Make the assertion level thread local

... by moving CurrentAssertionLevel to the kernel, into the GAPState.

While at it, also validate the level argument given to Assert(), and error out
if it is not a non-negative small integer.

While no code should have ever directly accessed CurrentAssertionLevel, there
is a minimal chance that some legacy code somewhere does this. To make sure it
suddenly runs with an incorrect assertion level without anybody noticing, we
keep defining CurrentAssertionLevel, but as a constant bound to `false`. This
way, any code trying to modify it, or to compare it against an integer, will
run into an error.

lib/read1.g

@@ -47,7 +47,6 @@ ReadLib( "record.gd"   );
 ReadLib( "random.gd"   );
 
 ReadLib( "cache.gi"    );
-ReadLib( "assert.gd"   );
 ReadLib( "coll.gi"     );
 
 ReadLib( "flag.g"      );
@@ -80,7 +79,6 @@ ReadLib( "mat8bit.gd"   );
 ReadLib( "global.gd"   );
 
 ReadLib( "info.gi"     );
-ReadLib( "assert.gi"   );
 ReadLib( "global.gi"   );
 
 ReadLib( "options.gd"  );

src/compiler.c

@@ -4971,7 +4971,7 @@ static void CompAssert2(Stat stat)
 
     Emit( "\n/* Assert( ... ); */\n" );
     lev = CompExpr(READ_STAT(stat, 0));
-    Emit( "if ( ! LT(CurrentAssertionLevel, %c) ) {\n", lev );
+    Emit( "if ( STATE(CurrentAssertionLevel) >= %i ) {\n", lev );
     cnd = CompBoolExpr(READ_STAT(stat, 1));
     Emit( "if ( ! %c ) {\n", cnd );
     Emit( "AssertionFailure();\n" );
@@ -4996,7 +4996,7 @@ static void CompAssert3(Stat stat)
 
     Emit( "\n/* Assert( ... ); */\n" );
     lev = CompExpr(READ_STAT(stat, 0));
-    Emit( "if ( ! LT(CurrentAssertionLevel, %c) ) {\n", lev );
+    Emit( "if ( STATE(CurrentAssertionLevel) >= %i ) {\n", lev );
     cnd = CompBoolExpr(READ_STAT(stat, 1));
     Emit( "if ( ! %c ) {\n", cnd );
     msg = CompExpr(READ_STAT(stat, 2));

src/gap.c

@@ -1377,6 +1377,20 @@ static Obj FuncUPDATE_STAT(Obj self, Obj name, Obj newStat)
 }
 
 
+static Obj FuncSetAssertionLevel(Obj self, Obj level)
+{
+    RequireNonnegativeSmallInt("SetAssertionLevel", level);
+    STATE(CurrentAssertionLevel) = INT_INTOBJ(level);
+    return 0;
+}
+
+
+static Obj FuncAssertionLevel(Obj self)
+{
+    return INTOBJ_INT(STATE(CurrentAssertionLevel));
+}
+
+
 /****************************************************************************
 **
 *V  GVarFuncs . . . . . . . . . . . . . . . . . . list of functions to export
@@ -1423,6 +1437,10 @@ static StructGVarFunc GVarFuncs[] = {
     GVAR_FUNC_1ARGS(MASTER_POINTER_NUMBER, ob),
     GVAR_FUNC_1ARGS(BREAKPOINT, integer),
     GVAR_FUNC_2ARGS(UPDATE_STAT, string, object),
+
+    GVAR_FUNC_1ARGS(SetAssertionLevel, level),
+    GVAR_FUNC_0ARGS(AssertionLevel),
+
     { 0, 0, 0, 0, 0 }
 
 };
@@ -1474,7 +1492,7 @@ static Int PostRestore (
     MemoryAllocated   = GVarName( "memory_allocated"  );
 
     QUITTINGGVar      = GVarName( "QUITTING" );
-    
+
     return 0;
 }
 
@@ -1505,6 +1523,10 @@ static Int InitLibrary (
     AssReadOnlyGVar(GVarName("time"), INTOBJ_INT(0));
     AssReadOnlyGVar(GVarName("memory_allocated"), INTOBJ_INT(0));
 
+    // ensure any legacy code which directly tries to set the former GAP
+    // global 'CurrentAssertionLevel' or tries to compare to an integer,
+    // runs into an error.
+    AssConstantGVar(GVarName("CurrentAssertionLevel"), False);
 
     return PostRestore( module );
 }

src/gapstate.h

@@ -42,6 +42,9 @@ typedef struct GAPState {
     Obj  StackObj;
     Obj  Tilde;
 
