[05/27] Don't allow NULL as an argument to block_static_block

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 40f85914a56..dfcd9a5fcd1 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -13815,7 +13815,11 @@  class ada_language : public language_defn
   {
     struct block_symbol sym;
 
-    sym = ada_lookup_symbol (name, block_static_block (block), domain);
+    sym = ada_lookup_symbol (name,
+			     (block == nullptr
+			      ? nullptr
+			      : block_static_block (block)),
+			     domain);
     if (sym.symbol != NULL)
       return sym;
 
diff --git a/gdb/block.c b/gdb/block.c
index 97a0214e037..d21729f069d 100644
--- a/gdb/block.c
+++ b/gdb/block.c
@@ -364,12 +364,12 @@  block_set_using (struct block *block,
 }
 
 /* Return the static block associated to BLOCK.  Return NULL if block
-   is NULL or if block is a global block.  */
+   is a global block.  */
 
 const struct block *
 block_static_block (const struct block *block)
 {
-  if (block == NULL || block->superblock () == NULL)
+  if (block->superblock () == NULL)
     return NULL;
 
   while (block->superblock ()->superblock () != NULL)
diff --git a/gdb/compile/compile-c-symbols.c b/gdb/compile/compile-c-symbols.c
index 00ac4523f86..79490b811c3 100644
--- a/gdb/compile/compile-c-symbols.c
+++ b/gdb/compile/compile-c-symbols.c
@@ -212,7 +212,6 @@  static void
 convert_symbol_sym (compile_c_instance *context, const char *identifier,
 		    struct block_symbol sym, domain_enum domain)
 {
-  const struct block *static_block;
   int is_local_symbol;
 
   /* If we found a symbol and it is not in the  static or global
@@ -227,7 +226,9 @@  convert_symbol_sym (compile_c_instance *context, const char *identifier,
      }
   */
 
-  static_block = block_static_block (sym.block);
+  const struct block *static_block = nullptr;
+  if (sym.block != nullptr)
+    static_block = block_static_block (sym.block);
   /* STATIC_BLOCK is NULL if FOUND_BLOCK is the global block.  */
   is_local_symbol = (sym.block != static_block && static_block != NULL);
   if (is_local_symbol)
@@ -613,6 +614,9 @@  generate_c_for_variable_locations (compile_instance *compiler,
 				   const struct block *block,
 				   CORE_ADDR pc)
 {
+  if (block == nullptr)
+    return {};
+
   const struct block *static_block = block_static_block (block);
 
   /* If we're already in the static or global block, there is nothing
diff --git a/gdb/compile/compile-cplus-symbols.c b/gdb/compile/compile-cplus-symbols.c
index 2df68b7dd32..45a76eef303 100644
--- a/gdb/compile/compile-cplus-symbols.c
+++ b/gdb/compile/compile-cplus-symbols.c
@@ -239,7 +239,9 @@  convert_symbol_sym (compile_cplus_instance *instance,
      }
   */
 
-  const struct block *static_block = block_static_block (sym.block);
+  const struct block *static_block = nullptr;
+  if (sym.block != nullptr)
+    static_block = block_static_block (sym.block);
   /* STATIC_BLOCK is NULL if FOUND_BLOCK is the global block.  */
   bool is_local_symbol = (sym.block != static_block && static_block != nullptr);
   if (is_local_symbol)
diff --git a/gdb/cp-support.c b/gdb/cp-support.c
index b7ed2101b78..08f7c2b4140 100644
--- a/gdb/cp-support.c
+++ b/gdb/cp-support.c
@@ -1306,7 +1306,8 @@  add_symbol_overload_list_namespace (const char *func_name,
     }
 
   /* Look in the static block.  */
-  block = block_static_block (get_selected_block (0));
+  block = get_selected_block (0);
+  block = block == nullptr ? nullptr : block_static_block (block);
   if (block)
     add_symbol_overload_list_block (name, block, overload_list);
 
@@ -1456,6 +1457,9 @@  add_symbol_overload_list_qualified (const char *func_name,
     add_symbol_overload_list_block (func_name, b, overload_list);
 
   surrounding_static_block = block_static_block (get_selected_block (0));
+  surrounding_static_block = (surrounding_static_block == nullptr
+			      ? nullptr
+			      : block_static_block (surrounding_static_block));
 
   /* Go through the symtabs and check the externs and statics for
      symbols which match.  */
diff --git a/gdb/symtab.c b/gdb/symtab.c
index b3445133c8c..0e522b2c7f9 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -2179,13 +2179,15 @@  lookup_local_symbol (const char *name,
 		     const domain_enum domain,
 		     enum language language)
 {
+  if (block == nullptr)
+    return {};
+
   struct symbol *sym;
   const struct block *static_block = block_static_block (block);
   const char *scope = block_scope (block);
   
-  /* Check if either no block is specified or it's a global block.  */
-
-  if (static_block == NULL)
+  /* Check if it's a global block.  */
+  if (static_block == nullptr)
     return {};
 
   while (block != static_block)
@@ -2484,6 +2486,9 @@  lookup_symbol_in_static_block (const char *name,
 			       const struct block *block,
 			       const domain_enum domain)
 {
+  if (block == nullptr)
+    return {};
+
   const struct block *static_block = block_static_block (block);
   struct symbol *sym;
 
@@ -5855,7 +5860,7 @@  default_collect_symbol_completion_matches_break_on
      visible from current context.  */
 
   b = get_selected_block (0);
-  surrounding_static_block = block_static_block (b);
+  surrounding_static_block = b == nullptr ? nullptr : block_static_block (b);
   surrounding_global_block = block_global_block (b);
   if (surrounding_static_block != NULL)
     while (b != surrounding_static_block)