Fix documentation tests

Author: rcvalle

src/doc/rustc/src/exploit-mitigations.md

@@ -150,7 +150,7 @@ randomization (ASLR). This is also referred to as “full ASLR”.
 The Rust compiler supports position-independent executable and enables it by
 default since version 0.12.0 (2014-10-09)[10]–[13].
 
-```
+```text
 $ readelf -h target/release/hello-rust | grep Type:
   Type:                              DYN (Shared object file)
 ```
@@ -171,15 +171,15 @@ resulting in an overflow or wraparound.
 The Rust compiler supports integer overflow checks, and enables it when
 debug assertions are enabled since version 1.1.0 (2015-06-25)[14]–[20].
 
-```rust
+```compile_fail
 fn main() {
     let u: u8 = 255;
     println!("u: {}", u + 1);
 }
 ```
 Fig. 2. hello-rust-integer program.
 
-```
+```text
 $ cargo run
    Compiling hello-rust-integer v0.1.0 (/home/rcvalle/hello-rust-integer)
     Finished dev [unoptimized + debuginfo] target(s) in 0.23s
@@ -189,7 +189,7 @@ note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
 ```
 Fig. 3. Build and execution of hello-rust-integer with debug assertions enabled.
 
-```
+```text
 $ cargo run --release
    Compiling hello-rust-integer v0.1.0 (/home/rcvalle/hello-rust-integer)
     Finished release [optimized] target(s) in 0.23s
@@ -232,7 +232,7 @@ default since its initial release, version 0.1 (2012-01-20)[21], [22], but
 has regressed since then[23]–[25], and enforced by default since version
 1.8.0 (2016-04-14)[25].
 
-```
+```text
 $ readelf -l target/release/hello-rust | grep -A 1 GNU_STACK
   GNU_STACK      0x0000000000000000 0x0000000000000000 0x0000000000000000
                  0x0000000000000000 0x0000000000000000  RW     0x10
@@ -299,7 +299,7 @@ also referred to as “partial RELRO”.
 The Rust compiler supports read-only relocations, and enables it by default
 since version 1.21.0 (2017-10-12)[30], [31].
 
-```
+```text
 $ readelf -l target/release/hello-rust | grep GNU_RELRO
   GNU_RELRO      0x000000000002ee00 0x000000000002fe00 0x000000000002fe00
 ```
@@ -321,7 +321,7 @@ RELRO”.
 The Rust compiler supports immediate binding, and enables it by default
 since version 1.21.0 (2017-10-12)[30], [31].
 
-```
+```text
 $ readelf -d target/release/hello-rust | grep BIND_NOW
  0x000000000000001e (FLAGS)              BIND_NOW
 ```
@@ -366,7 +366,7 @@ C library default allocator<sup id="fnref:5" role="doc-noteref"><a
 href="#fn:5" class="footnote">5</a></sup> since version 1.32.0
 (2019-01-17)[39].
 
-```rust
+```should_panic
 fn main() {
     let mut x = Box::new([0; 1024]);
 
@@ -380,7 +380,7 @@ fn main() {
 ```
 Fig. 11. hello-rust-heap program.
 
-```
+```text
 $ cargo run
    Compiling hello-rust-heap v0.1.0 (/home/rcvalle/hello-rust-heap)
     Finished dev [unoptimized + debuginfo] target(s) in 0.25s
@@ -390,7 +390,7 @@ Aborted
 ```
 Fig. 12. Build and execution of hello-rust-heap with debug assertions enabled.
 
-```
+```text
 $ cargo run --release
    Compiling hello-rust-heap v0.1.0 (/home/rcvalle/hello-rust-heap)
     Finished release [optimized] target(s) in 0.25s
@@ -456,7 +456,7 @@ class="footnote">6</a></sup>. There is work currently ongoing to add support
 for the [sanitizers](https://github.com/google/sanitizers)[40], which may or
 may not include support for LLVM CFI.
 
-```
+```text
 $ readelf -s target/release/hello-rust | grep __cfi_init
 ```
 Fig. 15. Checking if LLVM CFI is enabled for a given binary.
@@ -502,7 +502,7 @@ currently ongoing to add support for the sanitizers[40], which may or may
 not include support for safe stack<sup id="fnref:7" role="doc-noteref"><a
 href="#fn:7" class="footnote">7</a></sup>.
 
-```
+```text
 $ readelf -s target/release/hello-rust | grep __safestack_init
 ```
 Fig. 16. Checking if LLVM SafeStack is enabled for a given binary.