Add parsing and handling of #pragma GCC diagnostic [GH #182]

src/Changes

@@ -1,5 +1,24 @@
 Version 7.1
 
+10/8/26  [GH #182]
+ "GCC diagnostic" pragmas
+
+The "GCC diagnostic" pragmas were not recognized, so in GNU modes each one
+was given an "unrecognized GCC pragma" warning.  For example, with --g++:
+
+  #pragma GCC diagnostic push   // Previously warned about.
+  #pragma GCC diagnostic ignored "-Wunused-parameter"
+  int f(int unused) { return 0; }
+  #pragma GCC diagnostic pop
+
+This is now fixed. The "error", "warning", and "ignored" forms, the "push"
+and "pop" forms (when emulating GCC 4.6 or later), the "ignored_attributes"
+form (when emulating GCC 13 or later), and the "fatal" form (when emulating
+clang) are accepted without a warning, to match the behavior of those
+compilers.  A missing option string is still diagnosed.  The pragmas have no
+effect on the front end's own diagnostics.
+
+
 10/7/26  [GH #176]
 C-generating back end: always_inline attribute and inlined setjmp calls
 

src/il_def.h

@@ -6619,6 +6619,7 @@ enum a_gcc_pragma_kind : a_byte {
   gcc_pk_push_options,          /* #pragma GCC push_options */
   gcc_pk_pop_options,           /* #pragma GCC pop_options */
   gcc_pk_reset_options,         /* #pragma GCC reset_options */
+  gcc_pk_diagnostic,            /* #pragma GCC diagnostic ... */
   gcc_pk_last
 };
 

src/preproc.c

@@ -4258,6 +4258,57 @@ kind indicates which of the above is being processed.
 }  /* process_gnu_options_pragma */
 
 
+static a_boolean process_gnu_diagnostic_pragma(a_pending_pragma_ptr  ppp)
+/*
+Handle
+   #pragma GCC diagnostic push
+   #pragma GCC diagnostic pop
+   #pragma GCC diagnostic kind "option"
+
+kind is recognized for: "error", "warning", "ignored", "fatal" (clang only),
+or "ignored_attributes" (for GCC 13 and later).
+
+"option" after kind is: an unchecked plain char string literal of type
+
+These pragmas control the warnings issued by the GCC or clang in the backend.
+Here, they are only accepted, and do not affect the diagnostics issued by the
+front end.  To match the behavior of GCC, any text following the pragma is
+ignored.  Return FALSE if the pragma is not a form recognized by the compiler
+being emulated.
+*/
+{
+  a_boolean  recognized = FALSE;
+
+  /* Skip the "diagnostic" identifier. */
+  (void)get_token();
+  if (curr_token == tok_identifier) {
+    a_const_char *str = locator_for_curr_id.symbol_header->identifier;
+    if (gnu_version >= 40600 &&
+        (strcmp(str, "push") == 0 || strcmp(str, "pop") == 0)) {
+      recognized = TRUE;
+    } else if (strcmp(str, "error") == 0 ||
+               strcmp(str, "warning") == 0 ||
+               strcmp(str, "ignored") == 0 ||
+               (clang_mode && strcmp(str, "fatal") == 0) ||
+               (gnu_version >= 130000 &&
+                strcmp(str, "ignored_attributes") == 0)) {
+      recognized = TRUE;
+      (void)get_token();
+      if (curr_token != tok_string_literal ||
+          !is_normal_character_kind(const_for_curr_token.character_kind)) {
+        /* The option (or attribute list) is missing.  Only a string literal
+           of plain char type is accepted. */
+        pos_warning(ec_exp_string_literal, &error_position);
+      }  /* if */
+    }  /* if */
+  }  /* if */
+  if (recognized) {
+    ppp->variant.gcc.kind = (a_gcc_pragma_kind)gcc_pk_diagnostic;
+  }  /* if */
+  return recognized;
+}  /* process_gnu_diagnostic_pragma */
+
+
 void gcc_pragma(a_pending_pragma_ptr  ppp)
 /*
 Process a "#pragma GCC ..." construct.
@@ -4289,6 +4340,9 @@ Process a "#pragma GCC ..." construct.
       process_gnu_options_pragma(ppp, (a_gcc_pragma_kind)gcc_pk_pop_options);
     } else if (gnu_version >= 40400 && strcmp(str, "reset_options") == 0) {
       process_gnu_options_pragma(ppp, (a_gcc_pragma_kind)gcc_pk_reset_options);
+    } else if (strcmp(str, "diagnostic") == 0) {
+      ignore_in_back_end = FALSE;
+      recognized = process_gnu_diagnostic_pragma(ppp);
 #if GNU_VECTOR_TYPES_ALLOWED && BUILTIN_FUNCTIONS_ENABLED
     } else if (target_is_arm_based() && target_is_64_bits() &&
                strcmp(str, "aarch64") == 0) {

