}
+
+auto Parser::HandlePatternAsDeducedParameterState() -> void {
+  HandlePattern(PatternKind::DeducedParameter);
 }
 
 auto Parser::HandlePatternAsFunctionParameterState() -> void {
@@ -1496,75 +1544,13 @@ auto Parser::HandlePatternFinishState() -> void {
 auto Parser::HandlePatternAddressState() -> void {
   auto state = PopState();
 
-  // If an error was encountered, propagate it without adding a node.
+  AddNode(ParseNodeKind::Address, state.token, state.subtree_start,
+          state.has_error);
+
+  // If an error was encountered, propagate it while adding a node.
   if (state.has_error) {
     ReturnErrorOnState();
-    return;
   }
-
-  AddNode(ParseNodeKind::Address, state.token, state.subtree_start,
-          /*has_error=*/false);
-}
-
-// TODO: This can possibly be merged with `HandlePattern`. Regular function
-// parameters support `addr` as well but it is not implemented yet.
-auto Parser::HandleSelfPatternState() -> void {
-  auto state = PopState();
-
-  // self `:` type
-  auto possible_self_param =
-      (PositionIs(TokenKind::SelfParameter) &&
-       tokens_->GetKind(*(position_ + 1)) == TokenKind::Colon);
-
-  if (possible_self_param) {
-    // Ensure the finish state always follows.
-    state.state = ParserState::PatternFinish;
-
-    // Switch the context token to the colon, so that it'll be used for the root
-    // node.
-    state.token = *(position_ + 1);
-    PushState(state);
-    PushStateForExpression(PrecedenceGroup::ForType());
-    AddLeafNode(ParseNodeKind::SelfDeducedParameter, *position_);
-    position_ += 2;
-    return;
-  }
-
-  // addr self `:` type
-  auto possible_addr_self_param =
-      (PositionIs(TokenKind::Addr) &&
-       tokens_->GetKind(*(position_ + 1)) == TokenKind::SelfParameter &&
-       tokens_->GetKind(*(position_ + 2)) == TokenKind::Colon);
-
-  if (possible_addr_self_param) {
-    // Ensure the finish state always follows.
-    state.state = ParserState::PatternAddress;
-    state.token = Consume();
-    PushState(state);
-
-    PushState(ParserState::PatternFinish);
-
-    PushStateForExpression(PrecedenceGroup::ForType());
-    AddLeafNode(ParseNodeKind::SelfDeducedParameter, *(position_ + 1));
-    position_ += 2;
-    return;
-  }
-
-  CARBON_DIAGNOSTIC(ExpectedDeducedParam, Error,
-                    "Deduced parameters must be of the form: `<name>: <Type>` "
-                    "or `addr <name>: <Type>`.");
-  emitter_->Emit(*position_, ExpectedDeducedParam);
-  state.state = ParserState::PatternFinish;
-  state.has_error = true;
-
-  // Try to recover by skipping to the next `]`.
-  if (auto next_close_square_bracket =
-          FindNextOf({TokenKind::CloseSquareBracket});
-      next_close_square_bracket) {
-    SkipTo(*next_close_square_bracket);
-  }
-
-  PushState(state);
 }
 
 auto Parser::HandleStatementState() -> void {
diff --git a/toolchain/parser/parser.h b/toolchain/parser/parser.h
index a3a8f90e2511..680db42dbd2c 100644
--- a/toolchain/parser/parser.h
+++ b/toolchain/parser/parser.h
@@ -44,7 +44,7 @@ class Parser {
   enum class BraceExpressionKind { Unknown, Value, Type };
 
   // Supported kinds for HandlePattern.
-  enum class PatternKind { Parameter, Variable };
+  enum class PatternKind { DeducedParameter, Parameter, Variable };
 
   // Supported return values for GetDeclarationContext.
   enum class DeclarationContext {
@@ -310,7 +310,7 @@ class Parser {
   // Handles ParenExpressionParameterFinishAs(Unknown|Tuple).
   auto HandleParenExpressionParameterFinish(bool as_tuple) -> void;
 
-  // Handles PatternAs(FunctionParameter|Variable).
+  // Handles PatternAs(DeducedParameter|FunctionParameter|Variable).
   auto HandlePattern(PatternKind pattern_kind) -> void;
 
