checker,cgen: fix `-os cross` support for `$if !solaris { #include <sys/ptrace.h> }`

vlib/v/ast/ast.v

@@ -874,7 +874,7 @@ pub mut:
 	scope &Scope
 }
 
-// #include etc
+// #include, #define etc
 pub struct HashStmt {
 pub:
 	mod         string
@@ -885,6 +885,8 @@ pub mut:
 	kind     string // : 'include'
 	main     string // : '<openssl/rand.h>'
 	msg      string // : 'please install openssl'
+	ct_conds []Expr // *all* comptime conditions, that must be true, for the hash to be processed
+	// ct_conds is filled by the checker, based on the current nesting of `$if cond1 {}` blocks
 }
 
 /*

vlib/v/checker/checker.v

@@ -78,6 +78,7 @@ pub mut:
 	inside_ct_attr bool // true inside [if expr]
 	skip_flags     bool // should `#flag` and `#include` be skipped
 	fn_level       int  // 0 for the top level, 1 for `fn abc() {}`, 2 for a nested fn, etc
+	ct_cond_stack  []ast.Expr
 mut:
 	files                            []ast.File
 	expr_level                       int  // to avoid infinite recursion segfaults due to compiler bugs
@@ -4908,6 +4909,9 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 	if c.skip_flags {
 		return
 	}
+	if c.ct_cond_stack.len > 0 {
+		node.ct_conds = c.ct_cond_stack.clone()
+	}
 	if c.pref.backend.is_js() {
 		if !c.file.path.ends_with('.js.v') {
 			c.error('hash statements are only allowed in backend specific files such "x.js.v"',
@@ -6551,6 +6555,7 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
 				// statements, in `-os cross` mode
 				found_branch = false
 				c.skip_flags = false
+				c.ct_cond_stack << branch.cond
 			}
 			if !c.skip_flags {
 				c.stmts(branch.stmts)
@@ -6573,6 +6578,9 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
 				c.comptime_fields_type.delete(comptime_field_name)
 			}
 			c.skip_flags = cur_skip_flags
+			if c.fn_level == 0 && c.pref.output_cross_c && c.ct_cond_stack.len > 0 {
+				c.ct_cond_stack.pop()
+			}
 		} else {
 			// smartcast sumtypes and interfaces when using `is`
 			c.smartcast_if_conds(branch.cond, mut branch.scope)

vlib/v/gen/c/cgen.v

@@ -1358,6 +1358,19 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 			g.writeln('goto $node.name;')
 		}
 		ast.HashStmt {
+			mut ct_condition := ''
+			if node.ct_conds.len > 0 {
+				ct_condition_start := g.out.len
+				for idx, ct_expr in node.ct_conds {
+					g.comp_if_cond(ct_expr, false)
+					if idx < node.ct_conds.len - 1 {
+						g.write(' && ')
+					}
+				}
+				ct_condition = g.out.cut_to(ct_condition_start).trim_space()
+				// dump(node)
+				// dump(ct_condition)
+			}
 			// #include etc
 			if node.kind == 'include' {
 				mut missing_message := 'Header file $node.main, needed for module `$node.mod` was not found.'
@@ -1372,17 +1385,39 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 					guarded_include = '#include $node.main'
 				}
 				if node.main.contains('.m') {
+					g.definitions.writeln('\n')
+					if ct_condition.len > 0 {
+						g.definitions.writeln('#if $ct_condition')
+					}
 					// Objective C code import, include it after V types, so that e.g. `string` is
 					// available there
-					g.definitions.writeln('// added by module `$node.mod`:')
+					g.definitions.writeln('// added by module `$node.mod`')
 					g.definitions.writeln(guarded_include)
+					if ct_condition.len > 0 {
+						g.definitions.writeln('#endif // \$if $ct_condition')
+					}
+					g.definitions.writeln('\n')
 				} else {
-					g.includes.writeln('// added by module `$node.mod`:')
+					g.includes.writeln('\n')
+					if ct_condition.len > 0 {
+						g.includes.writeln('#if $ct_condition')
+					}
+					g.includes.writeln('// added by module `$node.mod`')
 					g.includes.writeln(guarded_include)
+					if ct_condition.len > 0 {
+						g.includes.writeln('#endif // \$if $ct_condition')
+					}
+					g.includes.writeln('\n')
 				}
 			} else if node.kind == 'define' {
-				g.includes.writeln('// defined by module `$node.mod` in file `$node.source_file`:')
+				if ct_condition.len > 0 {
+					g.includes.writeln('#if $ct_condition')
+				}
+				g.includes.writeln('// defined by module `$node.mod`')
 				g.includes.writeln('#define $node.main')
+				if ct_condition.len > 0 {
+					g.includes.writeln('#endif // \$if $ct_condition')
+				}
 			}
 		}
 		ast.Import {}

vlib/v/tests/project_with_c_code_ct_ifs/a_linux.h

@@ -0,0 +1 @@
+char *version = "linux";

vlib/v/tests/project_with_c_code_ct_ifs/a_nonlinux.h

@@ -0,0 +1 @@
+char *version = "non-linux";

vlib/v/tests/project_with_c_code_ct_ifs/ctimeifblock.v

@@ -0,0 +1,11 @@
+$if linux {
+	#include "@VMODROOT/a_linux.h"
+}
+
+$if !linux {
+	#include "@VMODROOT/a_nonlinux.h"
+}
+
+fn main() {
+	C.printf(c'a: %s\n', C.version)
+}