tests/tests/changes/.EDGcpfe16990.rto/default.1.1.txt

@@ -1,9 +1 @@
 fe_only -DTEST_NUMBER=1 --g++ Test_name.c
-"Test_name.c", line 13: warning: unrecognized GCC pragma
-      _Pragma ("GCC diagnostic push")
-               ^
-
-"Test_name.c", line 14: warning: unrecognized GCC pragma
-      _Pragma ("GCC diagnostic pop")
-               ^
-

tests/tests/imported/clang/c/Preprocessor/.pragma_diagnostic_output.rto/default.1.1.txt

@@ -23,27 +23,3 @@ fe_only -DTEST_NUMBER=1 --clang -e 200 --no_wrap_diagnostics --clang_version 999
   #pragma clang diagnostic pop
           ^
 
-"Test_name.c", line 5: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic warning "-Wall"
-              ^
-
-"Test_name.c", line 7: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wall"
-              ^
-
-"Test_name.c", line 9: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic error "-Wall"
-              ^
-
-"Test_name.c", line 11: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic fatal "-Wall"
-              ^
-
-"Test_name.c", line 13: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push
-              ^
-
-"Test_name.c", line 15: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop
-              ^
-

tests/tests/imported/clang/c/Preprocessor/.pragma_diagnostic_output.rto/edg_x86_32_cp.1.1.txt

@@ -1,25 +1 @@
 fe_only -DTEST_NUMBER=1 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c Test_name.c
-"Test_name.c", line 5: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic warning "-Wall"
-              ^
-
-"Test_name.c", line 7: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wall"
-              ^
-
-"Test_name.c", line 9: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic error "-Wall"
-              ^
-
-"Test_name.c", line 11: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic fatal "-Wall"
-              ^
-
-"Test_name.c", line 13: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push
-              ^
-
-"Test_name.c", line 15: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop
-              ^
-

tests/tests/imported/clang/c/Preprocessor/.pragma_diagnostic_output.rto/edg_x86_64_cp.1.1.txt

@@ -1,25 +1 @@
 fe_only -DTEST_NUMBER=1 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c Test_name.c
-"Test_name.c", line 5: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic warning "-Wall"
-              ^
-
-"Test_name.c", line 7: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wall"
-              ^
-
-"Test_name.c", line 9: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic error "-Wall"
-              ^
-
-"Test_name.c", line 11: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic fatal "-Wall"
-              ^
-
-"Test_name.c", line 13: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push
-              ^
-
-"Test_name.c", line 15: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/default.2.1.txt

@@ -3,8 +3,4 @@ fe_only -DTEST_NUMBER=2 --clang -e 200 --no_wrap_diagnostics --clang_version 999
       int_val = __INT_MAX__, // INT_MAX
                 ^
 
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-
 1 error detected in the compilation of "Test_name.c".

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/default.4.1.txt

@@ -3,8 +3,4 @@ fe_only -DTEST_NUMBER=4 --clang -e 200 --no_wrap_diagnostics --clang_version 999
       int_val = __INT_MAX__, // INT_MAX
                 ^
 
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-
 1 error detected in the compilation of "Test_name.c".

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/default.5.1.txt

@@ -3,8 +3,4 @@ fe_only -DTEST_NUMBER=5 --clang -e 200 --no_wrap_diagnostics --clang_version 999
       int_val = __INT_MAX__, // INT_MAX
                 ^
 
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-
 1 error detected in the compilation of "Test_name.c".

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/default.6.1.txt

@@ -3,8 +3,4 @@ fe_only -DTEST_NUMBER=6 --clang -e 200 --no_wrap_diagnostics --clang_version 999
       int_val = __INT_MAX__, // INT_MAX
                 ^
 
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-
 1 error detected in the compilation of "Test_name.c".

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/default.7.1.txt

@@ -3,8 +3,4 @@ fe_only -DTEST_NUMBER=7 --clang -e 200 --no_wrap_diagnostics --clang_version 999
       int_val = __INT_MAX__, // INT_MAX
                 ^
 
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-
 1 error detected in the compilation of "Test_name.c".