   // Handles the `;` after a keyword statement.
diff --git a/toolchain/parser/parser_state.def b/toolchain/parser/parser_state.def
index bf83e378b22f..3675db8e2d2f 100644
--- a/toolchain/parser/parser_state.def
+++ b/toolchain/parser/parser_state.def
@@ -145,7 +145,23 @@ CARBON_PARSER_STATE(CodeBlockFinish)
 //   1. DeclarationLoop
 CARBON_PARSER_STATE(DeclarationLoop)
 
-// To handle parsing deduced parameter list at the end.
+// Starts deduced parameter processing.
+//
+// Always:
+//   1. PatternAsDeducedParameter
+//   2. DeducedParameterFinish
+CARBON_PARSER_STATE(DeducedParameter)
+
+// Finishes deduced parameter processing, including `,`. If there are more
+// parameters, enqueues another parameter processing state.
+//
+// If `Comma` without `CloseSquareBracket`:
+//   1. DeducedParameter
+// Else:
+//   (state done)
+CARBON_PARSER_STATE(DeducedParameterFinish)
+
+// Handles processing of a deduced parameter list `]`.
 //
 // Always:
 //   (state done)
@@ -233,6 +249,19 @@ CARBON_PARSER_STATE(ExpressionStatementFinish)
 //
 // If invalid:
 //   (state done)
+// If deduced parameters:
+//   1. DeducedParameter
+//   2. DeducedParameterListFinish
+//   3. FunctionAfterDeducedParameterList
+// Else:
+//   1. FunctionAfterDeducedParameterList
+CARBON_PARSER_STATE(FunctionIntroducer)
+
+// Handles processing of a functions' syntax after the deduced parameter lists's
+// `]`. This applies only to interfaces and classes.
+//
+// If invalid:
+//   (state done)
 // If parenthesized parameters:
 //   1. FunctionParameter
 //   2. FunctionParameterListFinish
@@ -240,7 +269,7 @@ CARBON_PARSER_STATE(ExpressionStatementFinish)
 // Else:
 //   1. FunctionParameterListFinish
 //   2. FunctionAfterParameterList
-CARBON_PARSER_STATE(FunctionIntroducer)
+CARBON_PARSER_STATE(FunctionAfterDeducedParameterList)
 
 // Starts function parameter processing.
 //
@@ -373,13 +402,14 @@ CARBON_PARSER_STATE(ParenExpressionFinish)
 CARBON_PARSER_STATE(ParenExpressionFinishAsTuple)
 
 // Handles pattern parsing for a pattern, enqueuing type expression processing.
-// This covers function parameter and `var` support.
+// This covers parameter and `var` support.
 //
 // If valid:
 //   1. Expression
 //   2. PatternFinish
 // Else:
 //   1. PatternFinish
+CARBON_PARSER_STATE(PatternAsDeducedParameter)
 CARBON_PARSER_STATE(PatternAsFunctionParameter)
 CARBON_PARSER_STATE(PatternAsVariable)
 
@@ -395,15 +425,6 @@ CARBON_PARSER_STATE(PatternAddress)
 //   (state done)
 CARBON_PARSER_STATE(PatternFinish)
 
-// To start parsing `self` deduced parameter.
-//
-// If valid:
-//   1. Expression
-//   2. PatternFinish
-// Else:
-//   1. PatternFinish
-CARBON_PARSER_STATE(SelfPattern)
-
 // Handles a single statement. While typically within a statement block, this
 // can also be used for error recovery where we expect a statement block and
 // are missing braces.
@@ -579,18 +600,4 @@ CARBON_PARSER_STATE(VarAfterPattern)
 CARBON_PARSER_STATE(VarFinishAsSemicolon)
 CARBON_PARSER_STATE(VarFinishAsFor)
 
