From bb391cb24d8f92ecad10bb6a60abdf0b880de0dd Mon Sep 17 00:00:00 2001 From: Bruno Larsen Date: Wed, 26 Oct 2022 09:47:11 +0200 Subject: [PATCH] gdb/c++: Detect ambiguous variables in imported namespaces When running gdb.cp/nsusing.cc and stopping at line 17, we can ask GDB to print x and get a compiler-dependent answer. Using gcc 12.2.1, GDB will print M::x, and using clang 16.0.0 prints N::x. Not only is this behavior confusing to users, it is also not consistent with compiler behaviors, which would warn that using x is ambiguous at this point. This commit makes GDB behavior consistent with compilers. it achieves this by making it so instead of exiting early when finding any symbol with the correct name, GDB continues searching through all include directives, storing all matching symbols in a relational map betwen the mangled name and the found symbols. If the resulting map has more than one entry, GDB says that the reference is ambiguous and lists all possibilities. Otherwise it returns the block_symbol structure for the desired symbol, or an empty struct if nothing was found. The commit also changes gdb.cp/nsusing.exp to test the ambiguous detection. --- gdb/cp-namespace.c | 97 ++++++++++++++++++++++++-------- gdb/testsuite/gdb.cp/nsusing.exp | 13 ++++- 2 files changed, 83 insertions(+), 27 deletions(-) diff --git a/gdb/cp-namespace.c b/gdb/cp-namespace.c index 421d30bb7ee..b1c54c57da6 100644 --- a/gdb/cp-namespace.c +++ b/gdb/cp-namespace.c @@ -32,6 +32,7 @@ #include "buildsym.h" #include "language.h" #include "namespace.h" +#include #include static struct block_symbol @@ -344,7 +345,10 @@ cp_lookup_symbol_in_namespace (const char *the_namespace, const char *name, return sym; } -/* Search for NAME by applying all import statements belonging to +/* This version of the function is internal, use the wrapper unless + the list of ambiguous symbols is needed. + + Search for NAME by applying all import statements belonging to BLOCK which are applicable in SCOPE. If DECLARATION_ONLY the search is restricted to using declarations. Example: @@ -372,27 +376,35 @@ cp_lookup_symbol_in_namespace (const char *the_namespace, const char *name, SEARCH_SCOPE_FIRST is an internal implementation detail: Callers must pass 0 for it. Internally we pass 1 when recursing. */ -static struct block_symbol +static void cp_lookup_symbol_via_imports (const char *scope, const char *name, const struct block *block, const domain_enum domain, const int search_scope_first, const int declaration_only, - const int search_parents) + const int search_parents, + std::map& found_symbols) { struct using_direct *current; struct block_symbol sym = {}; int len; int directive_match; + /* All the symbols we found will be kept in this relational map between + the mangled name and the block_symbol found. We do this so that GDB + won't incorrectly report an ambiguous symbol for finding the same + thing twice. */ + /* First, try to find the symbol in the given namespace if requested. */ if (search_scope_first) - sym = cp_lookup_symbol_in_namespace (scope, name, - block, domain, 1); - - if (sym.symbol != NULL) - return sym; + { + sym = cp_lookup_symbol_in_namespace (scope, name, + block, domain, 1); + if (sym.symbol != nullptr) + found_symbols[sym.symbol->m_name] = sym; + } /* Due to a GCC bug, we need to know the boundaries of the current block to know if a certain using directive is valid. */ @@ -446,7 +458,7 @@ cp_lookup_symbol_via_imports (const char *scope, if (declaration_only || sym.symbol != NULL || current->declaration) { if (sym.symbol != NULL) - return sym; + found_symbols[sym.symbol->m_name] = sym; continue; } @@ -467,23 +479,57 @@ cp_lookup_symbol_via_imports (const char *scope, sym = cp_lookup_symbol_in_namespace (scope, current->import_src, block, domain, 1); + found_symbols[sym.symbol->m_name] = sym; } else if (current->alias == NULL) { /* If this import statement creates no alias, pass current->inner as NAMESPACE to direct the search towards the imported namespace. */ - sym = cp_lookup_symbol_via_imports (current->import_src, - name, block, - domain, 