+    // The current assertion level for use in Assert
+    Int CurrentAssertionLevel;
+
     /* From gvar.c */
     Obj CurrNamespace;
 

src/intrprtr.c

@@ -3808,16 +3808,12 @@ void            IntrInfoEnd( UInt narg )
 *F  IntrAssertEnd2Args() . . . . called after reading the closing parenthesis
 *F  IntrAssertEnd3Args() . . . . called after reading the closing parenthesis
 **
-*V  CurrentAssertionLevel  . .  . . . . . . . . . . . .  copy of GAP variable
-**
 **
 **  STATE(IntrIgnoring) is increased by (a total of) 2 if an assertion either
 **  is not tested (because we were Ignoring when we got to it, or due to
 **  level) or is tested and passes
 */
 
-Obj              CurrentAssertionLevel;
-
 void              IntrAssertBegin ( void )
 {
     /* ignore or code                                                      */
@@ -3830,18 +3826,16 @@ void              IntrAssertBegin ( void )
 
 void             IntrAssertAfterLevel ( void )
 {
-  Obj level;
-
     /* ignore or code                                                      */
     SKIP_IF_RETURNING();
     if ( STATE(IntrIgnoring)  > 0 ) { STATE(IntrIgnoring)++; return; }
     if ( STATE(IntrCoding)    > 0 ) { CodeAssertAfterLevel(); return; }
 
 
-    level = PopObj();
+    Int level = GetSmallIntEx("Assert", PopObj(), "<lev>");
 
-    if (LT( CurrentAssertionLevel, level))
-           STATE(IntrIgnoring) = 1;
+    if (STATE(CurrentAssertionLevel) < level)
+        STATE(IntrIgnoring) = 1;
 }
 
 void             IntrAssertAfterCondition ( void )
@@ -3934,7 +3928,6 @@ static Int InitKernel (
     InitGlobalBag( &STATE(Tilde), "STATE(Tilde)" );
 #endif
 
-    InitCopyGVar( "CurrentAssertionLevel", &CurrentAssertionLevel );
     InitFopyGVar( "CONVERT_FLOAT_LITERAL_EAGER", &CONVERT_FLOAT_LITERAL_EAGER);
 
     /* The work of handling Options is also delegated*/
@@ -3945,22 +3938,6 @@ static Int InitKernel (
 }
 
 
-/****************************************************************************
-**
-*F  InitLibrary( <module> ) . . . . . . .  initialise library data structures
-*/
-static Int InitLibrary (
-    StructInitInfo *    module )
-{
-    UInt            lev;
-
-    /* The Assertion level is also controlled at GAP level                 */
-    lev = GVarName("CurrentAssertionLevel");
-    AssGVar( lev, INTOBJ_INT(0) );
-
-    return 0;
-}
-
 static Int InitModuleState(void)
 {
     STATE(IntrCoding) = 0;
@@ -3981,7 +3958,6 @@ static StructInitInfo module = {
     .type = MODULE_BUILTIN,
     .name = "intrprtr",
     .initKernel = InitKernel,
-    .initLibrary = InitLibrary,
 
     .initModuleState = InitModuleState,
 };

src/intrprtr.h

@@ -859,8 +859,6 @@ void IntrInfoEnd(UInt narg);
 **
 *F  IntrAssertEnd2Args() . . . . called after reading the closing parenthesis
 *F  IntrAssertEnd3Args() . . . . called after reading the closing parenthesis
-**
-*V  CurrentAssertionLevel . . . .  . . . . . . . . . . . copy of GAP variable
 */
 
 void IntrAssertBegin(void);
@@ -869,8 +867,6 @@ void IntrAssertAfterCondition(void);
 void IntrAssertEnd2Args(void);
 void IntrAssertEnd3Args(void);
 
-extern Obj              CurrentAssertionLevel;
-
 /****************************************************************************
 **
 *F  IntrSaveWSBegin() . . . . . . . . . . . . . Start interpreting a save WS

src/stats.c

@@ -892,10 +892,13 @@ static UInt ExecInfo(Stat stat)
 static UInt ExecAssert2Args(Stat stat)
 {
     Obj             level;
+    Int             lev;
     Obj             cond;
 
     level = EVAL_EXPR(READ_STAT(stat, 0));
-    if ( ! LT(CurrentAssertionLevel, level) )  {
+    lev = GetSmallIntEx("Assert", level, "<lev>");
+
+    if (STATE(CurrentAssertionLevel) >= lev) {
         cond = EVAL_EXPR(READ_STAT(stat, 1));
         RequireTrueOrFalse("Assert", cond);
         if (cond == False) {
@@ -917,11 +920,14 @@ static UInt ExecAssert2Args(Stat stat)
 static UInt ExecAssert3Args(Stat stat)
 {
     Obj             level;
+    Int             lev;
     Obj             cond;
     Obj             message;
 
     level = EVAL_EXPR(READ_STAT(stat, 0));
-    if ( ! LT(CurrentAssertionLevel, level) ) {
+    lev = GetSmallIntEx("Assert", level, "<lev>");
+
+    if (STATE(CurrentAssertionLevel) >= lev) {
         cond = EVAL_EXPR(READ_STAT(stat, 1));
         RequireTrueOrFalse("Assert", cond);
         if (cond == False) {