-// Handles processing of a functions' syntax after the deduced parameter lists's
-// `]`. This applies only to interfaces and classes.
-//
-// If invalid:
-//   (state done)
-// If parenthesized parameters:
-//   1. FunctionParameter
-//   2. FunctionParameterListFinish
-//   3. FunctionAfterParameterList
-// Else:
-//   1. FunctionParameterListFinish
-//   2. FunctionAfterParameterList
-CARBON_PARSER_STATE(FunctionAfterDeducedParameterList)
-
 #undef CARBON_PARSER_STATE
diff --git a/toolchain/parser/testdata/function/declaration/addr.carbon b/toolchain/parser/testdata/function/declaration/addr.carbon
new file mode 100644
index 000000000000..8ca84ed9fcd6
--- /dev/null
+++ b/toolchain/parser/testdata/function/declaration/addr.carbon
@@ -0,0 +1,21 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'foo'},
+// CHECK:STDOUT:     {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:         {kind: 'DeclaredName', text: 'a'},
+// CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:         {kind: 'PostfixOperator', text: '*', subtree_size: 2},
+// CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 4},
+// CHECK:STDOUT:     {kind: 'Address', text: 'addr', subtree_size: 5},
+// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', subtree_size: 7},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 10},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+fn foo(addr a: i32*);
diff --git a/toolchain/parser/testdata/function/declaration/deduced_one.carbon b/toolchain/parser/testdata/function/declaration/deduced_one.carbon
new file mode 100644
index 000000000000..b7534ee18659
--- /dev/null
+++ b/toolchain/parser/testdata/function/declaration/deduced_one.carbon
@@ -0,0 +1,21 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'foo'},
+// CHECK:STDOUT:     {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'a'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:   {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:     {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', subtree_size: 2},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 10},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+fn foo[a: i32]();
diff --git a/toolchain/parser/testdata/function/declaration/deduced_one_suffix_comma.carbon b/toolchain/parser/testdata/function/declaration/deduced_one_suffix_comma.carbon
new file mode 100644
index 000000000000..01e130ca7929
--- /dev/null
+++ b/toolchain/parser/testdata/function/declaration/deduced_one_suffix_comma.carbon
@@ -0,0 +1,22 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'foo'},
+// CHECK:STDOUT:     {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'a'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:   {kind: 'DeducedParameterList', text: ']', subtree_size: 6},
+// CHECK:STDOUT:     {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', subtree_size: 2},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 11},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+fn foo[a: i32,]();
diff --git a/toolchain/parser/testdata/function/declaration/deduced_six.carbon b/toolchain/parser/testdata/function/declaration/deduced_six.carbon
new file mode 100644
index 000000000000..306c5271ca2c
--- /dev/null
+++ b/toolchain/parser/testdata/function/declaration/deduced_six.carbon
@@ -0,0 +1,41 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'foo'},
+// CHECK:STDOUT:     {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'a'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'b'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'c'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'd'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'e'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'f'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:   {kind: 'DeducedParameterList', text: ']', subtree_size: 25},
+// CHECK:STDOUT:     {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', subtree_size: 2},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 30},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+fn foo[a: i32, b: i32, c: i32, d: i32, e: i32, f: i32]();