1, 0, 0); + cp_lookup_symbol_via_imports (current->import_src, name, + block, domain, 1, 0, 0, + found_symbols); } - if (sym.symbol != NULL) - return sym; } } +} - return {}; +/* Wrapper for the actual cp_lookup_symbol_via_imports. This wrapper sets + search_scope_first correctly and handles errors if needed. */ +static struct block_symbol +cp_lookup_symbol_via_imports (const char *scope, + const char *name, + const struct block *block, + const domain_enum domain, + const int declaration_only, + const int search_parents) +{ + std::map found_symbols; + + cp_lookup_symbol_via_imports(scope, name, block, domain, 0, + declaration_only, search_parents, + found_symbols); + + if (found_symbols.size () > 1) + { + auto itr = found_symbols.cbegin (); + std::string error_str = "Reference to \""; + error_str += name; + error_str += "\" is ambiguous, possibilities are: "; + error_str += itr->second.symbol->print_name (); + for (itr++; itr != found_symbols.end (); itr++) + { + error_str += " and "; + error_str += itr->second.symbol->print_name (); + } + error (_("%s"), error_str.c_str ()); + } + + if (found_symbols.size() == 1) + return found_symbols.cbegin ()->second; + else + return {}; } /* Helper function that searches an array of symbols for one named NAME. */ @@ -503,9 +549,10 @@ search_symbol_list (const char *name, int num, return NULL; } -/* Like cp_lookup_symbol_via_imports, but if BLOCK is a function, it - searches through the template parameters of the function and the - function's type. */ +/* Search for symbols whose name match NAME in the given SCOPE. + if BLOCK is a function, we'll search first through the template + parameters and function type. Afterwards (or if BLOCK is not a function) + search through imported directives using cp_lookup_symbol_via_imports. */ struct block_symbol cp_lookup_symbol_imports_or_template (const char *scope, @@ -514,7 +561,6 @@ cp_lookup_symbol_imports_or_template (const char *scope, const domain_enum domain) { struct symbol *function = block->function (); - struct block_symbol result; symbol_lookup_debug_printf ("cp_lookup_symbol_imports_or_template (%s, %s, %s, %s)", @@ -583,10 +629,11 @@ cp_lookup_symbol_imports_or_template (const char *scope, } } - result = cp_lookup_symbol_via_imports (scope, name, block, domain, 0, 1, 1); - symbol_lookup_debug_printf - ("cp_lookup_symbol_imports_or_template (...) = %s", - result.symbol != NULL ? host_address_to_string (result.symbol) : "NULL"); + struct block_symbol result + = cp_lookup_symbol_via_imports (scope, name, block, domain, 1, 1); + symbol_lookup_debug_printf ("cp_lookup_symbol_imports_or_template (...) = %s\n", + result.symbol != nullptr + ? host_address_to_string (result.symbol) : "NULL"); return result; } @@ -603,8 +650,8 @@ cp_lookup_symbol_via_all_imports (const char *scope, const char *name, while (block != NULL) { - sym = cp_lookup_symbol_via_imports (scope, name, block, domain, 0, 0, 1); - if (sym.symbol) + sym = cp_lookup_symbol_via_imports (scope, name, block, domain, 0, 1); + if (sym.symbol != nullptr) return sym; block = block->superblock (); diff --git a/gdb/testsuite/gdb.cp/nsusing.exp b/gdb/testsuite/gdb.cp/nsusing.exp index f118dfc2d30..f34910bac0d 100644 --- a/gdb/testsuite/gdb.cp/nsusing.exp +++ b/gdb/testsuite/gdb.cp/nsusing.exp @@ -126,11 +126,20 @@ gdb_test_multiple "print x" "print x, before using statement" { -re -wrap "No symbol .x. in current context.*" { pass $gdb_test_name } - -re -wrap "= 911.*" { + -re -wrap "Reference to .x. is ambiguous.*" { # GCC doesn't properly set the decl_line for namespaces, so GDB believes # that the "using namespace M" line has already passed at this point. xfail $gdb_test_name } } gdb_test "next" ".*" "using namespace M" -gdb_test "print x" "= 911" "print x, only using M" +gdb_test_multiple "print x" "print x, only using M" { + -re -wrap "= 911.*" { + pass $gdb_test_name + } + -re -wrap "Reference to .x. is ambiguous.*" { + xfail $gdb_test_name + } +} +gdb_test "next" ".*" "using namespace N" +gdb_test "print x" "Reference to .x. is ambiguous.*" "print x, with M and N" -- 2.30.2