Fix diagnostics for never-defined inline and nested functions (PR c/88720, PR c/88726).

Bugs 88720 and 88726 report issues where a function is declared inline
in an inner scope, resulting in spurious diagnostics about it being
declared but never defined when that scope is left (possibly in some
cases also wrongly referring to the function as a nested function).
These are regressions that were introduced with the support for C99
inline semantics in 4.3 (they don't appear with 4.2; it's possible
some aspects of the bugs might have been introduced later than 4.3).

For the case of functions being wrongly referred to as nested,
DECL_EXTERNAL was not the right condition for a function being
non-nested; TREE_PUBLIC is appropriate for the case of non-nested
functions with external linkage, while !b->nested means this is the
outermost scope in which the function was declared and so avoids
catching the case of a file-scope static being redeclared inline
inside a function.

For the non-nested, external-linkage case, the code attempts to avoid
duplicate diagnostics by diagnosing only when scope != external_scope,
but actually scope == external_scope is more appropriate, as it's only
when the file and external scopes are popped that the code can
actually tell whether a function ended up being defined, and all such
functions will appear in the (GCC-internal) external scope.

Bootstrapped with no regressions on x86_64-pc-linux-gnu.

	PR c/88720
	PR c/88726
gcc/c:
	* c-decl.c (pop_scope): Use TREE_PUBLIC and b->nested to determine
	whether a function is nested, not DECL_EXTERNAL.  Diagnose inline
	functions declared but never defined only for external scope, not
	for other scopes.

gcc/testsuite:
	* gcc.dg/inline-40.c, gcc.dg/inline-41.c: New tests.

From-SVN: r267665

5 files changed, 116 insertions, 2 deletions

diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index fbd94f5..5ee4b66 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,12 @@
+2019-01-07  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/88720
+	PR c/88726
+	* c-decl.c (pop_scope): Use TREE_PUBLIC and b->nested to determine
+	whether a function is nested, not DECL_EXTERNAL.  Diagnose inline
+	functions declared but never defined only for external scope, not
+	for other scopes.
+
 2019-01-07  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/85052
diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index d7726fa..5c7232f 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -1251,8 +1251,9 @@ pop_scope (void)
 	      && DECL_ABSTRACT_ORIGIN (p) != NULL_TREE
 	      && DECL_ABSTRACT_ORIGIN (p) != p)
 	    TREE_ADDRESSABLE (DECL_ABSTRACT_ORIGIN (p)) = 1;
-	  if (!DECL_EXTERNAL (p)
+	  if (!TREE_PUBLIC (p)
 	      && !DECL_INITIAL (p)
+	      && !b->nested
 	      && scope != file_scope
 	      && scope != external_scope)
 	    {
@@ -1268,7 +1269,7 @@ pop_scope (void)
 		 in the same translation unit."  */
 	      if (!flag_gnu89_inline
 		  && !lookup_attribute ("gnu_inline", DECL_ATTRIBUTES (p))
-		  && scope != external_scope)
+		  && scope == external_scope)
 		pedwarn (input_location, 0,
 			 "inline function %q+D declared but never defined", p);
 	      DECL_EXTERNAL (p) = 1;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 29b3b83..ebc96a3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-07  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/88720
+	PR c/88726
+	* gcc.dg/inline-40.c, gcc.dg/inline-41.c: New tests.
+
 2019-01-07  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* g++.dg/diagnostic/constexpr1.C: New.
diff --git a/gcc/testsuite/gcc.dg/inline-40.c b/gcc/testsuite/gcc.dg/inline-40.c
new file mode 100644
index 0000000..d0fdaee
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/inline-40.c
@@ -0,0 +1,49 @@
+/* Test inline functions declared in inner scopes.  Bugs 88720 and 88726.  */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+void
+inline_1 (void)
+{
+}
+
+void
+inline_2 (void)
+{
+}
+
+static void
+inline_static_1 (void)
+{
+}
+
+static void
+inline_static_2 (void)
+{
+}
+
+static void inline_static_3 (void);
+static void inline_static_4 (void);
+
+static void
+test (void)
+{
+  inline void inline_1 (void);
+  extern inline void inline_2 (void);
+  inline void inline_3 (void);
+  extern inline void inline_4 (void);
+  inline void inline_static_1 (void);
+  extern inline void inline_static_2 (void);
+  inline void inline_static_3 (void);
+  extern inline void inline_static_4 (void);
+}
+
+void
+inline_3 (void)
+{
+}
+
+void
+inline_4 (void)
+{
+}
diff --git a/gcc/testsuite/gcc.dg/inline-41.c b/gcc/testsuite/gcc.dg/inline-41.c
new file mode 100644
index 0000000..1511aee
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/inline-41.c
@@ -0,0 +1,49 @@
+/* Test inline functions declared in inner scopes.  Bugs 88720 and 88726.  */
+/* { dg-do compile } */
+/* { dg-options "-fgnu89-inline" } */
+
+void
+inline_1 (void)
+{
+}
+
+void
+inline_2 (void)
+{
+}
+
+static void
+inline_static_1 (void)
+{
+}
+
+static void
+inline_static_2 (void)
+{
+}
+
+static void inline_static_3 (void);
+static void inline_static_4 (void);
+
+static void
+test (void)
+{
+  inline void inline_1 (void);
+  extern inline void inline_2 (void);
+  inline void inline_3 (void);
+  extern inline void inline_4 (void);
+  inline void inline_static_1 (void);
+  extern inline void inline_static_2 (void);
+  inline void inline_static_3 (void);
+  extern inline void inline_static_4 (void);
+}
+
+void
+inline_3 (void)
+{
+}
+
+void
+inline_4 (void)
+{
+}