diff --git a/toolchain/parser/testdata/function/declaration/deduced_two.carbon b/toolchain/parser/testdata/function/declaration/deduced_two.carbon
new file mode 100644
index 000000000000..df9726332fb1
--- /dev/null
+++ b/toolchain/parser/testdata/function/declaration/deduced_two.carbon
@@ -0,0 +1,25 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'foo'},
+// CHECK:STDOUT:     {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'a'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'b'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:   {kind: 'DeducedParameterList', text: ']', subtree_size: 9},
+// CHECK:STDOUT:     {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', subtree_size: 2},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 14},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+fn foo[a: i32, b: i32]();
diff --git a/toolchain/parser/testdata/function/declaration/deduced_two_suffix_comma.carbon b/toolchain/parser/testdata/function/declaration/deduced_two_suffix_comma.carbon
new file mode 100644
index 000000000000..30bebd69cb8a
--- /dev/null
+++ b/toolchain/parser/testdata/function/declaration/deduced_two_suffix_comma.carbon
@@ -0,0 +1,26 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'foo'},
+// CHECK:STDOUT:     {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'a'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'b'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
+// CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterListComma', text: ','},
+// CHECK:STDOUT:   {kind: 'DeducedParameterList', text: ']', subtree_size: 10},
+// CHECK:STDOUT:     {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', subtree_size: 2},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 15},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+fn foo[a: i32, b: i32,]();
diff --git a/toolchain/parser/testdata/function/declaration/fail_missing_deduced_close.carbon b/toolchain/parser/testdata/function/declaration/fail_missing_deduced_close.carbon
new file mode 100644
index 000000000000..0f79c7e73646
--- /dev/null
+++ b/toolchain/parser/testdata/function/declaration/fail_missing_deduced_close.carbon
@@ -0,0 +1,20 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{not} %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'Div'},
+// CHECK:STDOUT:     {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:   {kind: 'DeducedParameterList', text: ']', has_error: yes, subtree_size: 2},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: 'fn', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+// Fix and uncomment this to test error handling.
+// CHECK:STDERR: {{.*}}/toolchain/parser/testdata/function/declaration/fail_missing_deduced_close.carbon:[[@LINE+2]]:7: Closing symbol does not match most recent opening symbol.
+// CHECK:STDERR: {{.*}}/toolchain/parser/testdata/function/declaration/fail_missing_deduced_close.carbon:[[@LINE+1]]:8: Expected parameter declaration.
+fn Div[();
+// CHECK:STDERR: {{.*}}/toolchain/parser/testdata/function/declaration/fail_missing_deduced_close.carbon:[[@LINE+0]]:156: Expected `(` after function name.
diff --git a/toolchain/parser/testdata/function/declaration/fail_with_identifier_as_param.carbon b/toolchain/parser/testdata/function/declaration/fail_with_identifier_as_param.carbon
index 74aca5b2360d..7ea5f6a8d279 100644
--- a/toolchain/parser/testdata/function/declaration/fail_with_identifier_as_param.carbon
+++ b/toolchain/parser/testdata/function/declaration/fail_with_identifier_as_param.carbon
@@ -8,10 +8,11 @@
 // CHECK:STDOUT:   {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:   {kind: 'DeclaredName', text: 'foo'},
 // CHECK:STDOUT:     {kind: 'ParameterListStart', text: '('},
-// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', has_error: yes, subtree_size: 2},
-// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 5},
+// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'bar'},
+// CHECK:STDOUT:   {kind: 'ParameterList', text: ')', has_error: yes, subtree_size: 3},
+// CHECK:STDOUT: {kind: 'FunctionDeclaration', text: ';', subtree_size: 6},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT: ]
 