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32.2.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=2 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32.4.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=4 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32.5.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=5 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32.6.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=6 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32.7.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=7 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32_cp.2.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=2 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32_cp.4.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=4 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32_cp.5.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=5 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32_cp.6.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=6 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.format-strings-signedness.rto/edg_x86_32_cp.7.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=7 --clang -e 200 --no_wrap_diagnostics --clang_version 999999 --c11 Test_name.c
-"Test_name.c", line 222: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wformat"
-              ^
-

tests/tests/imported/clang/c/Sema/.warn-deprecated-non-prototype.rto/default.1.1.txt

@@ -3,30 +3,6 @@ fe_only -DTEST_NUMBER=1 --clang -e 200 --no_wrap_diagnostics --clang_version 999
   void blapp() { } // both-error {{conflicting types for 'blapp'}} \
        ^
 
-"Test_name.c", line 68: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push
-              ^
-
-"Test_name.c", line 69: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wdeprecated-non-prototype"
-              ^
-
-"Test_name.c", line 71: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop
-              ^
-
-"Test_name.c", line 75: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push
-              ^
-
-"Test_name.c", line 76: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wstrict-prototypes"
-              ^
-
-"Test_name.c", line 78: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop
-              ^
-
 "Test_name.c", line 97: warning: variable "f" is used before its value is set
     f(); // OK
     ^

tests/tests/imported/gnu/c/.Wattribute-alias.rto/default.1.1.txt

@@ -1,16 +1,4 @@
 fe_only -DTEST_NUMBER=1 --gnu_version=999999 -e 200 --no_wrap --no_wrap_diagnostics --gcc Test_name.c
-"Test_name.c", line 19: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push "-Wattribute-alias"
-              ^
-
-"Test_name.c", line 20: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wattribute-alias"
-              ^
-
-"Test_name.c", line 23: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop "-Wattribute-alias"
-              ^
-
 "Test_name.c", line 54: warning: unknown attribute "leaf"
   ATTR (pure, leaf) F* resolve_to_const (void)
   ^

tests/tests/imported/gnu/c/.Wattribute-alias.rto/edg_x86_32_cp.1.1.txt

@@ -1,13 +1 @@
 fe_only -DTEST_NUMBER=1 --gnu_version=999999 -e 200 --no_wrap --no_wrap_diagnostics --gcc Test_name.c
-"Test_name.c", line 19: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push "-Wattribute-alias"
-              ^
-
-"Test_name.c", line 20: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wattribute-alias"
-              ^
-
-"Test_name.c", line 23: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop "-Wattribute-alias"
-              ^
-

tests/tests/imported/gnu/c/.Wattribute-alias.rto/edg_x86_64_cp.1.1.txt

@@ -1,13 +1 @@
 fe_only -DTEST_NUMBER=1 --gnu_version=999999 -e 200 --no_wrap --no_wrap_diagnostics --gcc Test_name.c
-"Test_name.c", line 19: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic push "-Wattribute-alias"
-              ^
-
-"Test_name.c", line 20: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wattribute-alias"
-              ^
-
-"Test_name.c", line 23: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic pop "-Wattribute-alias"
-              ^
-

tests/tests/imported/gnu/c/.Wbuiltin-declaration-mismatch-8.rto/default.1.1.txt

@@ -1,5 +1 @@
 fe_only -DTEST_NUMBER=1 --gnu_version=999999 -e 200 --no_wrap --no_wrap_diagnostics --gcc Test_name.c
-"Test_name.c", line 26: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic warning "-Wextra"
-              ^
-

tests/tests/imported/gnu/c/.Wbuiltin-declaration-mismatch-ignore.rto/default.1.1.txt

@@ -1,8 +1,4 @@
 fe_only -DTEST_NUMBER=1 --gnu_version=999999 -e 200 --no_wrap --no_wrap_diagnostics --gcc Test_name.c
-"Test_name.c", line 7: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic ignored "-Wbuiltin-declaration-mismatch"
-              ^
-
 "Test_name.c", line 11: warning: function "sscanf" declared implicitly
     sscanf (str, "%d", &i);
     ^

tests/tests/imported/gnu/c/.Werror-1.rto/default.1.1.txt

@@ -1,8 +1,4 @@
 fe_only -DTEST_NUMBER=1 --gnu_version=999999 -e 200 --no_wrap --no_wrap_diagnostics --gcc Test_name.c
-"Test_name.c", line 12: warning: unrecognized GCC pragma
-  #pragma GCC diagnostic error "-Waddress"
-              ^
-
 "Test_name.c", line 15: warning: unknown attribute "dj"
   void __attribute__((dj)) bar() { }	/* { dg-error ".* attribute directive ignored" } */
                       ^