From a42e39a7b974645d2820931357e99411fdb0beb6 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 24 Nov 2022 11:00:54 +0100
Subject: [PATCH] c: Propagate erroneous types to declaration specifiers
 [PR107805]

Without this change, finish_declspecs cannot tell that whether there
was an erroneous type specified, or no type at all.  This may result
in additional diagnostics for implicit ints, or missing diagnostics
for multiple types.

	PR c/107805

gcc/c/
	* c-decl.cc (declspecs_add_type): Propagate error_mark_bode
	from type to specs.

gcc/testsuite/
	* gcc.dg/pr107805-1.c: New test.
	* gcc.dg/pr107805-2.c: Likewise.
---
 gcc/c/c-decl.cc                   | 6 ++----
 gcc/testsuite/gcc.dg/pr107805-1.c | 5 +++++
 gcc/testsuite/gcc.dg/pr107805-2.c | 4 ++++
 3 files changed, 11 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr107805-1.c
 create mode 100644 gcc/testsuite/gcc.dg/pr107805-2.c

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 098e475f65d5..4adb89e4aaf1 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -12243,11 +12243,9 @@ declspecs_add_type (location_t loc, struct c_declspecs *specs,
     error_at (loc, "two or more data types in declaration specifiers");
   else if (TREE_CODE (type) == TYPE_DECL)
     {
-      if (TREE_TYPE (type) == error_mark_node)
-	; /* Allow the type to default to int to avoid cascading errors.  */
-      else
+      specs->type = TREE_TYPE (type);
+      if (TREE_TYPE (type) != error_mark_node)
 	{
-	  specs->type = TREE_TYPE (type);
 	  specs->decl_attr = DECL_ATTRIBUTES (type);
 	  specs->typedef_p = true;
 	  specs->explicit_signed_p = C_TYPEDEF_EXPLICITLY_SIGNED (type);
diff --git a/gcc/testsuite/gcc.dg/pr107805-1.c b/gcc/testsuite/gcc.dg/pr107805-1.c
new file mode 100644
index 000000000000..559b6a5586eb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr107805-1.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+typedef int t;
+typedef struct { double a; int b; } t; /* { dg-error "conflicting types" } */
+t x; /* No warning here.  */
+
diff --git a/gcc/testsuite/gcc.dg/pr107805-2.c b/gcc/testsuite/gcc.dg/pr107805-2.c
new file mode 100644
index 000000000000..fa5fa4ce2733
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr107805-2.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+typedef int t;
+typedef struct { double a; int b; } t; /* { dg-error "conflicting types" } */
+t char x; /* { dg-error "two or more data types" } */