-// CHECK:STDERR: {{.*}}/toolchain/parser/testdata/function/declaration/fail_with_identifier_as_param.carbon:[[@LINE+1]]:8: Expected parameter declaration.
+// CHECK:STDERR: {{.*}}/toolchain/parser/testdata/function/declaration/fail_with_identifier_as_param.carbon:[[@LINE+1]]:11: Expected parameter declaration.
 fn foo(bar);
diff --git a/toolchain/parser/testdata/generics/interface/basic.carbon b/toolchain/parser/testdata/generics/interface/basic.carbon
index 6ebf323e705a..bb9fc4f05980 100644
--- a/toolchain/parser/testdata/generics/interface/basic.carbon
+++ b/toolchain/parser/testdata/generics/interface/basic.carbon
@@ -38,56 +38,11 @@
 // CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
 // CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
 // CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 15},
-// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
-// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Sub'},
-// CHECK:STDOUT:       {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:           {kind: 'SelfDeducedParameter', text: ':'},
-// CHECK:STDOUT:             {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:           {kind: 'PostfixOperator', text: '*', subtree_size: 2},
-// CHECK:STDOUT:         {kind: 'PatternBinding', text: 'self', subtree_size: 4},
-// CHECK:STDOUT:       {kind: 'Address', text: 'addr', subtree_size: 5},
-// CHECK:STDOUT:     {kind: 'DeducedParameterList', text: ']', subtree_size: 7},
-// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
-// CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
-// CHECK:STDOUT:         {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
-// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
-// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 17},
-// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
-// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Sub'},
-// CHECK:STDOUT:       {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:           {kind: 'SelfDeducedParameter', text: ':'},
-// CHECK:STDOUT:             {kind: 'NameReference', text: 'foo'},
-// CHECK:STDOUT:           {kind: 'PostfixOperator', text: '*', subtree_size: 2},
-// CHECK:STDOUT:         {kind: 'PatternBinding', text: 'self', subtree_size: 4},
-// CHECK:STDOUT:       {kind: 'Address', text: 'addr', subtree_size: 5},
-// CHECK:STDOUT:     {kind: 'DeducedParameterList', text: ']', subtree_size: 7},
-// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
-// CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
-// CHECK:STDOUT:         {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
-// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
-// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 17},
-// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
-// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'FooFactory'},
-// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
-// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 2},
-// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
-// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 7},
-// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 75},
+// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 34},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT: ]
+
 interface Foo {
   fn Add[self: Self](b: Self) -> Self;
   fn Add[self: foo](b: Self) -> Self;
-
-  fn Sub[addr self: Self*](b: Self) -> Self;
-  fn Sub[addr self: foo*](b: Self) -> Self;
-
-  fn FooFactory() -> Self;
 }
diff --git a/toolchain/parser/testdata/generics/interface/declaration.carbon b/toolchain/parser/testdata/generics/interface/declaration.carbon
index 5e7ba8165d34..f8f405f2f672 100644
--- a/toolchain/parser/testdata/generics/interface/declaration.carbon
+++ b/toolchain/parser/testdata/generics/interface/declaration.carbon
@@ -5,9 +5,12 @@
 // AUTOUPDATE
 // RUN: %{carbon-run-parser}
 // CHECK:STDOUT: [
-// CHECK:STDOUT:   {kind: 'InterfaceIntroducer', text: 'interface'},
-// CHECK:STDOUT:   {kind: 'DeclaredName', text: 'Foo'},
-// CHECK:STDOUT: {kind: 'InterfaceDeclaration', text: ';', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'InterfaceIntroducer', text: 'interface'},
+// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Foo'},
+// CHECK:STDOUT:   {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
+// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 4},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT: ]
-interface Foo;
+
+interface Foo {
+}
diff --git a/toolchain/parser/testdata/generics/interface/empty.carbon b/toolchain/parser/testdata/generics/interface/empty_body.carbon
similarity index 100%
rename from toolchain/parser/testdata/generics/interface/empty.carbon
rename to toolchain/parser/testdata/generics/interface/empty_body.carbon
diff --git a/toolchain/parser/testdata/generics/interface/fail_no_impl_allowed.carbon b/toolchain/parser/testdata/generics/interface/fail_no_impl_allowed.carbon
index 5ead4add9238..4ca80fe00dd6 100644
--- a/toolchain/parser/testdata/generics/interface/fail_no_impl_allowed.carbon
+++ b/toolchain/parser/testdata/generics/interface/fail_no_impl_allowed.carbon
@@ -26,6 +26,7 @@
 // CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 19},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT: ]
+
 interface Foo {
   // CHECK:STDERR: {{.*}}/toolchain/parser/testdata/generics/interface/fail_no_impl_allowed.carbon:[[@LINE+1]]:39: Method implementations are not allowed in interfaces.
   fn Add[self: Self](b: Self) -> Self {
diff --git a/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon b/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon
index c18cd69948b8..9bbb9055fc24 100644
--- a/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon
+++ b/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon
@@ -9,19 +9,10 @@
 // CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Foo'},
 // CHECK:STDOUT:   {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
-// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Add'},
-// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
-// CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
-// CHECK:STDOUT:         {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
-// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
-// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 10},
-// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Sub'},
 // CHECK:STDOUT:       {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:     {kind: 'DeducedParameterList', text: ']', has_error: yes, subtree_size: 2},
+// CHECK:STDOUT:       {kind: 'DeclaredName', text: 'me'},
+// CHECK:STDOUT:     {kind: 'DeducedParameterList', text: ']', has_error: yes, subtree_size: 3},
 // CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
 // CHECK:STDOUT:         {kind: 'SelfType', text: 'Self'},
@@ -29,7 +20,7 @@
 // CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
 // CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
 // CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
-// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 12},
+// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 13},
 // CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Mul'},
 // CHECK:STDOUT:       {kind: 'DeducedParameterListStart', text: '['},
@@ -42,37 +33,14 @@
 // CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
 // CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
 // CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 12},
-// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
-// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Rem'},
-// CHECK:STDOUT:       {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:     {kind: 'DeducedParameterList', text: ']', subtree_size: 2},
-// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
-// CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
-// CHECK:STDOUT:         {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
-// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
-// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
-// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 12},
-// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 50},
+// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 29},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT: ]
-interface Foo {
-  fn Add(b: Self) -> Self;
 
-  // CHECK:STDERR: {{.*}}/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon:[[@LINE+1]]:10: Deduced parameters must be of the form: `<name>: <Type>` or `addr <name>: <Type>`.
+interface Foo {
+  // CHECK:STDERR: {{.*}}/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon:[[@LINE+1]]:13: Expected parameter declaration.
   fn Sub[me Self](b: Self) -> Self;
 
-  // CHECK:STDERR: {{.*}}/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon:[[@LINE+1]]:10: Deduced parameters must be of the form: `<name>: <Type>` or `addr <name>: <Type>`.
+  // CHECK:STDERR: {{.*}}/toolchain/parser/testdata/generics/interface/fail_self_param_syntax.carbon:[[@LINE+1]]:10: Expected parameter declaration.
   fn Mul[Self](b: Self) -> Self;
-
-  // TODO: The recovery token is currently inserted after the `;`:
-  // ```
-  // fn Div[me: Self(b: Self) -> Self;]
-  // ```
-  // Fix and uncomment this to test error handling.
-  // fn Div[me: Self(b: Self) -> Self;
-
-  // It is fine to have an empty deduced parameter list.
-  fn Rem[](b: Self) -> Self;
 }
diff --git a/toolchain/parser/testdata/generics/interface/non_instance_fn.carbon b/toolchain/parser/testdata/generics/interface/non_instance_fn.carbon
new file mode 100644
index 000000000000..12ababbba5a4
--- /dev/null
+++ b/toolchain/parser/testdata/generics/interface/non_instance_fn.carbon
@@ -0,0 +1,24 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:     {kind: 'InterfaceIntroducer', text: 'interface'},
+// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Foo'},
+// CHECK:STDOUT:   {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'FooFactory'},
+// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 2},
+// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
+// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
+// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 7},
+// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 11},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+interface Foo {
+  fn FooFactory() -> Self;
+}
diff --git a/toolchain/parser/testdata/generics/interface/self_pointer.carbon b/toolchain/parser/testdata/generics/interface/self_pointer.carbon
new file mode 100644
index 000000000000..71d09420cb26
--- /dev/null
+++ b/toolchain/parser/testdata/generics/interface/self_pointer.carbon
@@ -0,0 +1,52 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// RUN: %{carbon-run-parser}
+// CHECK:STDOUT: [
+// CHECK:STDOUT:     {kind: 'InterfaceIntroducer', text: 'interface'},
+// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Foo'},
+// CHECK:STDOUT:   {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Sub'},
+// CHECK:STDOUT:       {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'SelfDeducedParameter', text: 'self'},
+// CHECK:STDOUT:             {kind: 'SelfType', text: 'Self'},
+// CHECK:STDOUT:           {kind: 'PostfixOperator', text: '*', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 4},
+// CHECK:STDOUT:       {kind: 'Address', text: 'addr', subtree_size: 5},
+// CHECK:STDOUT:     {kind: 'DeducedParameterList', text: ']', subtree_size: 7},
+// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
+// CHECK:STDOUT:         {kind: 'SelfType', text: 'Self'},
+// CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
+// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
+// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
+// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 17},
+// CHECK:STDOUT:     {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:     {kind: 'DeclaredName', text: 'Sub'},
+// CHECK:STDOUT:       {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'SelfDeducedParameter', text: 'self'},
+// CHECK:STDOUT:             {kind: 'NameReference', text: 'foo'},
+// CHECK:STDOUT:           {kind: 'PostfixOperator', text: '*', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 4},
+// CHECK:STDOUT:       {kind: 'Address', text: 'addr', subtree_size: 5},
+// CHECK:STDOUT:     {kind: 'DeducedParameterList', text: ']', subtree_size: 7},
+// CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
+// CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
+// CHECK:STDOUT:         {kind: 'SelfType', text: 'Self'},
+// CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
+// CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
+// CHECK:STDOUT:       {kind: 'SelfType', text: 'Self'},
+// CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
+// CHECK:STDOUT:   {kind: 'FunctionDeclaration', text: ';', subtree_size: 17},
+// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 38},
+// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT: ]
+
+interface Foo {
+  fn Sub[addr self: Self*](b: Self) -> Self;
+  fn Sub[addr self: foo*](b: Self) -> Self;
+}